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Datasheet XE88LC05/05A Sensing
Machine Data Acquisition MCU
with Zooming ADC and DACs

XE88LC05/05A

Sensing Machine

Data Acquisition with 16+10 bit ZoomingADCTM
and buffered 16 and 8 bit DACs

General Description

The XE88LC05A is a data acquisition ultra low-
power low-voltage system on a chip (SoC) with a
high efficiency microcontroller unit embedded
(MCU), allowing for 1 MIPS at 300uA and 2.4 V,
and multiplying in one clock cycle.

The XE88LC05A includes a high resolution
acquisition path with the 16+10 bits ZoomingADC
and two buffered DACs.

The XE88LC05A is available with on chip ROM or
Multiple-Time-Programmable (MTP) program
memory.

Applications

Portable, battery operated instruments

Current loop powered instruments

Wheatstone bridge interfaces

Pressure and chemical sensors

HVAC

control

Metering

Sports watches, wrist instruments

Key product Features

Low-power, high resolution ZoomingADC

0.5 to 1000 gain with offset cancellation

up to 16 bits analog to digital converter

up to 13 inputs multiplexer

Low-voltage

low-power

controller operation

2 MIPS with 2.4 V to 5.5 V operation

300 µA at 1 MIPS over voltage range

22 kByte (8 kInstruction) MTP

520 Byte RAM data memory

RC and crystal oscillators

5 reset, 22 interrupt, 8 event sources

8 bit and 16 bit buffered DACs

100 years MTP Flash retention at 55°C

Ordering Information

Product Temperature

range

Memory

type

Package

XE88LC05MI028*

-40°C to 85 °C

MTP

LQFP64

XE88LC05AMI000

-40°C to 85 °C

MTP

die

XE88LC05AMI028

-40°C to 85 °C

MTP

LQFP64

XE88LC05ARE000

-40°C to 125 °C

ROM

die

XE88LC05ARE028

-40°C to 125 °C

ROM

LQFP64

*Not for new designs

1-2

D0304-40

Datasheet
XE88LC05/05A

1.1 Top schematic

1.1.1 General description

The top level block schematic of the circuit is shown in Figure 1-1. The heart of the circuit consists of
the Coolrisc816® CPU core. This core includes an 8x8 multiplier and 16 internal registers.

The bus controller generates all control signals for access to all data registers other than the CPU
internal registers.

The reset block generates the adequate reset signals for the rest of the circuit as a function of the set-
up contained in its control registers. Possible reset sources are the power-on-reset (POR), the
external pin RESET, the watchdog (WD), a bus error detected by the bus controller or a
programmable pattern on Port A. Different low power modes are implemented.

The clock generation and power management block sets up the clock signals and generates internal
supplies for different blocks. The clock can be generated from the RC oscillator (this is the start-up
condition), the crystal oscillator (XTAL) or an external clock source (given on the OSCIN pin).

The test controller generates all set-up signals for different test modes. In normal operation, it is used
as a set of 8 low power data registers. If power consumption is important for the application, the
variables that need to be accessed very often should be stored in these registers rather than in the
RAM.

The IRQ handler routes the interrupt signals of the different peripherals to the IRQ inputs of the CPU
core. It allows masking of the interrupt sources and it flags which interrupt source is active.

Events are generally used to restart the processor after a HALT period without jumping to a specified
address, i.e. the program execution resumes with the instruction following the HALT instruction. The
EVN handler routes the event signals of the different peripherals to the EVN inputs of the CPU core. It
allows masking of the interrupt sources and it flags which interrupt source is active.

The Port B is an 8 bit parallel IO port with analog capabilities. The URST, UART, and PWM block also
make use of this port.

The instruction memory is a 22-bit wide flash or ROM memory depending on the circuit version. Flash
and ROM versions have both 8k instruction memory. The data memory of this product is 512 byte
SRAM.

The Acquisition Chain is a high resolution acquisition path with the 16+10 bit fully differential
ZoomingADC

. The VMULT (voltage multiplier) powers a part of the Acquisition Chain.

The signal D/A (DAS) is a 16 bit D/A based on sigma-delta modulation. It includes a stand-alone
amplifier that can be used for analog output filtering.

The bias D/A (DAB) is an 8 bit low frequency D/A. It includes a stand-alone amplifier that is used to
drive large currents. It can be used to bias a sensor.

The Port A is an 8 bit parallel input port. It can also generate interrupts, events or a reset. It can be
used to input external clocks for the timer/counter/PWM block.

The Port C is a general purpose 8 bit parallel I/O port.

The USRT (universal synchronous receiver/transmitter) contains some simple hardware functions in
order to simplify the software implementation of a synchronous serial link.

1-4

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Datasheet
XE88LC05/05A

The counters/timers/PWM can take their clocks from internal or external sources (on Port A) and can
generate interrupts or events. The PWM is output on Port B.

The VLD (voltage level detector) detects the battery end of life with respect to a programmable
threshold.

1.1.2 XE88LC05 vs XE88LC05A

The XE88LC05A has a new RESET pin function. The action of the RESET pin of the XE88LC05A
resets the clock registers too and creates an additional short delay. See the RESET chapter for more
information.

1.2 Pin map

1.2.1 Bare die

(52.6,4123.5) PA(0)

(52.6, 3908.5) PA(1)

(52.6,3693.5) PA(2)

(52.6, 3478.5) PA(3)

(52.6, 3263.5) VBAT

(52.6, 3048.5) PA(4)

(52.6, 2833.5) PA(5)

(52.6, 2618.5) PA(6)

(52.6, 2403.5) PA(7)

(52.6, 2188.5) PC(0)

(52.6, 1973.5) PC(1)

(52.6, 1758.5) PC(2)

(52.6, 1543.5) PC(3)

(52.6, 1328.5) VSS

(52.6, 1113.5) PC(4)

(52.6, 898.5) PC(5)

(52.6, 683.5) PC(6)

(52.6, 468.5) PC(7)

AC_R(0) (3958.4, 4118.5)

AC_R(1) (3958.4, 3858.5)

VSS (3958.4, 3603.5)

AC_A(0) (3958.4, 3343.5)

AC_A(1) (3958.4, 3088.5)

AC_A(2) (3958.4, 2828.5)

AC_A(3) (3958.4, 2573.5)

AC_A(4) (3958.4, 2313.5)

VBAT (3958.4, 2058.5)

AC_A(5) (3958.4,1798.5)

AC_A(6) (3958.4, 1543.5)

AC_A(7) (3958.4, 1283.5)

AC_R(2) (3958.4, 1028.5)

AC_R(3) (3958.4, 768.5)

VPP/TEST (3958.4, 508.5)

(

4
28.

453

)

I
N

(

593

.
5
, 4

453

.
4
)

(

7
58.

4
453

)

OUT ( 923

.
5
, 4

453

.
4
)

SET

(

108

8
.
5,

53.4

)

(

125

2
.
9,

53.4

)

(14

1
8
.5,

445

3.4

)

S
S

_
R

(15

88.

4
453

)

7
53.

453

)

(19

2
3
.5,

445

3.4

)

DAS_AO (3

114

.6, 445

3
.
4)

DAS_AI

_
M

293

.5, 445

3
.
4)

DAS_

AI_P

4
58.

5, 4

453.

4
)

DAS_OUT (3

6
28.5

,
4

4
5
3
.
4
)

(

3
9
8
.
5
,

4
7
.
6
)

(
0
)

(

5
3
3
.
5
,

4
7
.
6
)

(
1
)

(

6
6
8
.
5
,

4
7
.
6
)

(
2
)

(

7
9
8
.
5
,

4
7
.
6
)

(
3
)

(

9
3
3
.
5
,

4
7
.
6
)

(
4
)

(
1
0
63.

47.

8
.
5
,

4
7
.
6
)

(
5
)

8
.
5
,

4
7
.
6
)

(
6
)

3
.
5
,

4
7
.
6
)

(
7
)

(
1
5
9
3
.
5,

47.

B_R_

(17

2
8
.
5
,
47

.6)

DAB

_
R

_
M

(
1
8
58.

47.

B_O

(
2
0
42.

.
6
)

_
P

(
268

3.3,

4
7
.
6
)
D

_
M

(
3
363

.5,

4
7
.
6
)

VSS

(34

9
8
.5,

47.

DAB

_AI_P

(362

8.4,

47.

6
)
D

I_M

4100

460

Figure 1-2. Die dimensions and pin coordinates (in µm)

1-6

D0304-40

Datasheet
XE88LC05/05A

Package pin

name

Package pin

name

21 PB(4) 53

DAS_AI_M

22 PB(5) 54

DAS_AO

23 PB(6) 55 VBAT
24 PB(7) 56 VSS
25 DAB_R_P 57 VSS_REG
26 DAB_R_M 58 VREG
27 DAB_OUT 59

28 DAB_AO_P 60 VMULT
29 DAB_AO_M 61 RESET
30 DAB_AI_P 62 OSCOUT
31 DAB_AI_M 63 OSCIN
32 NC 64 NC

Table 1-1. Bonding plan of the LQFP-64 package (LQFP 64L 10x10mm thick 1.6 mm)

1.3 Pin assignment

The table below gives a short description of the different pin assignments.

Pin

Assignment

VBAT

Positive power supply

VSS VSS_REG

Negative power supply

VREG

Connection for the mandatory external capacitor of the voltage regulator

VPP/TEST

High voltage supply for flash memory programming (NC in ROM versions)

RESET

Resets the circuit when the voltage is high

OSCIN/OSCOUT

Quartz crystal connections, also used for flash memory programming

PA(7:0)

Parallel input port A pins

PB(7:0)

Parallel I/O port B pins

PC(7:0)

Parallel I/O port C pins

AC_A(7:0)

Acquisition chain input pins

AC_R(3:0)

Acquisition chain reference pins

VMULT

Connection for the external capacitor if VBAT is below 3V

DAB_OUT

Bias D/A output

DAB_R_x

Bias D/A reference (x=P: plus, x=M: minus)

DAB_Ax_y

Bias D/A amplifier IO (x=I: input, x=O: output ; y=P: plus, y=M: minus)

DAS_OUT

Signal D/A output

DAS_AI_x

Signal D/A amplifier inputs (x=P: plus, x=M: minus)

DAS_AO

Signal D/A amplifier output

Table 1-2. Pin assignment

Table 1-3 gives a more detailed pin map for the different pins. It also indicates the possible I/O
configuration of these pins. The indications in blue bold are the configuration at start-up.

The pins CNTx pins are possible counter inputs, PWMx are possible PWM outputs.

1-7

D0304-40

Datasheet
XE88LC05/05A

pin function

I/O configuration

lqfp-64

first

second

third

POWER

PA(0)

CNTA

PA(1)

CNTB

PA(2)

CNTC

PA(3)

CNTD

PA(4)

PA(5)

PA(6)

PA(7)

PC(0)

PC(1)

PC(2)

PC(3)

PC(4)

PC(5)

PC(6)

PC(7)

PB(0)

PWM0 X

X X X

PB(1)

PWM1 X

X X X

PB(2)

X X X

PB(3)

X X X

PB(4)

USRT_S0

X X X

PB(5)

USRT_S1

X X X

PB(6)

UART_Tx

X X X

PB(7)

UART_Rx

X X X

DAB_R_P

DAB_R_M

DAB_OUT

DAB_AO_P

DAB_AO_M

DAB_AI_P

DAB_AI_M

VPP

TEST

AC_R(3)

AC_R(2)

AC_A(7)

AC_A(6)

AC_A(5)

AC_A(4)

AC_A(3)

AC_A(2)

AC_A(1)

AC_A(0)

AC_R(1)

AC_R(0)

DAS_OUT

DAS_AI_P

DAS_AI_M

DAS_AO

VBAT

2-2

D0304-40

Datasheet
XE88LC05/05A

2.1 Absolute maximum ratings

Table 2-1. Absolute maximum ratings

Min.

Max.

Note

Voltage applied to VBAT with respect to VSS

-0.3

6.0

Voltage applied to VPP with respect to VSS

VBAT-0.3

Voltage applied to all pins except VPP and VBAT

VSS-0.3

VBAT+0.3

Storage temperature (ROM device or unprogrammed
flash device)

-55 150

°C

Storage temperature (programmed flash device)

-40

°C

Stresses beyond the absolute maximal ratings may cause permanent damage to the device.
Functional operation at the absolute maximal ratings is not implied. Exposure to conditions beyond
the absolute maximal ratings may affect the reliability of the device.

2.2 Operating

range

Table 2-2. Operating range for the flash device

Min.

Max.

Note

Voltage applied to VBAT with respect to VSS

2.4

5.5

Voltage applied to VBAT with respect to VSS during
the flash programming

3.3 5.5

Voltage applied to VPP with respect to VSS

VBAT

11.5

Voltage applied to all pins except VPP and VBAT

VSS

VBAT

Operating temperature range

-40

°C

Capacitor on VREG (flash version)

0.8

1.2

Capacitor on VMULT

1.0

3.0

1. During the programming of the device, the supply voltage should at least be equal to the

supply voltage used during normal operation.

2. The capacitor on VREG is mandatory.
3. The capacitor on VMULT is optional. The capacitor has to be present if the multiplier is

enabled. The multiplier has to be enabled if VBAT<3.0V.

Table 2-3. Operating range for the ROM device

Min.

Max.

Note

Voltage applied to VBAT with respect to VSS

2.4

5.5

Voltage applied to all pins except VPP and VBAT

VSS

VBAT

Operating temperature range

-40

125

°C

Capacitor on VREG

0.1

1.2

Capacitor on VMULT

1.0

3.0

1. The capacitor may be omitted when VREG is connected to VBAT.
2. The capacitor on VMULT is optional. The capacitor has to be present if the multiplier is

enabled. The multiplier has to be enabled if VBAT<3.0V.

All specifications in this document are valid for the complete operating range unless otherwise
specified.

2-3

D0304-40

Datasheet
XE88LC05/05A

Table 2-4. Operating range of the Flash memory

Min.

Max.

Note

Retention time at 85°C

years 1

Retention time at 55°C

100

years 1

Number of programming cycles

1. Valid only if programmed using a programming tool that is qualified
2. Circuits can be programmed more than 10 times but after that, the retention time is no

longer guaranteed. All qualification tests have been done after 10 cycles.

2.3 Supply

configurations

2.3.1 Flash

circuit

The flash version of the circuit can be run from a supply between 2.4V and 5.5V (Figure 2-1). The
capacitor on VREG has to be connected at all times (value in Table 2-2) to guarantee proper
operation of the device. The capacitor on VMULT is only required if the circuit is to be operated below
3V.

VBAT

VREG

VMULT

VSS

2.4V 5.5V

vreg

vmult

Figure 2-1. Supply configuration for the flash circuit.

2.3.2 ROM

circuit

For the ROM version, two possible operating modes exist: with and without voltage regulator. Using
the voltage regulator, low power consumption will be obtained even with supply voltages above 2.4V.
Without the voltage regulator (i.e. VREG short-circuited to VBAT), a higher speed can be obtained.

2.3.2.1

Low power operation

In this case, the internal voltage regulator is used in order to maintain low power consumption
independent from the supply voltage. The capacitor on VREG has to be connected at all times (value
in Table 2-3) to guarantee proper operation of the device. The capacitor on VMULT has to be
connected only when VBAT<3V.

2-5

D0304-40

Datasheet
XE88LC05/05A

0 2.15 2.4 3.3 VBAT (V)

CPU
parallel and serial ports
RC and crystal oscillator
VLD
Counters and PWM
DAS (without amplifier)

acquisition chain
voltage multiplier
DAB

Figure 2-4. Operation range of the different circuit blocks

2.4 Current

consumption

The tables below give the current consumption for the circuit in different configurations. The figures
are indicative only and may change as a function of the actual software implemented in the circuit.

Table 2-5 gives the current consumption for the flash version of the circuit. The peripherals are
disabled. The parallel ports A and B are configured in input with pull up, the parallel port C is
configured as an output. Their pins are not connected externally. The pin RESET is connected to VSS
and the pin VPP/TEST is connected to VBAT. The inputs of the acquisition chain are connected to
VSS.

Table 2-5. Typical current consumption of the XE88LC05 version (8k instructions flash memory)

Operation mode

CPU

Xtal

Consumption comments

Note

High speed CPU

1 MIPS

1 MHz

Off

310

A 2.4V<>5.5V,

Low power CPU

32 kIPS

Off

32 kHz

2.4V <>5.5V, 27

Low power time
keeping

HALT Off 32

kHz 1.0

2.4V <>5.5V, 27

Fast wake-up
time keeping

HALT Ready 32kHz

1.7

2.4V <>5.5V, 27

Immediate wake-
up time keeping

HALT 100

kHz Off

1.4

2.4V <>5.5V, 27

VLD static current

2.4V <>5.5V, 27

16 bit resolution
data acquisition

HALT 2

MHz Off

190

A 3.0V,

12 bit , gain 100,
data acquisition

HALT 2

MHz Off

460

A 3.0V,

1. PGA disabled, ADC enabled, 16 bit resolution
2. PGA 1 disabled, PGA 2 and 3 enabled, ADC enabled, 12 bit resolution

For more information concerning the current consumption of the zoomingADC

, see the chapter

power consumption in the acquisition chain documentation which shows the current consumption of
this block as a function of temperature and voltage and for different configurations of the PGA and
ADC.

The power consumption of the ROM version of the circuit is identical if it is configured as shown in
Figure 2-2. In the high speed configuration, the current consumption will increase proportional with
VBAT.

3-2

D0304-40

Datasheet
XE88LC05/05A

3.1 CPU

description

The CPU of the XE8000 series is a low power RISC core. It has 16 internal registers for efficient
implementation of the C compiler. Its instruction set is made up of 35 generic instructions, all coded
on 22 bits, with 8 addressing modes. All instructions are executed in one clock cycle, including
conditional jumps and 8x8 multiplication. The circuit therefore runs on 1 MIPS on a 1MHz clock.

The CPU hardware and software description is given in the document "Coolrisc816 Hardware and
Software Reference Manual". A short summary is given in the following paragraphs.

The good code efficiency of the CPU core makes it possible to compute a polynomial like

)

(

in less than 300 clock cycles (software code generated by the

XEMICS C-compiler, all numbers are signed integers on 16 bits).

3.2

CPU internal registers

As shown in Figure 3-1, the CPU has 16 internal 8-bit registers. Some of these registers can be
concatenated to a 16-bit word for use in some instructions. The function of these registers is defined
in Table 3-1. The status register stat (Table 3-2) is used to manage the different interrupt and event
levels. An interrupt or an event can both be used to wake up after a HALT instruction. The difference
is that an interrupt jumps to a special interrupt function whereas an event continues the software
execution with the instruction following the HALT instruction.

The program counter (PC) is a 16 bit register that indicates the address of the instruction that has to
be executed. The stack (ST

) is used to memorise the return address when executing subroutines or

interrupt routines.

Instruction

memory

22bit

CPU

U inter

n
al

e
g
i
ster

stat

iph

ipl

i3h

i3l

i2h

i2l

i1h

i1l

i0h

i0l

Data memory

t
a
b

u
s

inst

cti

o
n bu

program counter stack

Figure 3-1. CPU internal registers

3-3

D0304-40

Datasheet
XE88LC05/05A

r0 general

purpose

r1 general

purpose

r2 general

purpose

data memory offset

i0h

MSB of the data memory index i0

i0l

LBS of the data memory index i0

i1h

MSB of the data memory index i1

i1l

LBS of the data memory index i1

i2h

MSB of the data memory index i2

i2l

LBS of the data memory index i2

i3h

MSB of the data memory index i3

i3l

LBS of the data memory index i3

iph

MSB of the program memory index ip

ipl

LBS of the program memory index ip

stat status

a accumulator

Table 3-1. CPU internal register definition

bit

name function

IE2

enables (when 1) the interrupt request of level 2

IE1

enables (when 1) the interrupt request of level 1

GIE

enables (when 1) all interrupt request levels

IN2

interrupt request of level 2. The interrupts labelled "low" in the interrupt handler are
routed to this interrupt level. This bit has to be cleared when the interrupt is served.

IN1

interrupt request of level 1. The interrupts labelled "mid" in the interrupt handler are
routed to this interrupt level. This bit has to be cleared when the interrupt is served.

IN0

interrupt request of level 0. The interrupts labelled "hig" in the interrupt handler are
routed to this interrupt level. This bit has to be cleared when the interrupt is served.

EV1

event request of level 1. The events labelled "low" in the event handler are routed to
this event level. This bit has to be cleared when the event is served.

EV0

event request of level 1. The events labelled "hig" in the event handler are routed to
this event level. This bit has to be cleared when the event is served.

Table 3-2. Status register description

The CPU also has a number of flags that can be used for conditional jumps. These flags are defined
in Table 3-3.

symbol name

function

zero

Z=1 when the accumulator a content is zero

carry

This flag is used in shift or arithmetic operations.
For a shift operation, it has the value of the bit that was shifted out (LSB for shift
right, MSB for shift left).
For an arithmetic operation with unsigned numbers:

it is 1 at occurrence of an overflow during an addition (or equivalent).

it is 0 at occurrence of an underflow during a subtraction (or equivalent).

overflow This flag is used in shift or arithmetic operations.

For arithmetic or shift operations with signed numbers, it is 1 if an overflow or
underflow occurs.

Table 3-3. Flag description

3-4

D0304-40

Datasheet
XE88LC05/05A

3.3

CPU instruction short reference

Table 3-4 shows a short description of the different instructions available on the Coolrisc816. The
notation

in the conditional jump instruction refers to the condition description as given in Table 3-6.

The notation

reg, reg1, reg2, reg3

refers to one of the CPU internal registers of Table 3-1. The

notation

eaddr

and

DM(eaddr)

refer to one of the extended address modes as defined in Table 3-5.

The notation DM(xxx) refers to the data memory location with address xxx.

Instruction

Modification Operation

Jump addr[15:0]

-,-,-, -

PC := addr[15:0]

Jump ip

-,-,-, -

PC := ip

addr[15:0]

-,-,-, -

is true then PC := addr[15:0]

-,-,-, -

is true then PC := ip

Call addr[15:0]

-,-,-, -

n+1

:= ST

(n>1); ST

:= PC+1; PC := addr[15:0]

Call ip

-,-,-, -

n+1

:= ST

(n>1); ST

:= PC+1; PC := ip

Calls addr[15:0]

-,-,-, -

ip := PC+1; PC := addr[15:0]

Calls ip

-,-,-, -

ip := PC+1; PC := ip

Ret

-,-,-, -

PC := ST

; ST

:= ST

n+1

(n>1)

Rets

-,-,-, -

PC := ip

Reti

-,-,-, -

PC := ST

; ST

:= ST

n+1

(n>1); GIE :=1

Push

-,-,-, -

PC := PC+1; ST

n+1

:= ST

(n>1); ST

:= ip

Pop

-,-,-, -

PC := PC+1; ip := ST

; ST

:= ST

n+1

(n>1)

Move

reg

,#data[7:0]

-,-, Z, a

a := data[7:0];

reg

:= data[7:0]

Move

reg1

reg2

-,-, Z, a

a :=

reg2

;

reg1

reg2

Move

reg

eaddr

-,-, Z, a

a :=

DM(eaddr)

;

reg

DM(eaddr)

Move

eaddr

reg

-,-,-, -

DM(eaddr)

reg

Move addr[7:0],#data[7:0]

-,-,-, -

DM(addr[7:0]) := data[7:0]

Cmvd

reg1

reg2

-,-, Z, a

a :=

reg2

; if C=0 then

reg1

:= a;

Cmvd

reg

eaddr

-,-, Z, a

a :=

DM(eaddr)

;

if C=0 then

reg

:= a

Cmvs

reg1

reg2

-,-, Z, a

a :=

reg2

; if C=1 then

reg1

:= a;

Cmvs

reg

eaddr

-,-, Z, a

a :=

DM(eaddr)

;

if C=1 then

reg

:= a

Shl

reg1

reg2

C, V, Z, a

a :=

reg2

<<1;

a[0] := 0; C :=

reg2[7]

;

reg1

:= a

Shl

reg

C, V, Z, a

a :=

reg

<<1; a[0] := 0; C :=

reg[7]

;

reg

:= a

Shl

reg

eaddr

C, V, Z, a

a :=

DM(eaddr)

<<1; a[0] :=0; C :=

DM(eaddr)[7]

;

reg

:= a

Shlc

reg1

reg2

C, V, Z, a

a :=

reg2

<<1;

a[0] := C; C :=

reg2[7]

;

reg1

:= a

Shlc

reg

C, V, Z, a

a :=

reg

<<1; a[0] := C; C :=

reg[7]

;

reg

:= a

Shlc

reg

eaddr

C, V, Z, a

a :=

DM(eaddr)

<<1; a[0] := C; C :=

DM(eaddr)[7]

;

reg

:= a

Shr

reg1

reg2

C, V, Z, a

a :=

reg2

>>1;

a[7] := 0; C :=

reg2[0]

;

reg1

:=a

Shr

reg

C, V, Z, a

a :=

reg

>>1; a[7] := 0; C :=

reg[0]

;

reg

:= a

Shr

reg

eaddr

C, V, Z, a

a :=

DM(eaddr)

>>1; a[7] := 0; C :=

DM(eaddr)[0]

;

reg

:= a

Shrc

reg1

reg2

C, V, Z, a

a :=

reg2

>>1;

a[7] := C; C :=

reg2[0]

;

reg1

:= a

Shrc

reg

C, V, Z, a

a :=

reg

>>1; a[7] := C; C :=

reg[0]

;

reg

:= a

Shrc

reg

eaddr

C, V, Z, a

a :=

DM(eaddr)

>>1; a[7] := C; C :=

DM(eaddr)[0]

;

reg

:= a

Shra

reg1

reg2

C, V, Z, a

a :=

reg2

>>1;

a[7] :=

reg2[7]

; C :=

reg2[0]

;

reg1

:= a

Shra

reg

C, V, Z, a

a :=

reg

>>1; a[7] :=

reg[7]

; C :=

reg[0]

;

reg

:= a

Shra

reg

eaddr

C, V, Z, a

a :=

DM(eaddr)

>>1; a[7] :=

DM(eaddr)[7]

; C :=

DM(eaddr)[0]

;

reg

:= a

Cpl1

reg1

reg2

-,-, Z, a

a := NOT(

reg2

);

reg1

:= a

Cpl1

reg

-,-, Z, a

a := NOT(

reg

);

reg

:= a

Cpl1

reg

eaddr

-,-, Z, a

a := NOT(

DM(eaddr)

);

reg

:= a

Cpl2

reg1

reg2

C, V, Z, a

a := NOT(

reg2

)+1; if a=0 then C:=1 else C := 0;

reg1

:= a

Cpl2

reg

C, V, Z, a

a := NOT(

reg

)+1; if a=0 then C:=1 else C := 0;

reg

:= a

Cpl2

reg

eaddr

C, V, Z, a

a := NOT(

DM(eaddr)

)+1; if a=0 then C:=1 else C := 0;

reg

:= a

Cpl2c

reg1

reg2

C, V, Z, a

a := NOT(

reg2

)+C; if a=0 and C=1 then C:=1 else C := 0;

reg1

:= a

Cpl2c

reg

C, V, Z, a

a := NOT(

reg

)+C; if a=0 and C=1 then C:=1 else C := 0;

reg

:= a

Cpl2c

reg

eaddr

C, V, Z, a

a := NOT(

DM(eaddr)

)+C; if a=0 and C=1 then C:=1 else C := 0;

reg

:= a

Inc

reg1

reg2

C, V, Z, a

a :=

reg2

+1; if a=0 then C := 1 else C := 0;

reg1

:= a

Inc

reg

C, V, Z, a

a :=

reg

+1; if a=0 then C := 1 else C := 0;

reg

:= a

Inc

reg

eaddr

C, V, Z, a

a :=

DM(eaadr)

+1; if a=0 then C := 1 else C := 0;

reg

:= a

Incc

reg1

reg2

C, V, Z, a

a :=

reg2

+C; if a=0 and C=1 then C := 1 else C := 0;

reg1

:= a

Incc

reg

C, V, Z, a

a :=

reg

+C; if a=0 and C=1 then C := 1 else C := 0;

reg

:= a

Incc

reg

eaddr

C, V, Z, a

a :=

DM(eaadr)

+C; if a=0 and C=1 then C := 1 else C := 0;

reg

:= a

Dec

reg1

reg2

C, V, Z, a

a :=

reg2

-1; if a=hFF then C := 0 else C := 1;

reg1

:= a

3-5

D0304-40

Datasheet
XE88LC05/05A

Dec

reg

C, V, Z, a

a :=

reg

-1; if a=hFF then C := 0 else C := 1;

reg

:= a

Dec

reg

eaddr

C, V, Z, a

a :=

DM(eaddr)

-1; if a=hFF then C := 0 else C := 1;

reg

:= a

Decc

reg1

reg2

C, V, Z, a

a :=

reg2

-(1-C); if a=hFF and C=0 then C := 0 else C := 1;

reg1

:= a

Decc

reg

C, V, Z, a

a :=

reg

-(1-C); if a=hFF and C=0 then C := 0 else C := 1;

reg

:= a

Decc

reg

eaddr

C, V, Z, a

a :=

DM(eaddr)

-(1-C); if a=hFF and C=0 then C := 0 else C := 1;

reg

:= a

And

reg

,#data[7:0]

-,-, Z, a

a :=

reg

and data[7:0];

reg

:= a

And

reg1

reg2

reg3

-,-, Z, a

a :=

reg2

and

reg3

;

reg1

:= a

And

reg1

reg2

-,-, Z, a

a :=

reg1

and

reg2

;

reg1

:= a

And

reg

eaddr

-,-, Z, a

a :=

reg

and

DM(eaddr)

;

reg

:= a

reg

,#data[7:0]

-,-, Z, a

a :=

reg

or data[7:0];

reg

:= a

reg1

reg2

reg3

-,-, Z, a

a :=

reg2

reg3

;

reg1

:= a

reg1

reg2

-,-, Z, a

a :=

reg1

reg2

;

reg1

:= a

reg

eaddr

-,-, Z, a

a :=

reg

DM(eaddr)

;

reg

:= a

Xor

reg

,#data[7:0]

-,-, Z, a

a :=

reg

xor data[7:0];

reg

:= a

Xor

reg1

reg2

reg3

-,-, Z, a

a :=

reg2

xor

reg3

;

reg1

:= a

Xor

reg1

reg2

-,-, Z, a

a :=

reg1

xor

reg2

;

reg1

:= a

Xor

reg

eaddr

-,-, Z, a

a :=

reg

DM(eaddr)

;

reg

:= a

Add

reg

,#data[7:0]

C, V, Z, a

a :=

reg

+data[7:0]; if overflow then C:=1 else C := 0;

reg

:= a

Add

reg1

reg2

reg3

C, V, Z, a

a :=

reg2

reg3

; if overflow then C:=1 else C := 0;

reg1

:= a

Add

reg1

reg2

C, V, Z, a

a :=

reg1

reg2

; if overflow then C:=1 else C := 0;

reg1

:= a

Add

reg

eaddr

C, V, Z, a

a :=

reg

DM(eaddr)

; if overflow then C:=1 else C := 0;

reg

:= a

Addc

reg

,#data[7:0]

C, V, Z, a

a :=

reg

+data[7:0]+C; if overflow then C:=1 else C := 0;

reg

:= a

Addc

reg1

reg2

reg3

C, V, Z, a

a :=

reg2

reg3

+C; if overflow then C:=1 else C := 0;

reg1

:= a

Addc

reg1

reg2

C, V, Z, a

a :=

reg1

reg2

+C; if overflow then C:=1 else C := 0;

reg1

:= a

Addc

reg

eaddr

C, V, Z, a

a :=

reg

DM(eaddr)

+C; if overflow then C:=1 else C := 0;

reg

:= a

Subd

reg

,#data[7:0]

C, V, Z, a

a := data[7:0]-

reg

; if underflow then C := 0 else C := 1;

reg

:= a

Subd

reg1

reg2

reg3

C, V, Z, a

a :=

reg2

reg3

; if underflow then C := 0 else C := 1;

reg1

:= a

Subd

reg1

reg2

C, V, Z, a

a :=

reg2

reg1

; if underflow then C := 0 else C := 1;

reg1

:= a

Subd

reg

eaddr

C, V, Z, a

a :=

DM(eaddr)

reg

; if underflow then C := 0 else C := 1;

reg

:= a

Subdc

reg

,#data[7:0]

C, V, Z, a

a := data[7:0]-

reg

-(1-C); if underflow then C := 0 else C := 1;

reg

:= a

Subdc

reg1

reg2

reg3

C, V, Z, a

a :=

reg2

reg3

-(1-C); if underflow then C := 0 else C := 1;

reg1

:= a

Subdc

reg1

reg2

C, V, Z, a

a :=

reg2

reg1

-(1-C); if underflow then C := 0 else C := 1;

reg1

:= a

Subdc

reg

eaddr

C, V, Z, a

a :=

DM(eaddr)

reg

-(1-C); if underflow then C := 0 else C := 1;

reg

:= a

Subs

reg

,#data[7:0]

C, V, Z, a

a :=

reg

-data[7:0]; if underflow then C := 0 else C := 1;

reg

:= a

Subs

reg1

reg2

reg3

C, V, Z, a

a :=

reg3

reg2

; if underflow then C := 0 else C := 1;

reg1

:= a

Subs

reg1

reg2

C, V, Z, a

a :=

reg1

reg2

; if underflow then C := 0 else C := 1;

reg1

:= a

Subs

reg

eaddr

C, V, Z, a

a :=

reg

DM(eaddr)

; if underflow then C := 0 else C := 1;

reg

:= a

Subsc

reg

,#data[7:0]

C, V, Z, a

a :=

reg

-data[7:0]-(1-C); if underflow then C := 0 else C := 1;

reg

:= a

Subsc

reg1

reg2

reg3

C, V, Z, a

a :=

reg3

reg2

-(1-C); if underflow then C := 0 else C := 1;

reg1

:= a

Subsc

reg1

reg2

C, V, Z, a

a :=

reg1

reg2

-(1-C); if underflow then C := 0 else C := 1;

reg1

:= a

Subsc

reg

eaddr

C, V, Z, a

a :=

reg

DM(eaddr)

-(1-C); if underflow then C := 0 else C := 1;

reg

:= a

Mul

reg

,#data[7:0]

u, u, u, a

a := (data[7:0]*

reg

)[7:0];

reg

:= (data[7:0]*

reg

)[15:8]

Mul

reg1

reg2

reg3

u, u, u, a

a := (

reg2

reg3

)[7:0];

reg1

:= (

reg2

reg3

)[15:8]

Mul

reg1

reg2

u, u, u, a

a := (

reg2

reg1

)[7:0];

reg1

:= (

reg2

reg1

)[15:8]

Mul

reg

eaddr

u, u, u, a

a := (

DM(eaddr)

reg

)[7:0];

reg

:= (

DM(eaddr)

reg

)[15:8]

Mula

reg

,#data[7:0]

u, u, u, a

a := (data[7:0]*

reg

)[7:0];

reg

:= (data[7:0]*

reg

)[15:8]

Mula

reg1

reg2

reg3

u, u, u, a

a := (

reg2

reg3

)[7:0];

reg1

:= (

reg2

reg3

)[15:8]

Mula

reg1

reg2

u, u, u, a

a := (

reg2

reg1

)[7:0];

reg1

:= (

reg2

reg1

)[15:8]

Mula

reg

eaddr

u, u, u, a

a := (

DM(eaddr)

reg

)[7:0];

reg

:= (

DM(eaddr)

reg

)[15:8]

Mshl

reg

,#shift[2:0]

u, u, u, a

a := (

reg

shift

)[7:0];

reg

:= (

reg

shift

)[15:8]

Mshr

reg

,#shift[2:0]

u, u, u, a

a := (

reg

(8-shift

)[7:0];

reg

:= (

reg

(8-shift

)[15:8]

Mshra

reg

,#shift[2:0]

u, u, u, a*

a := (

reg

(8-shift

)[7:0];

reg

:= (

reg

(8-shift

)[15:8]

Cmp

reg

,#data[7:0]

C, V, Z, a

a := data[7:0]-

reg

; if underflow then C :=0 else C:=1; V := C and (not Z)

Cmp

reg1

reg2

C, V, Z, a

a :=

reg2

reg1

; if underflow then C :=0 else C:=1; V := C and (not Z)

Cmp

reg

eaddr

C, V, Z, a

a :=

DM(eaddr)

reg

; if underflow then C :=0 else C:=1; V := C and (not Z)

Cmpa

reg

,#data[7:0]

C, V, Z, a

a := data[7:0]-

reg

; if underflow then C :=0 else C:=1; V := C and (not Z)

Cmpa

reg1

reg2

C, V, Z, a

a :=

reg2

reg1

; if underflow then C :=0 else C:=1; V := C and (not Z)

Cmpa

reg

eaddr

C, V, Z, a

a :=

DM(eaddr)

reg

; if underflow then C :=0 else C:=1; V := C and (not Z)

Tstb

reg

,#bit[2:0]

-, -, Z, a

a[bit] :=

reg[bit]

; other bits in a are 0

Setb

reg

,#bit[2:0]

-, -, Z, a

reg[bit]

:= 1; other bits unchanged; a :=

reg

Clrb

reg

,#bit[2:0]

-, -, Z, a

reg[bit]

:= 0; other bits unchanged; a :=

reg

Invb

reg

,#bit[2:0]

-, -, Z, a

reg[bit]

:= not

reg[bit]

; other bits unchanged; a :=

reg

3-6

D0304-40

Datasheet
XE88LC05/05A

Sflag

-,-,-, a

a[7] := C; a[6] := C xor V; a[5] := ST full; a[4] := ST empty

Rflag

reg

C, V, Z, a

a :=

reg

<< 1; ; a[0] := 0; C :=

reg[7]

Rflag

eaddr

C, V, Z, a

a :=

DM(eaddr)

<<1; a[0] :=0; C :=

DM(eaddr)[7]

Freq divn

-,-,-, -

reduces the CPU frequency (divn=nodiv, div2, div4, div8, div16)

Halt

-,-,-, -

halts the CPU

Nop

-,-,-,

operation

- = unchanged, u = undefined, *MSHR

reg

,# 1 doesn't shift by 1

Table 3-4. Instruction short reference

The Coolrisc816 has 8 different addressing modes. These modes are described in Table 3-5. In this
table, the notation ix refers to one of the data memory index registers i0, i1, i2 or i3. Using

eaddr

in an

instruction of Table 3-4 will access the data memory at the address

DM(eaddr)

and will

simultaneously execute the index operation.

extended address

eaddr

accessed data memory

location

DM(eaddr)

index

operation

addr[7:0] DM(h00&addr[7:0])

- direct

addressing

(ix) DM(ix)

indexed addressing

(ix, offset[7:0])

DM(ix+offset)

indexed addressing with immediate offset

(ix,r3) DM(ix+r3)

indexed addressing with register offset

(ix)+ DM(ix)

ix := ix+1

indexed addressing with index post-increment

(ix,offset[7:0])+ DM(ix+offset)

ix := ix+offset indexed addressing with index post-increment by the offset

-(ix) DM(ix-1)

ix := ix-1

indexed addressing with index pre-decrement

-(ix,offset[7:0]) DM(ix-offset)

ix := ix -offset indexed addressing with index pre-decrement by the offset

Table 3-5. Extended address mode description

Eleven different jump conditions are implemented as shown in Table 3-6. The contents of the column

in this table should replace the

notation in the instruction description of Table 3-4.

condition

C=1

C=0

Z=1

Z=0

V=1

V=0

(EV1 or EV0)=1

After CMP op1,op2

op1=op2

op1

op2

op1>op2

op1

op2

op1<op2

op1

op2

Table 3-6. Jump condition description

4-2

D0304-40

Datasheet
XE88LC05/05A

4.1 Memory

organisation

The XE88LC05 CPU is built with a Harvard architecture. The Harvard architecture uses separate
instruction and data memories. The instruction bus and data bus are also separated. The advantage
of such a structure is that the CPU can get a new instruction and read/write data simultaneously. The
circuit configuration is shown in Figure 4-1. The CPU has its 16 internal registers. The instruction
memory has a capacity of 8192 22-bit instructions. The data memory space has 8 low power
registers, the peripheral register space and 512 bytes of RAM.

Figure 4-1. Memory mapping

The CPU internal registers are described in the CPU chapter. A short reference of the low power
registers and peripheral registers is given in 4.2.

4.2 Quick reference data memory register map

The data register map is given in the tables below. A more detailed description of the different
registers is given in the detailed description of the different peripherals.

The tables give the following information:

1. The register name and register address
2. The different bits in the register
3. The access mode of the different bits (see Table 4-1 for code description)
4. The reset source and reset value of the different bits

0h027F

RAM

capacity:

512 bytes

0h0080

0h1FFF

Instruction

memory

capacity:

8k x 22bit

0h0000

CPU

CPU in

tern

al reg

i
sters

stat

iph

ipl

i3h

i3l

i2h

i2l

i1h

i1l

i0h

i0l

Low power

RAM

0h0000

0h007F

Peripheral

registers

0h0008

ta mem

o
r
y

d
a
t
a
bus

i
n
s
t
ruct

i
on bu

4-4

D0304-40

Datasheet
XE88LC05/05A

4.2.2

System, clock configuration and reset configuration (h0010-h001F)

Name

Address

RegSysCtrl

h0010

SleepEn

rw,0,cold

EnResPConf

rw,0,cold

EnBusError

rw,0,cold

EnResWD

rw,0,cold

RegSysReset

h0011

Sleep

rw,0,sys

ResetBusError

rc, 0, cold

ResetWD
rc, 0, cold

ResetfromportA

rc, 0, cold

ResPad

rc,0,cold

ResPadSleep

rc,0,cold

RegSysClock

h0012

CpuSel

rw,0,sleep

ExtClk

r,0,cold

EnExtClock

rw,0,cold

BiasRC

rw,1,cold

ColdXtal
r,1,sleep

ColdRC

r,1,sleep

EnableXtal

rw,0,sleep

EnableRC
rw,1,sleep

RegSysMisc

h0013

RCOnPA0

rw,0,sleep

DebFast

rw,0,sleep

OutputCkXtal

rw,0,sleep

OutputCpuCk

rw,0,sleep

RegSysWd

h0014

WatchDog[3:0]

s,0000,cold

RegSysPre0

h0015

ResPre
c1r0,0,-

RegSysRcTrim1

h001B

Reserved

rw,0,cold

RcFreqRange

rw,0,cold

RcFreqCoarse[3:0]

rw,0000,cold

RegSysRcTrim2

h001C

RcFreqFine[5:0]

rw,10000,cold

Table 4-4. Reset block and clock block registers

4.2.3

Port A (h0020-h0027)

Name

Address

RegPAIn

h0020

PAIn[7:0]

RegPADebounce

h0021

PADebounce[7:0]

rw,00000000,pconf

RegPAEdge

h0022

PAEdge[7:0]

rw,00000000,sys

RegPAPullup

h0023

PAPullup[7:0]

rw,00000000,pconf

RegPARes0

h0024

PARes0[7:0]

rw, 00000000, sys

RegPARes1

h0025

PARes1[7:0]

rw,00000000,sys

Table 4-5. Port A registers

4.2.4

Port B (h0028-h002F)

Name

Address

RegPBOut

h0028

PBOut[7:0]

rw,00000000,pconf

RegPBIn

h0029

PBIn[7:0]

RegPBDir

h002A

PBDir[7:0]

rw,00000000,pconf

RegPBOpen

h002B

PBOpen[7:0]

rw,00000000,pconf

RegPBPullup

h002C

PBPullup[7:0]

rw,00000000,pconf

RegPBAna

h002D

PBAna[3:0]

rw,0000,pconf

Table 4-6. Port B registers

4-5

D0304-40

Datasheet
XE88LC05/05A

4.2.5

Port C (h0030-h0033)

Name

Address

RegPCOut

h0030

PCOut[7:0]

rw,00000000,pconf

RegPCIn

h0031

PCIn[7:0]

r,-,-

RegPCDir

h0032

PD1Dir[7:0]

rw,00000000,pconf

Table 4-7. Port C registers

4.2.6

Flash programming (h0038-003B)

These four registers are used during flash programming only. Refer to the flash programming
algorithm documentation for more details.

4.2.7

Event handler (h003C-h003F)

Name

Address

RegEvn

h003C

CntIrqA

rc1,0,sys

CntIrqC

rc1,0,sys

128Hz

rc1,0,sys

PAEvn[1]

rc1,0,sys

CntIrqB

rc1,0,sys

CntIrqD

rc1,0,sys

1Hz

rc1,0,sys

PAEvn[0]

rc1,0,sys

RegEvnEn

h003D

EvnEn[7:0]

rw,00000000,sys

RegEvnPriority

h003E

EvnPriority[7:0]
r,11111111,sys

RegEvnEvn

h003F

EvnHigh

r,0,sys

EvnLow

r,0,sys

Table 4-8. Event handler registers

The origin of the different events is summarised in the table below.

Event

Event source

CntIrqA

Counter/Timer A (counter block)

CntIrqB

Counter/Timer B (counter block)

CntIrqC

Counter/Timer C (counter block)

CntIrqD

Counter/Timer D (counter block)

128Hz

Low prescaler (clock block)

1Hz

Low prescaler (clock block)

PAEvn[1:0] Port

Table 4-9. Event source description

4-6

D0304-40

Datasheet
XE88LC05/05A

4.2.8

Interrupt handler (h0040-h0047)

Name

Address

RegIrqHig

h0040

IrqAC

rc1,0,sys

128Hz

rc1,0,sys

CntIrqA

rc1,0,sys

CntIrqC

rc1,0,sys

UartIrqTx

rc1,0,sys

UartIrqRx

rc1,0,sys

RegIrqMid

h0041

UsrtCond1

rc1,0,sys

UrstCond2

rc1,0,sys

PAIrq[5]

rc1,0,sys

PAIrq[4]

rc1,0,sys

1Hz

rc1,0,sys

VldIrq

rc1,0,sys

PAIrq[1]

rc1,0,sys

PAIrq[0]

rc1,0,sys

RegIrqLow

h0042

PAIrq[7]

rc1,0,sys

PAIrq[6]

rc1,0,sys

CntIrqB

rc1,0,sys

CntIrqD

rc1,0,sys

PAIrq[3]

rc1,0,sys

PAIrq[2]

rc1,0,sys

RegIrqEnHig

h0043

IrqEnHig[7:0]

rw,0000000,sys

RegIrqEnMid

h0044

IrqEnMid[7:0]

rw,0000000,sys

RegIrqEnLow

h0045

IrqEnLow[7:0]

rw,0000000,sys

RegIrqPriority

h0046

IrqPriority[7:0]

r,11111111,sys

RegIrqIrq

h0047

IrqHig

r,0,sys

IrqMid

r,0,sys

IrqLow
r,0,sys

Table 4-10. Interrupt handler registers

The origin of the different interrupts is summarised in the table below.

Event

Event source

CntIrqA

Counter/Timer A (counter block)

CntIrqB

Counter/Timer B (counter block)

CntIrqC

Counter/Timer C (counter block)

CntIrqD

Counter/Timer D (counter block)

128Hz

Low prescaler (clock block)

1Hz

Low prescaler (clock block)

PAIrq[7:0] Port

UartIrqRx UART

reception

UartIrqTx

UART transmission

UrstCond1

USRT condition 1

UsrtCond2

USRT condition 2

VldIrq

Voltage level detector

IrqAC

Acquisition chain end of conversion interrupt

Table 4-11. Interrupt source description

4-7

D0304-40

Datasheet
XE88LC05/05A

4.2.9 USRT

(h0048-h004F)

Name

Address

RegUsrtS1

h0048

UsrtS1
s,1,sys

RegUsrtS0

h0049

UsrtS0
s,1,sys

RegUsrtCond1

h004A

UsrtCond1

rc,0,sys

RegUsrtCond2

h004B

UsrtCond2

rc,0,sys

RegUsrtCtrl

h004C

UsrtWaitS0

r,0,sys

UsrtEnWaitCond1

rw,0,sys

UsrtEnWaitS0

rw,0,sys

UsrtEnable

rw,0,sys

RegUsrtBufferS1

h004D

UsrtBufferS1

r,0,sys

RegUsrtEdgeS0

h004E

UsrtEdgeS0

r,0,sys

Table 4-12. USRT register description

4.2.10 UART

(h0050-h0057)

Name

Address

RegUartCtrl

h0050

UartEcho

rw,0,sys

UartEnRx1

rw,0,sys

UartEnTx

rw,0,sys

UartXRx

rw,0,sys

UartXTx
rw,0,sys

UartBR[2:0]

rw,101,sys

RegUartCmd

h0051

SelXtal

rw,0,sys

UartEnRx2

rw,0,sys

UartRcSel[2:0]

rw,000,sys

UartPM

rw,0,sys

UartPE

rw,0,sys

UartWL

rw,1,sys

RegUartTx

h0052

UartTx[7:0]

rw,0000000,sys

RegUartTxSta

h0053

UartTxBusy

r,0,sys

UartTxFull

r,0,sys

RegUartRx

h0054

UartRx[7:0]

r,00000000,sys

RegUartRxSta

h0055

UartRxSErr

r,0,sys

UartRxPErr

r,0,sys

UartRxFErr

r,0,sys

UartRxOerr

rc,0,sys

UartRxBusy

r,0,sys

UartRxFull

r,0,sys

Table 4-13. UART register description

4.2.11

Counter/Timer/PWM registers (h0058-h005F)

Name

Address

RegCntA

h0058

CounterA[7:0]

s,xxxxxxxx,-

RegCntB

h0059

CounterB[7:0]

s,xxxxxxxx,-

RegCntC

h005A

CounterC[7:0]

s,xxxxxxxx,-

RegCntD

h005B

CounterD[7:0]

s,xxxxxxxx,-

RegCntCtrlCk

h005C

CntDCkSel[1:0]

rw,xx,-

CntCCkSel[1:0]

rw,xx,-

CntBCkSel[1:0]

rw,xx,-

CntACkSel[1:0]

rw,xx,-

RegCntConfig1

h005D

CntDDownUp

rw,x,-

CntCDownUp

rw,x,-

CntBDownUp

rw,x,-

CntADownUp

rw,x,-

CascadeCD

rw,x,-

CascadeAB

rw,x,-

CntPWM1

rw,0,sys

CntPWM0

rw,0,sys

RegCntConfig2

h005E

CapSel[1:0]

rw,00,sys

CapFunc[1:0]

rw,00,sys

Pwm1Size[1:0]

rw,xx,-

Pwm0Size[1:0]

rw,xx,-

RegCntOn

h005F

CntDEnable

rw,0,sys

CntCEnable

rw,0,sys

CntBEnable

rw,0,sys

CntAEnable

rw,0,sys

Table 4-14. Counter/timer/PWM register description.

4-8

D0304-40

Datasheet
XE88LC05/05A

4.2.12

Acquisition chain registers (h0060-h0067)

Name

Address

RegAcOutLsb

h0060

OUT[7:0]

r,0,sys

RegAcOutMsb

h0061

OUT[15:8]

r,0,sys

RegAcCfg0

h0062

START

w r0,0,sys

SET_NELCONV[1:0]

rw,01,sys

SET_OSR[2:0]

rw,010,sys

CONT

rw,0,sys

RegAcCfg1

h0063

IB_AMP_ADC[1:0]

rw,11,sys

IB_AMP_PGA[1:0]

rw,11,sys

ENABLE[3:0]

rw,0000,sys

RegAcCfg2

h0064

FIN

rw,00,sys

PGA2_GAIN[1:0]

rw,00,sys

PGA2_OFFSET[3:0]

rw,0000,sys

RegAcCfg3

h0065

PGA1_GAIN

Rw,0,sys

PGA3_GAIN[6:0]

rw,0000000,sys

RegAcCfg4

h0066

PGA3_OFFSET

rw,0000000,sys

RegAcCfg5

h0067

BUSY

r,0,sys

DEF

w r0

AMUX[4:0]

rw,00000,sys

VMUX

rw,0,sys

Table 4-15. Acquisition chain register description.

4.2.13

Signal D/A registers (h0074-h0077)

Name

Address

RegDasInLsb

h0074

DasInLsb(7:0)

rw,00000000,sys

RegDasInMsb

h0075

DasInMsb(7:0)

rw,00000000,sys

RegDasCfg0

h0076

NsOrder(1:0)

rw,00,sys

CodeLmax(2:0)

rw,000,sys

Enable(1:0)

rw,00,sys

Fin

rw,0,sys

RegDasCfg1

h0077

rw,0,sys

Inv

rw,0,sys

Table 4-16. Signal D/A register description

4.2.14

Bias D/A registers (h0078-h0079)

Name

Address

RegDabIn

h0078

DabIn(7:0)

rw,00000000,sys

RegDabCfg

h0079

Enable(1:0)

rw,00,sys

Table 4-17. Bias D/A register description

4.2.15

Voltage multiplier (h007C)

Name

Address

RegVmultCfg0

h007C

Enable

rw,0,sys

Fin[1:0]

rw,00,sys

Table 4-18. VMULT register.

5-2

D0304-40

Datasheet
XE88LC05/05A

5.1 Overview

The XE8000 chips have three operating modes. There is the normal, the low current and the very low
current modes (see Figure 5-1). The different modes are controlled by the reset and clock blocks (see
the documentation of the respective blocks).

5.2 Operating

mode

Start-up
All bits are reset in the design when a POR (power-on-reset) is active.
RC is enabled, Xtal is disabled and the CPU is reset (pmaddr = 0000).
If Port A is used to return from the sleep mode, all bits with resetcold don't change (see sleep mode).

Reset
All bits with resetsystem and resetpconf (if enabled) are reset. Clock configuration doesn't change
except cpuck. The CPU is reset.

Active mode
This is the mode where the CPU and all peripherals can work and execute the embedded software.

Standby mode
Executing a HALT instruction moves the XE88LC05 into the Standby mode. The CPU is stopped, but
the clocks remain active. Therefore, the enabled peripherals remain active e.g. for time keeping. A
reset or an interrupt/event request (if enabled) cancels the standby mode.

Sleep mode
This is a very low-power mode because all circuit clocks and all peripherals are stopped. Only some
service blocks remain active. No time-keeping is possible. Two instructions are necessary to move
into sleep mode. First, the SleepEn (sleep enable) bit in RegSysCtrl has to be set to 1. The sleep
mode can then be activated by setting the Sleep bit in RegSysReset to 1.

There are three possibe ways to wake-up from the sleep mode:

1. The por (power-on-reset caused by a power-down followed by power-on). The RAM

information is lost.

2. The

padreset

3. The Port A reset combination (if the Port A is present in the product). See Port A

documentation for more details.

Note: If the Port A is used to return from the sleep mode, all bits with resetcold don't change

(RegSysCtrl, RegSysReset (except bit sleep), EnExtClock and BiasRc in RegSysClock,
RegSysRcTrim1 and RegSysRcTrim2). The SleepFlag bit in RegSysReset, reads back a 1
if the circuit was in sleep mode since the flag was last cleared (see reset block for more
details).

Note: For a lower power consumption, disable the BiasRc bit in RegSysClock before to going to

sleep mode. The start-up time of the oscillator will then be longer however.

Note: It is recommended to insert a NOP instruction after the instruction that sets the circuit in sleep

mode because this instruction can be executed when the sleep mode is left using the
resetfromportA.

6-2

D0304-40

Datasheet
XE88LC05/05A

6.1 Features

Power On Reset (POR)

External reset from the RESET pin

Programmable Watchdog timer reset

Programmable BusError reset

Sleep mode management

Programmable Port A input combination reset

6.2 Overview

The reset block is the reset manager. It handles the different reset sources and distributes them
through the system. It also controls the sleep mode of the circuit.

6.3 Register

map

Pos.

RegSysCtrl

Reset

Function

SleepEn

r w

0 resetcold

enables Sleep mode
0: sleep mode is disabled
1: sleep mode is enabled

EnResPConf

r w

0 resetcold

enables the resetpconf signal when the
resetglobal is active
0: resetpconf is disabled
1: resetpconf is enabled

EnBusError

r w

0 resetcold

enables reset from BusError
0: BusError reset source is disabled
1: BusError reset source is enabled

EnResWD

r w

0 resetcold

enables reset from Watchdog
0: Watchdog reset source is disabled
1: Watchdog reset source is enabled
this bit can not be set to 0 by SW

3 0

0000

unused

Table 6-1. RegSysCtrl register.

Pos.

RegSysReset

Reset

Function

Sleep

0 resetsystem

Sleep mode control (reads always 0)

6 -

r 0

unused

ResetBusError

r c

0 resetcold

reset source was BusError

ResetWD

r c

0 resetcold

reset source was Watchdog

ResetfromportA

r c

0 resetcold

reset source was Port A combination

ResPad

r c

0 resetcold

reset source was reset pad

ResPadSleep

r c

0 resetcold

reset source was reset pad in sleep mode

0 -

r 0

unused

Table 6-2. RegSysReset register

6-3

D0304-40

Datasheet
XE88LC05/05A

Pos.

RegSysWD

Reset

Function

7 4

0000

unused

WDKey[3] w

Watchdog Key bit 3

WDCounter[3] r

0 resetcold

Watchdog counter bit 3

WDKey[2] w

Watchdog Key bit 2

WDCounter[2] r

0 resetcold

Watchdog counter bit 2

WDKey[1] w

Watchdog Key bit 1

WDCounter[1] r

0 resetcold

Watchdog counter bit 1

WDKey[0] w

Watchdog Key bit 0

WDCounter[0] r

0 resetcold

Watchdog counter bit 0

Table 6-3. RegSysWD register

6.4 Reset handling capabilities

There are 5 reset sources:

· Power On Reset (POR)
· External reset from the RESET pin
· Programmable Port A input combination
· Programmable watchdog timer reset
· Programmable BusError reset on processor access outside the allocated memory map

Another reset source is the bit Sleep in the RegSysReset register. This source is fully controlled by
software and is only used during the sleep mode.

Four internal reset signals are generated from these sources and distributed through the system:

· resetcold:

is asserted on POR

· resetsystem: is asserted when resetcold or any other enabled reset source is active
· resetpconf: is asserted when resetsystem is active and if the

EnResPConf bit in the

RegSysCtrl register is set. This reset is generally used in the different ports.
It allows to maintain the port configuration unchanged while the rest of the
circuit is reset.

· resetsleep: is asserted when the circuit is in sleep mode

For the

circuits XE88LC01A and XE88LC05A

(2) For the circuits XE88LC01 and XE88LC05

Table 6-4 shows a summary of the dependency of the internal reset signals on the various reset
sources. In all the tables describing the different registers, the reset source is indicated.

Internal reset signals

resetpconf

Asserted
reset source

resetsystem

when

EnResPConf=0

when

EnResPConf=1

resetsleep

resetcold

POR Asserted

Asserted

RESET pin (1)

Asserted

Asserted Asserted

Asserted

RESET pin (2)

Asserted

PortA input

Asserted

Watchdog Asserted

Asserted -

BusError Asserted -

Asserted - -

Sleep -

- -

Asserted

(1) For the circuits XE88LC01A and XE88LC05A

(2) For the circuits XE88LC01 and XE88LC05

Table 6-4. Internal reset assertion as a function of the reset source.

6-4

D0304-40

Datasheet
XE88LC05/05A

6.5 Reset source description

6.5.1

Power On Reset

The power on reset (POR) monitors the external supply voltage. It activates a reset on a rising edge
of this supply voltage. The reset is inactivated only if the internal voltage regulator has started up. No
precise voltage level detection is performed by the POR block.

6.5.2 RESET

pin

The reset can be activated by applying a high input state on the RESET pin.

6.5.3

Programmable Port A input combination

A reset signal can be generated by Port A. See the description of the Port A for further information.

6.5.4 Watchdog

reset

The Watchdog will generate a reset if the

EnResetWD

bit in the RegSysCtrl register has been set and

if the watchdog is not cleared in time by the processor. See chapter 6.7 describing the watchdog for
further information.

6.5.5 BusError

reset

The address space is assigned as shown in the register map of the product. If the

EnBusError

bit in

the RegSysCtrl register is set and a non-existant address is accessed by the software, a reset is
generated.

6.5.6 Sleep

mode

Entering the sleep mode will reset a part of the circuit. The reset is used to configure the circuit for
correct wake-up after the sleep mode. If the SleepEn bit in the RegSysCtrl register has been set, the
sleep mode can be entered by setting the bit Sleep in RegSysReset. During the sleep mode, the
resetsleep signal is active. For detailed information on the sleep mode, see the system
documentation.

6.6 Control register description and operation

Two registers are dedicated for reset status and control, RegSysReset and RegSysCtrl. The bits
Sleep, and SleepEn are also located in those registers and are described in the chapter dedicated to
the different operating modes of the circuit (system block).

The RegSysReset register gives information on the source which generated the last reset. It can be
read at the beginning of the application program to detect if the circuit is recovering from an error or
exception condition, or if the circuit is starting up normally.

· when ResBusError is 1, a forbidden address access generated the reset.
· when ResWD is 1, the watchdog generated the reset.
· when ResPortA is 1, a PortA combination generated the reset.
· when ResPad is 1, a reset pin generated the reset.
· when ResPadSleep is 1, a reset pin in sleep mode generated the reset.

Note: If no bit is set to 1, the reset source was the internal POR.
Note: Several bits might be set or not, if the register was not cleared in between 2 reset
occurrences. Write any value in RegSysReset to clear it.

6-5

D0304-40

Datasheet
XE88LC05/05A

Note: When a reset pin wakes up the chip from the sleep mode, ResPad and ResPadSleep
bits are equal at 1.

The last bit concerns the sleep mode control (see system documentation for the sleep mode
description).

· when Sleep is set to 1, and SleepEn is 1, the sleep mode is entered. The bit always reads
back a 0.

The RegSysCtrl register enables the different available reset sources and the sleep mode.

· EnResWD enables the reset due to the watchdog (can not be disabled once enabled).
· EnBusError enables the reset due to a bus error condition.
· EnResPConf enables the reset of the port configurations when reset by Port A, a Bus Error

or the watchdog.

· SleepEn unlocks the Sleep bit. As long as SleepEn is 0, the Sleep bit has no effect.

6.7 Watchdog

The watchdog is a timer which has to be cleared at least every 2 seconds by the software to prevent a
reset being generated by the timeout condition.

The watchdog can be enabled by software by setting the EnResWD bit in the RegSysCtrl register to
1. It can then only be disabled by a power on reset.

The watchdog timer can be cleared by writing consecutively the values Hx0A and Hx03 to the
RegSysWD register. The sequence must strictly be respected to clear the watchdog.

In assembler code, the sequence to clear the watchdog is:

move AddrRegSysWD, #0x0A
move AddrRegSysWD, #0x03

Only writing Hx0A followed by Hx03 resets the WD. If some other write instruction is done to the
RegSysWD between the writing of the Hx0A and Hx03 values, the watchdog timer will not be cleared.

It is possible to read the status of the watchdog in the RegSysWD register. The watchdog is a 4 bit
counter with a count range between 0 and 7. The system reset is generated when the counter is
reaching the value 8.

6.8 Start-up and watchdog specifications

At start-up of the circuit, the POR (power-on-reset) block generates a reset signal during t

POR

. The

circuit starts software execution after this period (see system chapter). The POR is intended to force
the circuit in a correct state at start-up. For precise monitoring of the supply voltage, the voltage level
detector (VLD) has to be used.

7-2

D0304-40

Datasheet
XE88LC05/05A

7.1 Features

3 available clock sources (RC oscillator, quartz oscillator and external clock).

2 divider chains: high-prescaler (8 bits) and low-prescaler (15 bits).

CPU clock disabling in halt mode.

7.2 Overview

The XE88LC05 chips can work on different clock sources (RC oscillator, quartz oscillator and external
clock). The clock generator block is in charge of distributing the necessary clock frequencies to the
circuit. Figure 7-1 represents the functionality of the clock block.

The internal RC oscillator drives the high prescaler. This prescaler generates frequency divisions
down to 1/256 of its input frequency. A 32kHz clock is generated by enabling the quartz oscillator (if
present in the product) or by selecting the appropriate tap on the high prescaler. The low prescaler
generates clock signals from 32kHz down to 1Hz. The clock source for the CPU can be selected from
the RC oscillator, the external clock or the 32kHz clock.

7.3 Register

map

pos.

RegSysClock

Reset

function

CpuSel

rw 0 resetsleep Select speed for cpuck, 0=RC, 1=xtal or

external clock

6 Extclk

r 0

resetcold

External clock detected, 1=available

EnExtClock

0 resetcold

Enable for external clock, 1=enabled

BiasRc

1 resetcold

Enable Rcbias (reduces start-up time of RC).

ColdXtal

1 resetsleep

Xtal in start phase

ColdRC

1 resetsleep

RC in start phase

EnableXtal

0 resetsleep

Enable Xtal oscillator, 0=disabled, 1=enabled

EnableRc

1 resetsleep

Enable RC oscillator, 0=disabled, 1=enabled

Table 7-1: RegSysClock register

pos.

RegSysMisc

Reset

Function

7-4 --

r 0000

Unused

RCOnPA0

0 resetsleep

Start RC on PA[0], 0=disabled, 1=enabled

2 DebFast

resetsleep

Debouncer clock speed, 0=256Hz, 1=8kHz

1 OutputCkXtal rw

resetsleep

Output Xtal Clock on PB[3], 0=disabled,
1=enabled if EnXtal=1 else PB[3]=0

0 OutputCpuCk rw

resetsleep

Output CPU clock on PB[2], 0=disabled,
1=enabled

Table 7-2: RegSysMisc register

pos.

RegSysPre0

reset

Function

7-1 --

r 0000000

Unused

0 ResPre

w1
r0

Write 1 to reset low prescaler, but always
reads 0

Table 7-3: RegSysPre0 register

7-3

D0304-40

Datasheet
XE88LC05/05A

pos.

RegSysRcTrim1

reset

Function

7-4 --

r 00

Unused

5 Reserved

resetcold

Reserved

RcFreqRange

0 resetcold

Low/high freq. range (low=0)

RcFreqCoarse[3]

0 resetcold

RC coarse trim bit 3

RcFreqCoarse[2]

0 resetcold

RC coarse trim bit 2

RcFreqCoarse[1]

0 resetcold

RC coarse trim bit 1

RcFreqCoarse[0]

0 resetcold

RC coarse trim bit 0

Table 7-4: RegSysRCTrim1 register

pos.

RegSysRcTrim2

reset

function

7-6 --

r 00

Unused

RcFreqFine[5]

1 resetcold

RC fine trim bit 5

RcFreqFine[4]

0 resetcold

RC fine trim bit 4

RcFreqFine[3]

0 resetcold

RC fine trim bit 3

RcFreqFine[2]

0 resetcold

RC fine trim bit 2

RcFreqFine[1]

0 resetcold

RC fine trim bit 1

RcFreqFine[0]

0 resetcold

RC fine trim bit 0

Table 7-5: RegSysRCTrim2 register

OSCIN

Xtal

High prescaler

CpuCk

CpuSel

RegSysRcTrim1
RegSysRcTrim2

CkRc

CkXtal

EnXtal and
not(ExtClk or EnExtClk)

Low prescaler

32kHz

1Hz

CkRc

CkRc/256

External
Clock

Figure 7-1. Clock block structure

7.4 Interrupts and events map

Interrupt

Interrupt source

Mapping in the interrupt manager Mapping in the event manager

IrqPre1 Ck128Hz

RegIrqHig(6)

RegEvn(5)

IrqPre2 Ck1Hz

RegIrqMid(3)

RegEvn(1)

Table 7-6: Interrupts and events map

7-4

D0304-40

Datasheet
XE88LC05/05A

7.5 Clock

sources

7.5.1 RC

oscillator

7.5.1.1 Configuration

The RC oscillator is always turned on and selected for CPU and system operation at power-on reset
and when exiting sleep mode. It can be turned off after the Xtal (quartz oscillator) has been started,
after selection of the external clock or by entering sleep mode.
The RC oscillator has two frequency ranges: sub-MHz (100 kHz to 1 MHz) and above-MHz (1 MHz to
10 MHz). Inside a range, the frequency can be tuned by software for coarse and fine adjustment. See
registers RegSysRcTrim1 and RegSysRcTrim2.

Bit EnableRC in register RegSysClock controls the propagation of the RC clock signal and the
operation of the oscillator. The user can stop the RC oscillator by resetting the bit EnableRC. Entering
the sleep mode disables the RC oscillator.

Note: Before turning off the RC oscillator, the cpusel bit in RegSysClock must be set to one.

Note: The RC oscillator bias can be maintained while the oscillator is switched off by setting the bit
BiasRc in RegSysClock. This allows a faster restart of the RC oscillator at the cost of increased
power consumption when the oscillator is disabled (see section 7.5.1.3).

7.5.1.2

RC oscillator frequency tuning

The RC oscillator frequency can be set using the bits in the RegSysRcTrim1 and RegSysRcTrim2
registers. Figure 7-2 shows the nominal frequency of the RC oscillator as a function of these bits. The
absolute value of the frequency for a given register content may change by

50% from chip to chip

due to the tolerances on the integrated capacitors and resistors. However, the modification of the
frequency as a function of a modification of the register content is fairly precise for frequencies below
2MHz. This means that the curves in Figure 7-2 can shift up and down but that the slope remains
unchanged.

The bit RcFreqRange modifies the oscillator frequency by a factor of 10. The upper curve in the
figure corresponds to RcFreqRange=1.

The RcFreqCoarse modifies the frequency of the oscillator by a factor (RcFreqCoarse+1). The figure
represents the frequency for 5 different values of the bits RcFreqCoarse: for each value the
frequency is multiplied by 2.

Incrementing the RcFreqFine code increases the frequency by about 1.4%.

The frequency of the oscillator is therefor given by:

Rcmin

(1+9

RcFreqRange)

(1+RcFreqCoarse)

(1.014)

RcFreqFine

with f

Rcmin

the RC oscillator frequency if the registers are all 0. At higher frequencies, the frequency

may deviate from the value predicted by the equation.

7-5

D0304-40

Datasheet
XE88LC05/05A

000

100

010

000

100

111

000

0000

0001

0011

0111

1111

1E+04

1E+05

1E+06

1E+07

1E+08

RcFreqCoarse(3:0)

Nominal RC oscillator frequency [Hz]

RcFreqRange='1'
RcFreqRange='0'

RcFreqFine(5:0)

Figure 7-2. RC oscillator nominal frequency tuning.

7.5.1.3

RC oscillator specifications

symbol

description

min

typ

max

unit

Comments

RCmin

Lowest RC frequency

120

kHz

Note 1

RcFreqFine

fine tuning step

1.4

2.0

RC_su startup

time

BiasRc=0

BiasRc=1

PSRR @ DC Supply voltage

TBD

%/V

Note 2

dependence

TBD

%/V

Note

Temperature
dependence

0.1

Table 7-7. RC oscillator specifications

Note 1: this is the frequency tolerance when all trimming codes are 0.

Note 2: frequency shift as a function of VBAT with normal regulator function.

Note 3: frequency shift as a function of VBAT while the regulator is short-circuited to VBAT.

The tolerances on the minimal frequency and the drift with supply or temperature can be cancelled
using the software DFLL (digital frequency locked loop) which uses the crystal oscillator as a
reference frequency.

7-6

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XE88LC05/05A

7.5.2 Xtal

oscillator

7.5.2.1 Xtal

configuration

The Xtal operates with an external crystal of 32'768 Hz.

During Xtal oscillator start-up, the first 32768 cycles are masked. The two bits EnableXtal and
ColdXtal in register RegSysClock control the oscillator.

At power-on reset or during sleep mode, EnableXtal is reset and ColdXtal is set (Xtal oscillator is not
selected at start-up). The user can start Xtal oscillator by setting EnableXtal. When the Xtal oscillator
starts, bit ColdXtal is reset after 32768 cycles. Before ColdXtal is reset by the system, the Xtal
frequency precision is not guaranteed. The Xtal oscillator can be stopped by the user by resetting bit
EnableXtal.

When the user enters into sleep mode, the Xtal is stopped.

When an external clock is detected (ExtClk = 1) or the EnExtClock is set 1, the EnableXtal bit can
not be set to 1.

7.5.2.2

Xtal oscillator specifications

The crystal oscillator has been designed for a crystal with the specifications given in Table 7-8. The
oscillator precision can only be guaranteed for this crystal.

Symbol

Description

Min

Typ

Max

Unit

Comments

Fs Resonance

frequency

32768

CL for nominal
frequency

8.2 15

Rm Motional

resistance 40 100

Cm Motional

capacitance 1.8 2.5 3.2

C0 Shunt

capacitance

0.7 1.1 2.0

Rmp Motional

resistance

overtone (parasitic)

4 8

Q Quality

factor

30k

50k

400k

Table 7-8. Crystal specifications.

For safe operation, low power consumption and to meet the specified precision, careful board layout
is required:

Keep lines OSCIN and OSCOUT short and insert a VSS line in between them.

Connect the crystal package to VSS.

No noisy or digital lines near OSCIN or OSCOUT.

Insert guards where needed.

Respect the board specifications of Table 7-9.

Symbol

Description

Min

Typ

Max

Unit

Comments

Rh_oscin

Resistance OSCIN-VSS

Rh_oscout

Resistance OSCOUT-VSS

Rh_

oscin_oscout

Resistance OSCIN-OSCOUT

Cp_oscin

Capacitance OSCIN-VSS

0.5 3.0

Cp_oscout

Capacitance OSCOUT-VSS

0.5 3.0

Cp_

oscin_oscout

Capacitance OSCIN-OSCOUT

0.2 1.0

Table 7-9. Board layout specifications.

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The oscillator characteristics are given in Table 7-10. The characteristics are valid only if the crystal
and board layout meet the specifications above.

Symbol

Description

Min

Typ

Max

Unit

Comments

Xtal

Nominal frequency

32768

St_xtal Start-up

time

Fstab

Frequency deviation

-100

300

ppm

Note 1

Table 7-10. Crystal oscillator characteristics.

Note 1. This gives the relative frequency deviation from nominal for a crystal with CL=8.2pF and
within the temperature range -40

C to 85

C. The crystal tolerance, crystal aging and crystal

temperature drift are not included in this figure.

7.5.3 External

clock

7.5.3.1

External clock configuration

The user can provide an external clock instead of the internal oscillators. Only the CPU can use the
external clock. The external clock input pin is OSCIN.

The system is configured for external clock by bit EnExtClock in register RegSysClock.

When EnExtClock is set to 1, the external clock is detected after 4 pulses on pin OSCIN. The ExtClk
bit shows when the external clock is available.

Note: when using the external clock, the Xtal is not available.

7.5.3.2

External clock specification

The external clock has to satisfy the specifications in the table below. Correct behavior of the circuit
can not be guaranteed if the external clock signal does not respect the specifications below.

Symbol

Description

Min

Typ

Max

Unit

Comments

EXT

External clock
frequency

MHz

PW_1

Pulse 1 width

0.2

PW_0

Pulse 0 width

0.2

Table 7-11. External clock specifications.

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7.6 Clock source selection

There are three possible clock sources available for the CPU clock. The RC clock is always selected
after power-up or after Sleep mode. The CPU clock selection is done with the bit CpuSel in
RegSysClock (0= RC clock, 1= 32 kHz from Xtal if EnableXtal =1, ExtClk = 0 and EnExtClk = 0
else external clock).

Switching from one clock source to another is glitch free.

The next table summarizes the different clock configurations of the circuit:

Clock Sources

Clock targets

Cpuck

Note 1

Mode
name

EnExtClk

EnableRc

EnableXtal

CpuSel=0

CpuSel=1

High

Prescaler

Clock

input

Low

Prescaler

Clock

input

Sleep

0 0 0

Off

Xtal

0 0 1

Off

Xtal

Off

Xtal

0 1 0

RC RC

High

presc.

RC + Xtal

0 1 1

Xtal RC

Xtal

External 1 0 X Off External Off

Off

RC +
External

1 1 X

External RC High

presc.

Table 7-12: Table of clocking modes.

Note 1: The CPU clock can be divided by using the freq instruction (see coolrisc instruction set)

Switching from one clock source to another and stopping the unused clock source must be performed
using 3 MOVE instructions to RegSysClock. First select the new clock source, secondly change the
CpuSel bit and finally stop the unused one.

7.7 RegSysMisc

Description

The RCOnPA0 bit in RegSysMisc can be used to enable the RC oscillator on an event external to
the circuit. If RCOnPA0 is 1, the RC oscillator is enabled (EnableRC bit is set to 1) as soon as the
value on port A pin PA[0] is equal to 1. The port A pin can be debounced (see port A documentation).

Bit DebFast in the RegSysMisc register allows to chose the debouncer clock between 256Hz and
8kHz (DebFast = 0 and DebFast = 1 respectively). The Debouncer clock is used to debounce PA
inputs (see port A documentation).

Bit OutputCkXtal allows to show the Xtal clock on PB[3]. The EnableXtal bit must be set to 1 else
PB[3] equals 0 (see port B documentation to set up the port B).

Bit OutputCpuCk allows to show the CpuClock on PB[2] (see port B documentation).

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8.1 Features

The XE8000 chips support 24 interrupt sources, divided into 3 levels of priority.

8.2 Overview

A CPU interruption is generated and memorized when an interrupt becomes active. The 24 interrupt
sources are divided into 3 levels of priority: High (8 interrupt sources), Mid (8 interrupt sources), and
Low (8 interrupt sources). Those 3 levels of priority are directly mapped to those supported by the
CoolRisc® (IN0, IN1 and IN2; see CoolRisc® documentation for more information).

RegIrqHig, RegIrqMid, and RegIrqLow are 8-bit registers containing flags for the interrupt sources.
Those flags are set when the interrupt is enabled (i.e. if the corresponding bit in the registers
RegIrqEnHig, RegIrqEnMid or RegIrqEnLow is set) and a rising edge is detected on the
corresponding interrupt source.

Once memorized, an interrupt flag can be cleared by writing a `1' in the corresponding bit of
RegIrqHig, RegIrqMid or RegIrqLow. Writing a `0' does not modify the flag. To definitively clear the
interrupt, one has to clear the CoolRisc interrupt in the CoolRisc status register. All interrupts are
automatically cleared after a reset.

Two registers are provided to facilitate the writing of interrupt service software. RegIrqPriority
contains the number of the highest priority interrupt set (its value is 0xFF when no interrupt is set).
RegIrqIrq indicates the priority level of the current interrupts. RegIrqIrq and RegIrqPriority `s values
are dependent upon the memorized state of the interrupts (as reflected in flags in RegIrqHig,
RegIrqMid and RegIrqLow).

8.3 Register

map

pos.

RegIrqHig

reset

function

7 RegIrqHig[7] r

0 resetsystem

interrupt #23 (high priority)
clear interrupt #23 when 1 is written

6 RegIrqHig[6] r

0 resetsystem

interrupt #22 (high priority)
clear interrupt #22 when 1 is written

5 RegIrqHig[5] r

0 resetsystem

interrupt #21 (high priority)
clear interrupt #21 when 1 is written

4 RegIrqHig[4] r

0 resetsystem

interrupt #20 (high priority)
clear interrupt #20 when 1 is written

3 RegIrqHig[3] r

0 resetsystem

interrupt #19 (high priority)
clear interrupt #19 when 1 is written

2 RegIrqHig[2] r

0 resetsystem

interrupt #18 (high priority)
clear interrupt #18 when 1 is written

1 RegIrqHig[1] r

0 resetsystem

interrupt #17 (high priority)
clear interrupt #17 when 1 is written

0 RegIrqHig[0] r

0 resetsystem

interrupt #16 (high priority)
clear interrupt #16 when 1 is written

Table 8-1: RegIrqHig

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XE88LC05/05A

pos.

RegIrqMid

reset

function

7 RegIrqMid[7] r

0 resetsystem

interrupt #15 (mid priority)
clear interrupt #15 when 1 is written

6 RegIrqMid[6] r

0 resetsystem

interrupt #14 (mid priority)
clear interrupt #14 when 1 is written

5 RegIrqMid[5] r

0 resetsystem

interrupt #13 (mid priority)
clear interrupt #13 when 1 is written

4 RegIrqMid[4] r

0 resetsystem

interrupt #12 (mid priority)
clear interrupt #12 when 1 is written

3 RegIrqMid[3] r

0 resetsystem

interrupt #11 (mid priority)
clear interrupt #11 when 1 is written

2 RegIrqMid[2] r

0 resetsystem

interrupt #10 (mid priority)
clear interrupt #10 when 1 is written

1 RegIrqMid[1] r

0 resetsystem

interrupt #9 (mid priority)
clear interrupt #9 when 1 is written

0 RegIrqMid[0] r

0 resetsystem

interrupt #8 (mid priority)
clear interrupt #8 when 1 is written

Table 8-2: RegIrqMid

pos.

RegIrqLow

reset

function

7 RegIrqLow[7] r

0 resetsystem

interrupt #7 (low priority)
clear interrupt #7 when 1 is written

6 RegIrqLow[6] r

0 resetsystem

interrupt #6 (low priority)
clear interrupt #6 when 1 is written

5 RegIrqLow[5] r

0 resetsystem

interrupt #5 (low priority)
clear interrupt #5 when 1 is written

4 RegIrqLow[4] r

0 resetsystem

interrupt #4 (low priority)
clear interrupt #4 when 1 is written

3 RegIrqLow[3] r

0 resetsystem

interrupt #3 (low priority)
clear interrupt #3 when 1 is written

2 RegIrqLow[2] r

0 resetsystem

interrupt #2 (low priority)
clear interrupt #2 when 1 is written

1 RegIrqLow[1] r

0 resetsystem

interrupt #1 (low priority)
clear interrupt #1 when 1 is written

0 RegIrqLow[0] r

0 resetsystem

interrupt #0 (low priority)
clear interrupt #0 when 1 is written

Table 8-3: RegIrqLow

pos.

RegIrqEnHig

reset

function

RegIrqEnHig[7]

0 resetsystem

1= enable interrupt #23

RegIrqEnHig[6]

0 resetsystem

1= enable interrupt #22

RegIrqEnHig[5]

0 resetsystem

1= enable interrupt #21

RegIrqEnHig[4]

0 resetsystem

1= enable interrupt #20

RegIrqEnHig[3]

0 resetsystem

1= enable interrupt #19

RegIrqEnHig[2]

0 resetsystem

1= enable interrupt #18

RegIrqEnHig[1]

0 resetsystem

1= enable interrupt #17

RegIrqEnHig[0]

0 resetsystem

1= enable interrupt #16

Table 8-4: RegIrqEnHig

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XE88LC05/05A

pos.

RegIrqEnMid

reset

function

RegIrqEnMid[7]

0 resetsystem

1= enable interrupt #15

RegIrqEnMid[6]

0 resetsystem

1= enable interrupt #14

RegIrqEnMid[5]

0 resetsystem

1= enable interrupt #13

RegIrqEnMid[4]

0 resetsystem

1= enable interrupt #12

RegIrqEnMid[3]

0 resetsystem

1= enable interrupt #11

RegIrqEnMid[2]

0 resetsystem

1= enable interrupt #10

RegIrqEnMid[1]

0 resetsystem

1= enable interrupt #9

RegIrqEnMid[0]

0 resetsystem

1= enable interrupt #8

Table 8-5: RegIrqEnMid

pos.

RegIrqEnLow

reset

function

RegIrqEnLow[7]

0 resetsystem

1= enable interrupt #7

RegIrqEnLow[6]

0 resetsystem

1= enable interrupt #6

RegIrqEnLow[5]

0 resetsystem

1= enable interrupt #5

RegIrqEnLow[4]

0 resetsystem

1= enable interrupt #4

RegIrqEnLow[3]

0 resetsystem

1= enable interrupt #3

RegIrqEnLow[2]

0 resetsystem

1= enable interrupt #2

RegIrqEnLow[1]

0 resetsystem

1= enable interrupt #1

RegIrqEnLow[0]

0 resetsystem

1= enable interrupt #0

Table 8-6: RegIrqEnLow

pos.

RegIrqPriority

reset

function

7-0 RegIrqPriority r 11111111

resetsystem

code of highest priority set

Table 8-7: RegIrqPriority

pos.

RegIrqIrq

Reset

function

7-3 -

r 00000

unused

IrqHig

0 resetsystem

one or more high priority interrupt is
set

IrqMid

0 resetsystem

one or more mid priority interrupt is
set

IrqLow

0 resetsystem

one or more low priority interrupt is
set

Table 8-8: RegIrqIrq

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9.1 Features

The XE8000 chips support 8 event sources, divided into 2 levels of priority.

9.2 Overview

A CPU event is generated and memorized when an event source becomes active. The 8 event
sources are divided into 2 levels of priority: High (4 event sources) and Low (4 event sources). Those
2 levels of priority are directly mapped to those supported by the CoolRisc (EV0 and EV1; see
CoolRisc documentation for more information).

RegEvn is an 8-bit register containing flags for the event sources. Those flags are set when the event
is enabled (i.e. if the corresponding bit in the registers RegEvnEn is set) and a rising edge is detected
on the corresponding event source.

Once memorized, writing a `1' in the corresponding bit of RegEvn clears an event flag. Writing a `0'
does not modify the flag. All interrupts are automatically cleared after a reset.

Two registers are provided to facilitate the writing of event service software. RegEvnPriority contains
the number of the highest priority event set (its value is 0xFF when no event is set). RegEvnEvn
indicates the priority level of the current interrupts. RegEvnEvn and RegEvnPriority `s values are
dependent upon the memorized state of the events (as reflected in flags in RegEvn).

9.3 Register

map

pos.

RegEvn

reset

function

7 RegEvn[7]

r
c1

0 resetsystem

event #7 (high priority)
clear event #7 when written 1

6 RegEvn[6]

r
c1

0 resetsystem

event #6 (high priority)
clear event #6 when written 1

5 RegEvn[5]

r
c1

0 resetsystem

event #5 (high priority)
clear event #5 when written 1

4 RegEvn[4]

r
c1

0 resetsystem

event #4 (high priority)
clear event #4 when written 1

3 RegEvn[3]

r
c1

0 resetsystem

event #3 (low priority)
clear event #3 when written 1

2 RegEvn[2]

r
c1

0 resetsystem

event #2 (low priority)
clear event #2 when written 1

1 RegEvn[1]

r
c1

0 resetsystem

event #1 (low priority)
clear event #1 when written 1

0 RegEvn[0]

r
c1

0 resetsystem

event #0 (low priority)
clear event #0 when written 1

Table 9-1: RegEvn

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10.1 Features

Low power RAM locations.

10.2 Overview

In order to save power consumption, 8 8-bit registers are provided in page 0. These memory locations
should be reserved for often-updated variables. Accessing these register locations requires much less
power than the other general purpose RAM locations.

10.3 Register map

pos.

Reg00

reset

function

7-0 Reg00

rw XXXXXXXX

low-power data memory

Table 10-1: Reg00

pos.

Reg01

reset

function

7-0 Reg01

rw XXXXXXXX

low-power data memory

Table 10-2: Reg01

pos.

Reg02

reset

function

7-0 Reg02

rw XXXXXXXX

low-power data memory

Table 10-3: Reg02

pos.

Reg03

reset

function

7-0 Reg03

rw XXXXXXXX

low-power data memory

Table 10-4: Reg03

pos.

Reg04

reset

function

7-0 Reg04

rw XXXXXXXX

low-power data memory

Table 10-5: Reg04

pos.

Reg05

reset

function

7-0 Reg05

rw XXXXXXXX

low-power data memory

Table 10-6: Reg05

pos.

Reg06

¨reset

function

7-0 Reg06

rw XXXXXXXX

low-power data memory

Table 10-7: Reg06

pos.

Reg07

reset

function

7-0 Reg07

rw XXXXXXXX

low-power data memory

Table 10-8: Reg07

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11.3 Register map

There are six registers in the Port A (PA), namely RegPAIn, RegPADebounce, RegPAEdge,
RegPAPullup, RegPARes0 and RegPARes1. Table 11-1 to Table 11-6 show the mapping of control
bits and functionality.

pos.

RegPAIn

reset

description

7:0

PAIn[7:0]

pad PA[7] to PA[0] input value

Table 11-1: RegPAIn

pos.

RegPADebounce

reset

description

7:0 PADebounce[7:0]

00000000

resetpconf

PA[7] to PA[0]

1: debounce enabled

0: debounce disabled

Table 11-2: RegPADebounce

pos.

RegPAEdge

reset

description

7:0 PAEdge[7:0]

00000000

resetsystem

PA[7] to PA[0] edge configuration

0: positive edge

1: negative edge

Table 11-3: RegPAEdge

pos.

RegPAPullup

reset

description

7:0 PAPullup[7:0]

00000000

resetpconf

PA[7] to PA[0] pullup enable

0: pullup disabled

1: pullup enabled

Table 11-4: RegPAPullup

pos.

RegPARes0

Reset

description

7:0 PARes0[7:0]

00000000

resetsystem

PA[7] to PA[0] reset configuration

Table 11-5: RegPARes0

pos.

RegPARes1

reset

Description

7:0 PARes1[7:0]

w 00000000

resetsystem

PA[7] to PA[0] reset configuration

Table 11-6: RegPARes

11.4 Interrupts and events map

Interrupt source

Default mapping in

the interrupt manager

Default mapping in the

event manager

pa_irqbus[5] RegIrqMid[5]

pa_irqbus[4] RegIrqMid[4]

pa_irqbus[1] RegIrqMid[1]

RegEvn[4]

pa_irqbus[0] RegIrqMid[0]

RegEvn[0]

pa_irqbus[7] RegIrqLow[7]

pa_irqbus[6] RegIrqLow[6]

pa_irqbus[3] RegIrqLow[3]

pa_irqbus[2] RegIrqLow[2]

11-4

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11.5 Port A (PA) Operation

The Port A input status (debounced or not) can be read from RegPAin.

Debounce mode:
Each bit in Port A can be individually debounced by setting the corresponding bit in
RegPADebounce. After reset, the debounce function is disabled. After enabling the debouncer, the
change of the input value is accepted only if the input value is identical at two consecutive sampling
on the rising edge of the selected clock. Selection of the clock is done by the bit DebFast in Register
RegSysMisc (see clock block documentation for more precision on the frequency).

DebFast

Clock filter

0 256

1 8

kHz

Table 11-7: debounce frequency selection

Figure 11-2: digital debouncer

Pull-ups:
When the corresponding bit in RegPAPullup is set to 0, the inputs are floating (pull-up resistors are
disconnected). When the corresponding bit in RegPAPullup is set to 1, a pull-up resistor is connected
to the input pin. Port A starts up with the pull-up resistors disconnected.

Port A as an interrupt source:
Each Port A input is an interrupt request source and can be set on rising or falling edge with the
corresponding bit in RegPAEdge. After reset, the rising edge is selected for interrupt generation by
default. The interrupt source can be debounced by setting register RegPADebounce.

Note: care must be taken when modifying RegPAEdge because this register performs an edge
selection. The change of this register may result in a transition which may be interpreted as a valid
interruption.

Port A as an event source:
The interrupt signals of the pins PA[0] and PA[1] are also available as events on the event controller.

Port A as a clock source (product dependent):
Images of the PA[0] to PA[3] input ports (debounced or not) are available as clock sources for the
counter/timer/PWM peripheral (see the counter block documentation for more information).

Port A as a reset source:
Port A can be used to generate a system reset by placing a predetermined word on Port A externally.
The reset is built using a logical and of the 8 PARes[x] signals:

resetfromportA = PAReset[7] AND PAReset[6] AND PAReset[5] AND ... AND PAReset[0]

Input

CkDebounce

Debounced

11-5

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XE88LC05/05A

PAReset[x] is itself a logical function of the corresponding pin PA[x]. One of four logical functions can
be selected for each pin by writing into two registers RegPARes0 and RegPARes1 as shown in
Table 11-8.

PARes1[x]

PARes0[x]

PAReset[x]

0 0 0
0 1

PA[x]

1 0

not(PA[x])

1 1 1

Table 11-8: Selection bits for reset signal

A reset from Port A can be inhibited by placing a 0 on both PARes1[x] and PARes0[x] for at least 1
pin. Setting both PARes1[x] and PARes0[x] to 1, makes the reset independent of the value on the
corresponding pin. Setting both registers to hFF, will reset the circuit independent from the Port A
input value. This makes it possible to do a software reset.

Note: depending of the value of PA[0] to PA[7], the change of RegPARes0 and RegPARes1 can
cause a reset. Therefore it is safe to have always one (RegPARes0[x], RegPARes1[x]) equal to `00'
during the setting operations.

Port A as a RC enable:
PA[0] can be used to enable the RC oscillator. When RCOnPA0 bit in RegSysMisc is set to 1 and the
value of PA[0] (debounced or not) is equal to 1, the EnRc bit in RegSysClock is automatically set to
1.

11.6 Port A electrical specification

Sym

description

min

typ

max

unit Comments

INH

Input high voltage

0.7*VBAT

VBAT

2.4V

INL

Input low voltage

VSS

0.2*VBAT

VBAT

2.4V

Pull-up resistance

Cin

Input capacitance

3.5

Note 1

Note 1: this value is indicative only since it depends on the package.

Table 11-9. Port A electrical specification.

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12.1 Features

· Input / output / analog port, 8 bits wide
· Each bit can be set individually for input or output
· Each bit can be set individually for open-drain or push-pull
· Each bit can be set individually for pull-up or not (for input or open-drain mode)
· In open-drain mode, pull-up is not active when corresponding pad is set to zero
· The 8 pads can be connected by pairs to four internal analog lines (4 line analog bus)
· Two internal freq. (cpuck and 32 kHz) can be output on PB[2] and PB[3]

Product dependant:
· Two PWM signal can be output on pads PB[0] and PB[1]
· The synchronous serial interface (USRT) uses pads PB[5], PB[4]
· The UART interface uses pads PB[6] and PB[7] for Tx and Rx

12.2 Overview

Port B is a multi-purpose 8 bit Input/output port. In addition to digital functions, all pins can be used for
analog signals. All port terminals can be selected by pairs as digital input or output or as analog to
share one of four possible analog lines.

12.3 Register map

Pos.

RegPBOut

reset

description in digital mode

description in analog mode

7 0

PBOut[7-0]

r w

0 resetpconf

Pad PB[7-0] output value

Analog bus selection for pad PB[7-0]

Table 12-1: RegPBOut

Pos.

RegPBIn

reset

description in digital mode

description in analog mode

7 0

PBIn[7-0]

r w

Pad PB[7-0] input status

Unused

Table 12-2: RegPBIn

Pos.

RegPBDir

reset

description in digital mode

description in analog mode

7 0

PBDir [7-0]

r w

0 resetpconf

Pad PB[7-0] direction (0=input)

Analog bus selection for pad PB[7-0]

Table 12-3: RegPBDir

Pos.

RegPBOpen

reset

description in digital mode

description in analog mode

7 0

PBOpen[7-0]

r w

0 resetpconf

Pad PB[7-0] open drain (1 = open
drain)

Unused

Table 12-4: RegPBOpen

Pos.

RegPBPullup

reset

description in digital mode

description in analog mode

7 0

PBPullup[7]

r w

0 resetpconf

Pull-up for pad PB[7-0] (1=active)

Connect pad PB[7-0] on selected ana
bus

Table 12-5: RegPBPullup

Pos.

RegPBAna

reset

description in digital mode

description in analog mode

7 4

0000

Unused

PBAna [3]

r w

0 resetpconf

Set PB[7:6] in analog mode

PBAna [2]

r w

0 resetpconf

Set PB[5:4] in analog mode

PBAna [1]

r w

0 resetpconf

Set PB[3:2] in analog mode

PBAna [0]

r w

0 resetpconf

Set PB[1:0] in analog mode

Table 12-6: RegPBAna

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Note: Depending on the status of the EnResPConf bit in RegSysCtrl, the reset conditions of the
registers are different. See the reset block documentation for more details on the resetpconf signal.

12.4 Port B capabilities

Port B

usage (priority)

name

analog

(high)

functions
(medium)

digital

(low) (default)

PB[7] uart

I/O

PB[6]

analog

uart Tx

I/O

PB[5] usrt

I/O

PB[4]

analog

usrt S0

I/O

PB[3] 32

kHz

I/O

PB[2]

analog

clock CPU

I/O

PB[1]

PWM1 Counter C (C+D)

I/O

PB[0]

analog

PWM0 Counter A (A+B)

I/O

Table 12-7: Different Port B functionality

Table 12-7 shows the different usage that can be made of the port B with the order of priority. If a pair
of pins is selected to be analog, it overwrites the function and digital set-up. If the pin is not selected
as analog, but a function is enabled, it overwrites the digital set-up. If neither the analog nor function
are selected for a pin, it is used as an ordinary digital I/O. This is the default configuration at start-up.

12.5 Port B analog capability

12.5.1

Port B analog configuration

Port B terminals can be attached to a 4 line analog bus by setting the PBAna[x] bits to 1 in the
RegPBAna register.

The other registers then define the connection of these 4 analog lines to the different pads of Port B.
This can be used to implement a simple LCD driver or A/D converter. Analog switching is available
only when the circuit is powered with sufficient voltage (see specification below). Below the specified
supply voltage, only voltages that are close to VSS or VBAT can be switched.

When PBAna[x] is set to 1, a pair of Port B terminals is switched from digital I/O mode to analog
mode. The usage of the registers RegPBPullup, RegPBOut and RegPBDir define the analog
configuration (see Table 12-8).

When PBAna[x] = 1, then PBPullup[x] connects the pin to the analog bus. PBDir[x] and PBPOut[x]
select which of the 4 analog lines is used. For odd values of x, the selection bits are in the register
RegPBOut (see Table 12-8). For even values of x, the selection bits are in the register RegPBDir
(see Table 12-9).

if x is odd, PBOut[x, x-1]

PBPullup[x]

PB[x] selection on

analog line 0

analog line 1

analog line 2

analog line 3

XX 0

High

impedance

Table 12-8: Selection of the analog lines for PB[x] when x is odd and PBAna[x] = 1

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if x is even, PBDir[x+1, x]

PBPullup[x]

PB[x] selection on

analog line 0

analog line 1

analog line 2

analog line 3

XX 0

High

impedance

Table 12-9: Selection of the analog lines for PB[x] when x is even and PBAna[x] = 1

Example:

Set the pads PB[2] and PB[3] on the analog line 3. (the values X depend on the configuration
of others pads)
-

apply high impedance in the analog mode (move RegPBPullup,#0bXXXX00XX)

go to analog mode (move RegPBAna,#0bXXXXXX1X)

select the analog line3 (move RegPBDir,#0bXXXX11XX and move
RegPBOut,#0bXXXX11XX)

connect the analog line to the pins (move RegPBPullup,#0bXXXX11XX)

12.5.2

Port B analog function specification

The table below defines the on-resistance of the switches between the pin and the analog bus for
different conditions. The series resistance between 2 pins of Port B connected to the same analog
line is twice the resistance given in the table.

sym

description

min

typ

max

unit

Comments

Ron

switch resistance

Note 1

Ron switch

resistance

Note 2

Cin

input capacitance (off)

3.5

Note 3

Cin

input capacitance (on)

4.5

Note 4

Table 12-10. Analog input specifications.

Note 1: This is the series resistance between the pad and the analog line in 2 cases
1.

VBAT

2.4V and the VMULT peripheral is present on the circuit and enabled.

VBAT

3.0V and the VMULT peripheral is not present on the circuit.

Note 2: This is the series resistance in case VBAT

2.8V and the peripheral VMULT is not present

on the circuit.
Note 3: This is the input capacitance seen on the pin when the pin is not connected to an analog line.
This value is indicative only since it is product and package dependent.
Note 4: This is the input capacitance seen on the pin when the pin is connected to an analog line and
no other pin is connected to the same analog line. This value is indicative only since it is product and
package dependent.

12.6 Port B function capability

The Port B can be used for different functions implemented by other peripherals. The description
below is applicable only in so far the circuit contains these peripherals.

When the counters are used to implement a PWM function (see the documentation of the counters),
the PB[0] and PB[1] terminals are used as outputs (PB[0] is used if CntPWM0 in RegCntConfig1 is
set to 1, PB[1] is used if CntPWM1 in RegCntConfig1 is set to 1) and the PWM generated values
overwrite the values written in RegPBout. However, PBDir(0) and PBDir(1) are not automatically
overwritten and have to be set to 1.

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If OutputCkXtal is set in RegSysMisc, the Xtal clock is output on PB[3] (EnableXtal in RegSysClock
must be set to 1). This overrides the value contained in PBOut(3). However, PBDir(3) must be set to
1. The duty cycle of the clock signal is about 50%.

Similarly, if OutputCkCpu is set in RegSysMisc, the CPU frequency is output on PB[2]. This
overrides the value contained in PBOut(2). However, PBDir(2) must be set to 1.

The frequency of the CPU clock depends on the selection of the CpuSel bit in the RegSysClock
register (see clock_gen_ff).

Pins PB[5] and PB[4] can be used for S1 and S0 of the USRT (see USRT documentation) when the
UsrtEnable bit is set in RegUsrtCtrl. The PB[5] and PB[4] then become open-drain. This overrides
the values contained in PBOpen(5:4), PBOut(5:4) and PBDir(5:4). If there is no external pull-up
resistor on these pins, internal pull-ups should be selected by setting PBPullup(5:4). When S0 is an
output, the pin PB[4] takes the value of UsrtS0 in RegUrstS0. When S1 is an output, the pin PB[5]
takes the value of UsrtS1 in RegUrstS1.

Pins PB[6] and PB[7] can be used by the UART (see UART documentation). When UartEnTx in
RegUartCtrl is set to 1, PB[6] is used as output signal Tx. When UartEnRx in RegUartCtrl is set to 1,
PB[7] is used as input signal Rx. This overrides the values contained in PBOut(7:6) and PBDir(7:6).

12.7 Port B digital capabilities

12.7.1

Port B digital configuration

The direction of each bit within Port B (input only or input/output) can be individually set using the
RegPBDir register. If PBDir[x] = 1, both the input and output buffer are active on the corresponding
Port B. If PBDir[x] = 0, the corresponding Port B pin is an input only and the output buffer is in high
impedance. After reset (resetpconf) Port B is in input only mode (PBDir[x] are reset to 0).

The input values of Port B are available in RegPBIn (read only). Reading is always direct - there is no
debounce function in Port B. In case of possible noise on input signals, a software debouncer with
polling or an external hardware filter have to be realized. The input buffer is also active when the port
is defined as output and allows to read back the effective value on the pin.

Data stored in RegPBOut are output at Port B if PBDir[x] is 1. The default value after reset is low (0).

When a pin is in output mode (PBDir[x] is set to 1), the output can be a conventional CMOS (Push-
Pull) or a N-channel Open-drain, driving the output only low. By default, after reset (resetpconf) the
PBOpen[x] in RegPBOpen is cleared to 0 (push-pull). If PBOpen[x] in RegPBOpen is set to 1 then
the internal P transistor in the output buffer is electrically removed and the output can only be driven
low (PBOut[x]=0). When PBOut[x]=1, the pin is high Impedance. The internal pull-up or an external
pull-up resistor can be used to drive the pin high.
Note: Because the P transistor actually exists (this is not a real Open-drain output) the pull-up range

is limited to VDD + 0.2V (avoid forward bias the P transistor / diode).

Each bit can be set individually for pull-up or not using register RegPBPullup. Input is pulled up when
its corresponding bit in this register is set to 1. Default status after (resetpconf) is 0, which means
without pull up. To limit power consumption, pull-up resistors are only enabled when the associated
pin is either a digital input or an N-channel open-drain output with the pad set to 1. In the other cases
(push-pull output or open-drain output driven low), the pull up resistors are disabled independent of
the value in RegPBPullup.

After power-on reset, the Port B is configured as an input port without pull-up.

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13.1 Features

Input / output port, 8 bits wide

Each bit can be set individually for input or output

13.2 Overview

Port C (PC) is a general purpose 8 bit input/output digital port.
Figure 13-1 shows its structure.

Figure 13-1: structure of Port C

13.3 Port C (PC) Operation

The direction of each bit within Port C (input or output) can be individually set by using the RegPCDir
register. If PCDir[x] = 1, the corresponding Port C pin becomes an output. After reset, Port C is in
input mode (PCDir[x] are reset to 0).

Output mode:
Data is stored in RegPCOut prior to output at Port C.

Input mode:
The status of Port C is available in RegPCIn (read only). Reading is always direct - there is no digital
debounce function associated with Port C. In case of possible noise on input signals, a software
debouncer or an external filter must be realized.

By default after reset, Port C is configured as an input port.

13.4 Register map

There are three registers in the Port C (PC), namely RegPCIn, RegPCOut and RegPCDir. Table
13-1 to Table 13-3 show the mapping of control bits and functionality of these registers.

Pos.

RegPCIn

Reset

Description

7-0

PCIn

pad PC input value

Table 13-1. RegPCIn

RegPCIn

RegPCOut

RegPCDir

Port C

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14.1 Features

Full duplex operation with buffered receiver and transmitter.

Internal baud rate generator with 12 programmable baud rates (300 - 115200).

7 or 8 bits word length.

Even, odd, or no-parity bit generation and detection

1 stop bit

Error receive detection: Start, Parity, Frame and Overrun

Receiver echo mode

2 interrupts (receive full and transmit empty)

Enable receive and/or transmit

Invert pad Rx and/or Tx

14.2 Overview

The UART pins are PB[7], which is used as Rx - receive and PB[6] as Tx - transmit.

14.3 Registers

map

pos.

RegUartCmd

Reset

Description

SelXtal

0 resetsystem

Select input clock: 0 = RC/external, 1 = xtal

UartEnRx2

0 resetsystem

Enable Uart Reception

5-3

UartRcSel(2:0)

000 resetsystem

RC prescaler selection

UartPM

0 resetsystem

Select parity mode: 0 = odd, 1 = even

UartPE

0 resetsystem

Enable parity: 1 = with parity, 0 = no parity

UartWL

1 resetsystem

Select word length: 1 = 8 bits, 0 = 7 bits

Table 14-1: RegUartCmd

Pos.

RegUartCtrl

reset

Description

UartEcho

0 resetsystem

Enable echo mode:

1 = echo Rx->Tx, 0 = no echo

UartEnRx1

0 resetsystem

Enable uart reception

UartEnTx

0 resetsystem

Enable uart transmission

UartXRx

0 resetsystem

Invert pad Rx

UartXTx

0 resetsystem

Invert pad Tx

2-0

UartBR(2:0)

101 resetsystem

Select baud rate

Table 14-2: RegUartCtrl

pos.

RegUartTx

reset

Description

7-0 UartTx rw 00000000

resetsystem

Data to be sent

Table 14-3: RegUartTx

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XE88LC05/05A

pos.

RegUartTxSta

reset

description

7-2 - r 000000

Unused

UartTxBusy

0 resetsystem

Uart busy transmitting

0 UartTxFull r 0

resetsystem

RegUartTx full

Set by writing to RegUartTx

Cleared when transferring RegUartTx into

internal shift register

Table 14-4: RegUartTxSta

pos.

RegUartRx

reset

description

7-0 UartRx r 00000000

resetsystem

Received data

Table 14-5: RegUartRx

pos.

RegUartRxSta

Reset

description

7-6 - r 00

Unused

UartRxSErr

0 resetsystem

Start error

UartRxPErr

0 resetsystem

Parity error

UartRxFErr

0 resetsystem

Frame error

UartRxOErr

0 resetsystem

Overrun error

Cleared by writing RegUartRxSta

UartRxBusy

0 resetsystem

Uart busy receiving

0 UartRxFull r 0

resetsystem

RegUartRx full

Cleared by reading RegUartRx

Table 14-6: RegUartRxSta

14.4 Interrupts

map

interrupt source

default mapping in the interrupt manager

Irq_uart_Tx

IrqHig(1)

Irq_uart_Rx

IrqHig(0)

Table 14-7: Interrupts map

14.5 Uart baud rate selection

In order to have correct baud rates, the Uart interface has to be fed with a stable and trimmed clock
source. The clock source can be the RC oscillator or the crystal oscillator. The precision of the baud
rate will depend on the precision of the selected clock source.

14.5.1

Uart on the RC oscillator

To select the RC oscillator for the Uart, the bit SelXtal in RegUartCmd has to be 0.

In order to obtain a correct baud rate, the RC oscillator frequency has to be set to one of the
frequencies given in the table on the next page. The precision of the obtained baud rate is directly
proportional to the frequency deviation with respect to the values in the table.

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XE88LC05/05A

Frequency selection for correct Uart

baud rate with RC oscillator (Hz)

2'457'600
1'843'200
1'228'800

614'400

For each of these frequencies, the baud rate can be selected with the bits UartBR(2:0) in
RegUartCtrl and UartRcSel(2:0) in RegUartCmd as shown in Table 14-8

RC frequency (Hz)

2'457'600

1'228'800

614'400

1'843'200

UartRcSel

010

001

000

111 38400

115200

110 19200

57600

101 9600

28800

UartBR

100 Not

possible

4800

14400

Table 14-8: Uart baud rate with RC clock

Note: The precision of the baud rate is directly proportional to the frequency deviation of the used
clock from the ideal frequency given in the table. In order to increase the precision and stability of the
RC oscillator, the DFLL (digital frequency locked loop) can be used with the crystal oscillator as a
reference.

14.5.2

Uart on the crystal oscillator

In order to use the crystal oscillator as the clock source for the Uart, the bit SelXtal in RegUartCmd
has to be set. The crystal oscillator has to be enabled by setting the EnableXtal bit in RegSysClock.
The baud rate selection is done using the UartBR and UartRcSel bits as shown in Table 14-9.

Xtal freq. (Hz)

UartRcSel

UartBR

Baud rate

011 2400
010 1200
001 600

32768 001

000 300

Table 14-9: Uart baud rate with Xtal clock

Due to the odd ratio between the crystal oscillator frequency and the baud rate, the generated baud
rate has a systematic error of 2.48%.

14.6 Function

description

14.6.1 Configuration

bits

The configuration bits of the Uart serial interface can be found in the registers RegUartCmd and
RegUartCtrl.

The bit SelXtal is used to select the clock source (see chapter 14.5). The bits UartSelRc and UartBR
select the baud rate (see chapter 14.5).

The bits UartEnTx is used to enable or disable the transmission.

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XE88LC05/05A

The bits UartEnRx1 and UartEnRx2 are used to enable or disable the reception. When one is set to
1, the reception is enabled.

The word length (7 or 8 data bits) can be chosen with UartWL. A parity bit is added during
transmission or checked during reception if UartPE is set. The parity mode (odd or even) can be
chosen with UartPM.

Setting the bits UartXRx and UartXTx inverts the Rx respectively Tx signals.

The bit UartEcho is used to send the received data automatically back. The transmission function
becomes then: Tx = Rx XOR UartXTx.

14.6.2 Transmission

In order to send data, the transmitter has to be enabled by setting the bit UartEnTx. Data to be sent
has to be written to the register RegUartTx. The bit UartTxFull in RegUartTxSta then goes to 1,
indicating to the transmitter that a new word is available. As soon as the transmitter has finished
sending the previous word, it then loads the contents of the register RegUartTx to an internal shift
register and clears the UartTxFull bit. An interrupt is generated on Irq_uart_Tx at the falling edge of
the UartTxFull bit. The bit UartTxBusy in RegUartTxSta shows that the transmitter is busy
transmitting a word.

A timing diagram is shown in Figure 14-1. Data are first sent LSB.

New data should be written to the register RegUartTx only while UartTxFull is 0, otherwise data will
be lost.

Asynchronous Transmission

write to RegUartTx

RegUartTx

word 1

reguarttx_shift

word 1

shift clock

start

b6/7

parity

stop

UartTxBusy

UartTxFull

Irq_uart_Tx

Asynchronous Transmission (back to back)

word 1

word 2

write to RegUartTx

RegUartTx

word 1

word 2

reguarttx_shift

word 1

word 2

shift clock

start

b6/7

stop

start

UartTxBusy

UartTxFull

Irq_uart_Tx

Figure 14-1. Uart transmission timing diagram.

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14.6.3 Reception

On detection of the start bit, the UartRxBusy bit is set. On detection of the stop bit, the received data
are transferred from the internal shift register to the register RegUartRx. At the same time, the
UartRxFull bit is set and an interrupt is generated on Irq_uart_Rx. This indicates that new data is
available in RegUartRx. The timing diagram is shown in Figure 14-2.

The UartRxFull bit is cleared when RegUartRx is read. If the register was not read before the
receiver transfers a new word to it, the bit UartRxOErr (overflow error) is set and the previous
contents of the register is lost. UartRxOErr is cleared by writing any data to RegUartRxSta.

The bit UartRxSErr is set if a start error has been detected. The bit is updated at data transfer to
RegUartRx.

The bit UartRxPErr is set if a parity error has been detected, i.e. the received parity bit is not equal to
the calculated parity of the received data. The bit is updated at data transfer to RegUartRx.

The bit UartRxFErr in RegUartRxSta shows that a frame error has been detected. No stop bit has
been detected.

Asynchronous Reception

read of RegUartRx (software)

reguartrx_shift

word 1

RegUartRx

word 1

shift clock

start

b6/7

parity

stop

UartRxBusy

UartRxFull

Irq_uart_Rx

Figure 14-2. Uart reception timing diagram.

14.7 Interrupt or polling

The transmission and reception software can be driven by interruption or by polling the status bits.

Interrupt driven reception: each time an Irq_uart_Rx interrupt is generated, a new word is available in
RegUartRx. The register has to be read before a new word is received.
Interrupt driven transmission: each time the contents of RegUartTx is transferred to the transmission
shift register, an Irq_uart_Tx interrupt is generated. A new word can then be written to RegUartTx.

Reception driven by polling: the UartRxFull bit is to be read and checked. When it is 1, the
RegUartRx register contains new data and has to be read before a new word is received.
Transmission driven by polling: the UartTxFull bit is to read and checked. When it is 0, the
RegUartTx register is empty and a new word can be written to it.

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14.8 Software

hints

Example of program for a transmission with polling:

1. The RegUartCmd register and the RegUartCtrl register are initialized (for example: 8 bit word

length, odd parity, 9600 baud, enable Uart transmission).

2. Write a byte to RegUartTx.
3. Wait until the UartTxFull bit in RegUartTxSta register equals 0.
4. Jump to 2 to write the next byte if the message is not finished.
5. End of transmission.

Example of program for a transmission with interrupt:

1. The RegUartCmd register and the RegUartCtrl register are initialized (for example: 8 bit word

length, odd parity, 9600 baud, enable Uart transmission).

2. Write a byte to RegUartTx.
3. After an interrupt and if the message is not finished, jump to 2
4. End of transmission.

Example of program for a reception with polling:

1. The

RegUartCmd register and the RegUartCtrl register are initialized (for example: 8 bit word

length, odd parity, 9600 baud, enable Uart reception).

2. Wait until the UartRxFull bit in the RegUartRxSta register equals 1.
3. Read the RegUartRxSta and check if there is no error.
4. Read data in RegUartRx.
5. If data is not equal to End-Of-Line, then jump to 2.
6. End of reception.

Example of program for a reception with interrupt:

1. The RegUartCmd register and the RegUartCtrl register are initialized (for example: 8 bit word

length, odd parity, 9600 baud, enable Uart reception).

2. When there is an interrupt, jump to 3
3. Read RegUartRxSta and check if there is no error.
4. Read data in RegUartRx.
5. If data is not equal to End-Of-Line, then jump to 2.
6. End of reception.

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15.1 Features

The USRT implements a hardware support for software implemented serial protocols:

Control of two external lines S0 and S1 (read/write).

Conditional edge detection generates interrupts.

S0 rising edge detection.

S1 value is stored on S0 rising edge.

S0 signal can be forced to 0 after a falling edge on S0 for clock stretching in the low state.

S0 signal can be stretched in the low state after a falling edge on S0 and after a S1 conditional

detection.

15.2 Overview

The USRT block supports software universal synchronous receiver and transmitter mode interfaces.

External lines S0 and S1 respectively correspond to clock line and data line. S0 is mapped to PB[4]
and S1 to PB[5] when the USRT block is enabled. It is independent from RegPBdir (Port B can be
input or output). When USRT is enabled, the configurations in port B for PB[4] and PB[5] are
overwritten by the USRT configuration. Internal pull-ups can be used by setting the PBPullup[5:4]
bits.

Conditional edge detections are provided.

RegUsrtS1 can be used to read the S1 data line from PB[5] in receive mode or to drive the output S1
line PB[5] by writing it when in transmit mode. It is advised to read S1 data when in receive mode from
the RegUsrtBufferS1 register, which is the S1 value sampled on a rising edge of S0.

15.3 Register map

Block configuration registers:

pos.

RegUsrtS1

reset

function

7-1 -

r 0000000

Unused

UsrtS1

1 resetsystem

Write: data S1 written to pad PB[5]),
Read: value on PB[5] (not UsrtS1 value).

Table 15-1: RegUsrtS1

pos.

RegUsrtS0

Reset

function

7-1 -

r 0000000

Unused

UsrtS0

1 resetsystem

Write: clock S0 written to pad PB[4],
Read: value on PB[4] (not UsrtS0 value).

Table 15-2: RegUsrtS0

The values that are read in the registers RegUsrtS1 and RegUsrtS0 are not necessarily the same as
the values that were written in the register. The read value is read back on the circuit pins, not in the
registers. Since the outputs are open drain, a value different from the register value may be forced by
an external circuit on the circuit pins.

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Condition 2 is satisfied when S0=1 at the rising edge of S1. The bit UsrtCond2 in RegUsrtCond2 is
set when the condition 2 is detected and the USRT interface is enabled. Condition 2 is asserted for
both modes (receiver and transmitter). The UsrtCond2 bit is read only and is cleared by all reset
conditions and by writing any data to its address.

Condition 2 occurrence also generates an interrupt on Irq_cond2.

15.7 Interrupts or polling

In receive mode, there are two possibilities for detecting condition 1 or 2: the detection of the condition
can generate an interrupt or the registers can be polled (reading and checking the RegUsrtCond1
and RegUsrtCond2 registers for the status of USRT communication).

15.8 Function description

The bit UsrtEnable in RegUsrtCtrl is used to enable the USRT interface and controls the PB[4] and
PB[5] pins. This bit puts these two port B lines in the open drain configuration requested to use the
USRT interface.

If no external pull-ups are added on PB[4] and PB[5], the user can activate internal pull-ups by setting
PBPullup[4] and PBPullup[5] in RegPBPullup.

The bits UsrtEnWaitS0, UsrtEnWaitCond1, UsrtWaitS0 in RegUsrtCtrl are used for
transmitter/receiver control of USRT interface.

Figure 15-3 shows the unconditional clock stretching function which is enabled by setting
UsrtEnWaitS0.

UsrtWaitS0

write Reg UsrtBufferS1

Figure 15-3: S0 Stretching (UsrtEnWaitS0=1)

When UsrtEnWaitS0 is 1, the S0 line will be maintained at 0 after its falling edge (clock stretching).
UsrtWaitS0 is then set to 1, indicating that the S0 line is forced low. One can release S0 by writing to
the RegUsrtBufferS1 register.

The same can be done in combination with condition 1 detection by setting the UsrtEnWaitCond1 bit.
Figure 15-4 shows the conditional clock stretching function which is enabled by setting
UsrtEnWaitCond1.

16-1

Acquisition chain 2.5 30 Avril 2002

D0304-40

Datasheet
XE88LC05/05A

16. Acquisition

chain

16.1 ZoomingADC

Features............................................................................................... 16-2

16.2 Overview ......................................................................................................................... 16-2

16.3 Register

map .................................................................................................................. 16-2

16.4 ZoomingADC

Description .......................................................................................... 16-4

16.4.1 Acquisition Chain ............................................................................................................. 16-4
16.4.2 Peripheral Registers ........................................................................................................ 16-6
16.4.3 Continuous-Time vs. On-Request ................................................................................... 16-8

16.5 Input

Multiplexers .......................................................................................................... 16-9

16.6 Programmable

Gain Amplifiers .................................................................................. 16-10

16.6.1 PGA & ADC Enabling .................................................................................................... 16-12
16.6.2 PGA1 ............................................................................................................................. 16-12
16.6.3 PGA2 ............................................................................................................................. 16-12
16.6.4 PGA3 ............................................................................................................................. 16-12

16.7 ADC

Characteristics .................................................................................................... 16-13

16.7.1 Conversion Sequence ................................................................................................... 16-13
16.7.2 Sampling Frequency...................................................................................................... 16-14
16.7.3 Over-Sampling Ratio ..................................................................................................... 16-14
16.7.4 Elementary

Conversions................................................................................................ 16-14

16.7.5 Resolution ...................................................................................................................... 16-15
16.7.6 Conversion

Time & Throughput..................................................................................... 16-16

16.7.7 Output

Code Format ...................................................................................................... 16-16

16.7.8 Power

Saving Modes..................................................................................................... 16-18

16.8 Specifications

and

Measured Curves........................................................................ 16-18

16.8.1 Default Settings ............................................................................................................. 16-19
16.8.2 Specifications................................................................................................................. 16-20
16.8.3 Linearity ......................................................................................................................... 16-22
16.8.3.1 Integral non-linearity ...................................................................................................... 16-22
16.8.3.2 Differential non-linearity ................................................................................................. 16-25
16.8.4 Noise.............................................................................................................................. 16-26
16.8.5 Gain Error and Offset Error............................................................................................ 16-27
16.8.6 Power

Consumption ...................................................................................................... 16-28

16.8.7 Power Supply Rejection Ratio ....................................................................................... 16-30

16.9 Application Hints ......................................................................................................... 16-31
16.9.1 Input

Impedance ............................................................................................................ 16-31

16.9.2 PGA Settling or Input Channel Modifications ................................................................ 16-31
16.9.3 PGA Gain & Offset, Linearity and Noise........................................................................ 16-31
16.9.4 Frequency

Response..................................................................................................... 16-32

16.9.5 Power

Reduction ........................................................................................................... 16-33

16-2

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Datasheet
XE88LC05/05A

16.1 ZoomingADC

Features

The ZoomingADC

is a complete and versatile low-power analog front-end interface typically

intended for sensing applications. The key features of the ZoomingADC

are:

Programmable 6 to 16-bit dynamic range oversampled ADC

Flexible gain programming between 0.5 and 1000

Flexible and large range offset compensation

4-channel differential or 8-channel single-ended input multiplexer

2-channel differential reference inputs

Power saving modes

Direct interfacing to CoolRisc

microcontroller

16.2 Overview

PGA1

PGA2

PGA3

ADC

GD1

GD2

GD3

OFF2

OFF3

0
1
2
3
4
5
6
7

0
1
2
3

Analog

Inputs

REF

IN,ADC

Gain1 Gain2

Gain3

Offset3

Offset2

Reference

Selection

Input

Selection

ZOOM

Reference

Inputs

Figure 16-1. ZoomingADC

general functional block diagram

The total acquisition chain consists of an input multiplexer, 3 programmable gain amplifier stages and
an oversampled A/D converter. The reference voltage can be selected on two different channels. Two
offset compensation amplifiers allow for a wide offset compensation range. The programmable gain
and offset allow one to zoom in on a small portion of the reference voltage defined input range.

16.3 Register

map

There are eight registers in the acquisition chain (AC), namely RegAcOutLsb, RegAcOutMsb,
RegAcCfg0, RegAcCfg1, RegAcCfg2, RegAcCfg3, RegAcCfg4 and RegAcCfg5. Table 16-2 to
Table 16-9 show the mapping of control bits and functionality of these registers while Table 16-1 gives
an overview of these eight.

16-3

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Datasheet
XE88LC05/05A

The register map only gives a short description of the different configuration bits. More detailed
information is found in subsequent sections.

register name
RegAcOutLsb
RegAcOutMsb
RegAcCfg0
RegAcCfg1
RegAcCfg2
RegAcCfg3
RegAcCfg4
RegAcCfg5

Table 16-1: AC registers

pos.

RegAcOutLsb

reset

description

7:0 Out[7:0]

00000000

resetsystem

LSB of the output code

Table 16-2: RegAcOutLsb

pos.

RegAcOutMsb

reset

description

7:0 Out[15:8]

00000000

resetsystem

MSB of the output code

Table 16-3: RegAcOutMsb

pos.

RegAcCfg0

reset

description

Start

w r0 0 resetsystem

starts a conversion

6:5

SET_NELCONV[1:0]

r w

01 resetsystem

sets the number of elementary conversions

4:2 SET_OSR[2:0]

010

resetsystem

sets the oversampling rate of an elementary

conversion

CONT

r w

0 resetsystem

continuous conversion mode

0 reserved

resetsystem

Table 16-4: RegAcCfg0

pos.

RegAcCfg1

reset

description

7:6 IB_AMP_ADC[1:0]

resetsystem Bias current selection of the ADC converter

5:4 IB_AMP_PGA[1:0]

resetsystem

Bias current selection of the PGA stages

3:0 ENABLE[3:0]

0000
resetsystem

Enables the different PGA stages and the ADC

Table 16-5: RegAcCfg1

pos.

RegAcCfg2

reset

description

7:6 FIN[1:0]

resetsystem

Sampling frequency selection

5:4 PGA2_GAIN[1:0]

resetsystem

PGA2 stage gain selection

3:0 PGA2_OFFSET[3:0]

0000
resetsystem

PGA2 stage offset selection

Table 16-6: RegAcCfg2

16-4

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Datasheet
XE88LC05/05A

pos.

RegAcCfg3

reset

description

7 PGA1_GAIN

resetsystem

PGA1 stage gain selection

6:0 PGA3_GAIN[6:0] r

0000000
resetsystem

PGA3 stage gain selection

Table 16-7: RegAcCfg3

pos.

RegAcCfg4

reset

description

7 reserved

Unused

6:0 PGA3_OFFSET[6:0]

w 0000000

resetsystem

PGA3 stage offset selection

Table 16-8: RegAcCfg4

pos.

RegAcCfg5

reset

description

BUSY

0 resetsystem

Activity flag

DEF

w r0 0

Selects default configuration

5:1 AMUX[4:0]

00000
resetsystem

Input channel configuration selector

VMUX

r w

0 resetsystem

Reference channel selector

Table 16-9: RegAcCfg5

16.4 ZoomingADC

Description

Figure 16-2 gives a more detailed description of the acquisition chain.

16.4.1 Acquisition

Chain

Figure 16-1 shows the general block diagram of the acquisition chain (AC). A control block (not shown
in Figure 16-1) manages all communications with the CoolRisc

microcontroller.

Analog inputs can be selected among eight input channels, while reference input is selected between
two differential channels.

The core of the zooming section is made of three differential programmable amplifiers (PGA). After
selection of a combination of input and reference signals V

and V

REF

, the input voltage is modulated

and amplified through stages 1 to 3. Fine gain programming up to 1'000V/V is possible. In addition,
the last two stages provide programmable offset. Each amplifier can be bypassed if needed.

The output of the PGA stages is directly fed to the analog-to-digital converter (ADC), which converts
the signal V

IN,ADC

into digital.

Like most ADCs intended for instrumentation or sensing applications, the ZoomingADC

is an over-

sampled converter (See Note

). The ADC is a so-called incremental converter, with bipolar operation

(the ADC accepts both positive and negative input voltages). In first approximation, the ADC output
result relative to full-scale (FS) delivers the quantity:

Note: Over-sampled converters are operated with a sampling frequency f

much higher than the input signal's Nyquist rate

(typically f

is 20-1'000 times the input signal bandwidth). The sampling frequency to throughput ratio is large (typically 10-500).

These converters include digital decimation filtering. They are mainly used for high resolution, and/or low-to-medium speed
applications.

16-6

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Datasheet
XE88LC05/05A

16.4.2 Peripheral

Registers

Figure 16-2 shows a detailed functional diagram of the ZoomingADC

In table 16-10 the configuration of the peripheral registers is detailed. The system has a bank of eight
8-bit registers: six registers are used to configure the acquisition chain (

RegAcCfg0 to 5

), and two

registers are used to store the output code of the analog-to-digital conversion (

RegAcOutMsb

Lsb

). The register coding of the ADC parameters and performance characteristics are detailed in

Section 16.7.

Table 16-10. Peripheral registers to configure the acquisition chain (AC)

and to store the analog-to-digital conversion (ADC) result

Bit Position

Register

Name

7 6 5 4 3 2 1 0

RegAcOutLsb

OUT[7:0]

RegAcOutMsb

OUT[15:8]

RegAcCfg0

Default values:

START

SET_NELC[1:0]

SET_OSR[2:0]

010

CONT

TEST

RegAcCfg1

Default values:

IB_AMP_ADC[1:0]

IB_AMP_PGA[1:0]

ENABLE[3:0]

0001

RegAcCfg2

Default values:

FIN[1:0]

PGA2_GAIN[1:0]

PGA2_OFFSET[3:0]

0000

RegAcCfg3

Default values:

PGA1_G

PGA3_GAIN[6:0]

0000000

RegAcCfg4

Default values:

PGA3_OFFSET[6:0]

0000000

RegAcCfg5

Default values:

BUSY

DEF

AMUX[4:0]

00000

VMUX

With:

OUT

: (r) digital output code of the analog-to-digital converter. (MSB =

OUT[15]

)

START

: (w) setting this bit triggers a single conversion (after the current one is finished). This bit always

reads back 0.

SET_NELC

: (rw) sets the number of elementary conversions to 2

SET_NELC[1:0]

. To compensate for offsets,

the input signal is chopped between elementary conversions (1,2,4,8).

SET_OSR

: (rw) sets the over-sampling rate (OSR) of an elementary conversion to 2

(3+SET_OSR[2:0])

. OSR = 8,

16, 32, ..., 512, 1024.

CONT

: (rw) setting this bit starts a conversion. A new conversion will automatically begin as long as the bit

remains at 1.

TEST

: bit only used for test purposes. In normal mode, this bit is forced to 0 and cannot be overwritten.

IB_AMP_ADC

: (rw) sets the bias current in the ADC to 0.25*(1+

IB_AMP_ADC[1:0]

) of the normal operation

current (25, 50, 75 or 100% of nominal current). To be used for low-power, low-speed operation.

IB_AMP_PGA

: (rw) sets the bias current in the PGAs to 0.25*(1+

IB_AMP_PGA[1:0]

) of the normal

operation current (25, 50, 75 or 100% of nominal current). To be used for low-power, low-speed operation.

ENABLE

: (rw) enables the ADC modulator (bit 0) and the different stages of the PGAs (PGAi by bit i=1,2,3).

PGA stages that are disabled are bypassed.

FIN

: (rw) These bits set the sampling frequency of the acquisition chain. Expressed as a fraction of the

oscillator frequency, the sampling frequency is given as: 00 1/4 f

, 01 1/8 f

, 10 1/32 f

, 11

~8kHz.

PGA1_GAIN

: (rw) sets the gain of the first stage: 0 1, 1 10.

PGA2_GAIN

: (rw) sets the gain of the second stage: 00 1, 01 2, 10 5, 11 10.

PGA3_GAIN

: (rw) sets the gain of the third stage to

PGA3_GAIN[6:0]

1/12.

PGA2_OFFSET

: (rw) sets the offset of the second stage between 1 and +1, with increments of 0.2. The MSB

gives the sign (0

positive, 1

negative); amplitude is coded with the bits

PGA2_OFFSET[5:0]

16-8

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Datasheet
XE88LC05/05A

16.4.3 Continuous-Time

vs.

On-Request

The ADC can be operated in two distinct modes: "continuous-time" and "on-request" modes (selected
using the bit

CONT

In "continuous-time" mode, the input signal is repeatedly converted into digital. After a conversion is
finished, a new one is automatically initiated. The new value is then written in the result register, and
the corresponding internal trigger pulse is generated. This operation is sketched in Figure 16-3. The
conversion time in this case is defined as T

CONV

Internal Trig

Ouput Code

RegACOut[15:0]

CONV

BUSY

IRQ

Figure 16-3. ADC "continuous-time" operation

Figure 16-4. ADC "on-request" operation

In the "on-request" mode, the internal behaviour of the converter is the same as in the "continuous-
time" mode, but the conversion is initiated on user request (with the

START

bit). As shown in Figure

16-4, the conversion time is also T

CONV

. Note that the flag is set at the effective start of the conversion.

Since the ADC is generally synchronized on a lower frequency clock than the CPU, there might be a
small delay (max. 1 cycle of the ADC sampling frequency) between the writing of the START or CONT
bits and the appearance of BUSY flag.

Internal Trig

Ouput Code

RegACOut[15:0]

CONV

Request

START

BUSY

IRQ

16-9

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Datasheet
XE88LC05/05A

16.5 Input

Multiplexers

The ZoomingADC

has eight analog inputs

AC_A(0)

AC_A(7)

and four reference inputs

AC_R(0)

AC_R(3)

. Let us first define the differential input voltage V

and reference voltage V

REF

respectively as:

INN

INP

(V)

(Eq. 3)

and:

REFN

REFP

REF

(V)

(Eq.

As shown in Table 16-11 the inputs can be configured in two ways: either as 4 differential channels
(V

IN1

AC_A(1)

AC_A(0)

,..., V

IN4

AC_A(7)

AC_A(6)

), or

AC_A(0)

can be used as a common

reference, providing 7 signal paths all referred to

AC_A(0)

. The control word for the analog input

selection is

AMUX[4:0]

. Notice that the bit

AMUX[3]

controls the sign of the input voltage.

AMUX[4:0]

(RegAcCfg5[5:1])

INP

INN

AMUX[4:0]

(RegAcCfg5[5:1])

INP

INN

00x00
00x01
00x10
00x11

AC_A(1)
AC_A(3)
AC_A(5)
AC_A(7)

AC_A(0)
AC_A(2)
AC_A(4)
AC_A(6)

01x00
01x01
01x10
01x11

AC_A(0)
AC_A(2)
AC_A(4)
AC_A(6)

AC_A(1)
AC_A(3)
AC_A(5)
AC_A(7)

10000
10001
10010
10011
10100
10101
10110
10111

AC_A(0)
AC_A(1)
AC_A(2)
AC_A(3)
AC_A(4)
AC_A(5)
AC_A(6)
AC_A(7)

AC_A(0)

11000
11001
11010
11011
11100
11101
11110
11111

AC_A(0)

AC_A(0)
AC_A(1)
AC_A(2)
AC_A(3)
AC_A(4)
AC_A(5)
AC_A(6)
AC_A(7)

Table 16-11. Analog input selection

Similarly, the reference voltage is chosen among two differential channels (V

REF1

AC_R(1)-

AC_R(0)

or V

REF2

AC_R(3)-AC_R(2)

) as shown in Table 16-12. The selection bit is

VMUX

. The

reference inputs V

REFP

and V

REFN

(common-mode) can be up to the power supply range.

16-12

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XE88LC05/05A

16.6.1

PGA & ADC Enabling

Depending on the application objectives, the user may enable or bypass each PGA stage. This is done
according to the word

ENABLE

and the coding given in Table 16-13. To reduce power dissipation, the

ADC can also be inactivated while idle.

16.6.2 PGA1

The first stage can have a buffer function (unity gain) or provide a gain of 10 (see Table 16-14). The
voltage V

at the output of PGA1 is:

(V)

(Eq. 5)

where GD

is the gain of PGA1 (in V/V) controlled with the bit

PGA1_GAIN

16.6.3 PGA2

The second PGA has a finer gain and offset tuning capability, as shown in Table 16-15 and Table
16-16. The voltage V

at the output of PGA2 is given by:

REF

GDoff

(V)

(Eq.

where GD

and GDoff

are respectively the gain and offset of PGA2 (in V/V). These are controlled

with the words

PGA2_GAIN[1:0]

and

PGA2_OFFSET[3:0]

As shown in equation 6, the offset correction is directly proportional to the reference voltage. All drifts
and perturbations on the reference voltage will affect the precision of the offset compensation.

16.6.4 PGA3

The finest gain and offset tuning is performed with the third and last PGA stage, according to the
coding of Table 16-17 and Table 16-18. The output of PGA3 is also the input of the ADC. Thus,
similarly to PGA2, we find that the voltage entering the ADC is given by:

REF

ADC

GDoff

(V)

(Eq.

where GD

and GDoff

are respectively the gain and offset of PGA3 (in V/V). The control words are

PGA3_GAIN[6:0]

and

PGA3_OFFSET[6:0]

. To remain within the signal compliance of the PGA

stages, the condition:

(V)

(Eq. 8)

must be verified.

As shown in equation 7, the offset correction is directly proportional to the reference voltage. All drifts
and perturbations on the reference voltage will affect the precision of the offset compensation.

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XE88LC05/05A

Finally, combining equations Eq. 5 to Eq. 7 for the three PGA stages, the input voltage V

IN,ADC

of the

ADC is related to V

by:

REF

TOT

ADC

GDoff

(V)

(Eq.

where the total PGA gain is defined as:

TOT

(V/V)

(Eq.

10)

and the total PGA offset is:

GDoff

TOT

(V/V)

(Eq.

11)

16.7 ADC

Characteristics

The main performance characteristics of the ADC (resolution, conversion time, etc.) are determined
by three programmable parameters:

sampling

frequency

over-sampling

ratio

OSR, and

number of elementary conversions N

ELCONV

The setting of these parameters and the resulting performances are described hereafter.

16.7.1 Conversion

Sequence

A conversion is started each time the bit

START

or the bit

DEF

is set. As depicted in Figure 16-5, a

complete analog-to-digital conversion sequence is made of a set of N

ELCONV

elementary incremental

conversions and a final quantization step. Each elementary conversion is made of (OSR+1) sampling
periods T

=1/f

, i.e.:

ELCONV

OSR

)

(

(s)

(Eq.

12)

The result is the mean of the elementary conversion results. An important feature is that the
elementary conversions are alternatively performed with the offset of the internal amplifiers
contributing in one direction and the other to the output code. Thus, converter internal offset is
eliminated if at least two elementary sequences are performed (i.e. if N

ELCONV

2). A few additional

clock cycles are also required to initiate and end the conversion properly.

Conversion index

Offset

ELCONV

= (OSR+1)/f

Elementary

Conversion

1
+

Elementary

Conversion

Elementary

Conversion

ELCONV

- 1

Elementary

Conversion

ELCONV

Init

End

CONV

Conversion

Result

Figure 16-5. Analog-to-digital conversion sequence

16-14

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XE88LC05/05A

16.7.2 Sampling

Frequency

The word

FIN[1:0]

is used to select the sampling frequency f

(Table 16-19). Three sub-multiples of

the internal RC-based frequency f

RCEXT

can be chosen. For

FIN

= "11", sampling frequency is about

8kHz. Additional information on oscillators and their control can be found in the clock block
documentation.

Sampling Frequency f

(Hz)

FIN[1:0]

LC01/05 LC02

1/4

1/8

RCEXT

1/8

1/16

RCEXT

1/32

1/64

RCEXT

8kHz

4kHz

Table 16-19. Sampling frequency settings (f

= RC-based frequency)

16.7.3 Over-Sampling

Ratio

The over-sampling ratio (OSR) defines the number of integration cycles per elementary conversion.
Its value is set with the word

SET_OSR[2:0]

in power of 2 steps (see Table 16-20) given by:

SET_OSR[2

OSR

(-)

(Eq.

13)

SET_OSR[2:0]

(RegAcCfg0[4:2])

Over-Sampling Ratio

OSR (-)

000 8
001 16
010 32
011 64
100 128
101 256
110 512
111 1024

Table 16-20. Over-sampling ratio settings

16.7.4 Elementary

Conversions

As mentioned previously, the whole conversion sequence is made of a set of N

ELCONV

elementary

incremental conversions. This number is set with the word

SET_NELC[1:0]

in power of 2 steps (see

Table 16-21) given by:

SET_NELC[1

ELCONV

(-)

(Eq.

14)

16-15

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XE88LC05/05A

SET_NELC[1:0]

(RegAcCfg0[6:5])

# of Elementary

Conversions

ELCONV

(-)

00 1
01 2
10 4
11 8

Table 16-21. Number of elementary conversion settings

As already mentioned, N

ELCONV

must be equal or greater than 2 to reduce internal amplifier offsets.

16.7.5 Resolution

The theoretical resolution of the ADC, without considering thermal noise, is given by:

)

(

log

)

(

log

ELCONV

OSR

(Bits)

(Eq.

15)

000

001

010

011

100

101

110

111

SET_OSR

s
o

l
u

- n

11
10
01
00

SET_NELC=

Figure 16-6. Resolution vs.

SET_OSR[2:0]

and

SET_NELC[2:0]

SET_NELC

SET_OSR

[2:0]

000 6 7 8 9
001 8 9 10

010 10 11 12 13
011 12 13 14 15
100 14 15 16 16
101 16 16

110

111

(shaded area: resolution truncated to 16 bits

due to output register size

RegAcOut[15:0]

)

Table 16-22. Resolution vs.

SET_OSR[2:0]

and

SET_NELC[1:0]

settings

Using look-up Table 16-22 or the graph plotted in Figure 16-6, resolution can be set between 6 and 16
bits. Notice that, because of 16-bit register use for the ADC output, practical resolution is limited to
16 bits, i.e. n

16. Even if the resolution is truncated to 16 bit by the output register size, it may make

sense to set OSR and N

ELCONV

to higher values in order to reduce the influence of the thermal noise in

the PGA (see section 16.8.4).

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16.7.6

Conversion Time & Throughput

As explained using Figure 16-5, conversion time is given by:

ELCONV

CONV

OSR

)

(

(s)

(Eq.

16)

and throughput is then simply 1/T

CONV

. For example, consider an over-sampling ratio of 256, 2

elementary conversions, and a sampling frequency of 500kHz (

SET_OSR

= "101",

SET_NELC

= "01",

= 2MHz, and

FIN

= "00"). In this case, using Table 16-23, the conversion time is 515 sampling

periods, or 1.03ms. This corresponds to a throughput of 971Hz in continuous-time mode. The plot of
Figure 16-7 illustrates the classic trade-off between resolution and conversion time.

SET_NELC[1:0]

SET_OSR

[2:0]

000 10 19 37 73
001 18 35 69 137
010 34 67

133

265

011 66

131

261

521

100 130

259

517

1033

101 258

515

1029

2057

110 514

1027

2053

4105

111 1026 2051 4101 8201

Table 16-23. Normalized conversion time (T

CONV

) vs.

SET_OSR[2:0]

and

SET_NELC[1:0]

(normalized to sampling period 1/f

)

4.0

6.0

8.0

10.0

12.0

14.0

16.0

10.0

100.0

1000.0

10000.0

Normalized Conversion Time - T

CONV

[-]

l
u

- n [B

i
t
s

]

SET_NELC

Figure 16-7. Resolution vs. normalized conversion time for different

SET_NELC[1:0]

16.7.7

Output Code Format

The ADC output code is a 16-bit word in two's complement format (see Table 16-24). For input
voltages outside the range, the output code is saturated to the closest full-scale value (i.e. 0x7FFF or
0x8000). For resolutions smaller than 16 bits, the non-significant bits are forced to the values shown in
Table 16-25. The output code, expressed in LSBs, corresponds to:

OSR

OUT

REF

ADC

(LSB)

(Eq.17)

Recalling equation Eq. 9, this can be rewritten as:

16-17

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Datasheet
XE88LC05/05A

REF

TOT

REF

ADC

GDoff

OUT

OSR

OSR 1

(LSB) (Eq. 18)

where, from Eq. 10 and Eq. 11, the total PGA gain and offset are respectively:

TOT

(V/V)

and:

GDoff

TOT

(V/V)

ADC Input

Voltage

IN,ADC

% of

Full

Scale

(FS)

Output in

LSBs

Output

Code

in Hex

+2.49505V

+0.5

-1

=+32'767

7FFF

+2.49497V ...

-2

=+32'766

7FFE

... ... ... ...

+76.145

... +1

0001

0V 0 0 0000

-76.145

... -1

FFFF

... ... ... ...

-2.49505V ...

-2

-1

=-32'767

8001

-2.49513V

-0.5

-2

=-32'768

8000

Table 16-24. Basic ADC Relationships (example for: V

REF

= 5V, OSR = 512, n = 16 bits)

SET_OSR

[2:0]

SET_NELC = 00

SET_NELC = 01

SET_NELC = 10

SET_NELC = 11

000 1000000000

100000000 10000000 1000000

001 10000000

1000000 100000 10000

010 100000

10000 1000 100

011 1000

100 10 1

100 10 1 - -
101

- - - -

110

- - - -

111

- - - -

Table 16-25. Last forced LSBs in conversion output registers for resolution settings

smaller than 16 bits (n < 16) (

RegAcOutMsb[7:0]

RegAcOutLsb[7:0]

)

16-18

D0304-40

Datasheet
XE88LC05/05A

The equivalent LSB size at the input of the PGA chain is:

OSR

LSB

TOT

REF

(V)

(Eq.

19)

Notice that the input voltage V

IN,ADC

of the ADC must satisfy the condition:

)

(

OSR

REFN

REFP

ADC

(V)

(Eq.

20)

to remain within the ADC input range.

16.7.8

Power Saving Modes

During low-speed operation, the bias current in the PGAs and ADC can be programmed to save
power using the control words

IB_AMP_PGA[1:0]

and

IB_AMP_ADC[1:0]

(see Table 16-26). If the

system is idle, the PGAs and ADC can even be disabled, thus, reducing power consumption to its
minimum. This can considerably improve battery lifetime.

IB_AMP_ADC

[1:0]

IB_AMP_PGA

[1:0]

ADC

Bias

Current

PGA

Bias

Current

Max. f

[kHz]

00
01
10
11

1/4

ADC

1/2

ADC

3/4

ADC

62.5

125
250
500

00
01
10
11

1/4

PGA

1/2

PGA

3/4

PGA

62.5

125
250
500

Table 16-26. ADC & PGA power saving modes and maximum sampling frequency

16.8 Specifications and Measured Curves

This section presents measurement results for the acquisition chain. A summary table with circuit
specifications and measured curves are given.

16-20

D0304-40

Datasheet
XE88LC05/05A

16.8.2 Specifications

Unless otherwise specified: Temperature T

= +25°C, V

= +5V, GND = 0V, V

REF

= +5V, V

= 0V, RC frequency f

= 2MHz,

sampling frequency f

= 500kHz, Overall PGA gain GD

TOT

= 1, offsets GDOff

= GDOff

= 0. Power operation: normal

(

IB_AMP_ADC[1:0]

IB_AMP_PGA[1:0]

= '11'). For resolution n = 12 bits: OSR = 32 and N

ELCONV

= 4. For resolution n = 16

bits: OSR = 512 and N

ELCONV

= 2.

VALUE

PARAMETER

MIN TYP MAX

UNITS COMMENTS/CONDITIONS

ANALOG INPUT
CHARACTERISTICS
Differential Input Voltage Ranges

= (V

INP

- V

INN

)

Reference Voltage Range

REF

= (V

REFP

REFN

)

-2.42
-24.2
-2.42

+2.42
+24.2
+2.42

mV
mV

Gain = 1, OSR = 32 (Note 1)
Gain = 100, OSR = 32

Gain = 1000, OSR = 32

PROGRAMMABLE GAIN
AMPLIFIERS (PGA)
Total PGA Gain, GD

TOT

PGA1 Gain, GD

PGA2 Gain, GD

PGA3 Gain, GD

Gain Setting Precision (each stage)
Gain Temperature Dependence
Offset

PGA2 Offset, GDoff

PGA3 Offset, GDoff

Offset Setting Precision (PGA2 or 3)
Offset Temperature Dependence
Input Impedance
PGA1

PGA2,

PGA3

Output RMS Noise
PGA1
PGA2
PGA3

0.5

1
1
0

-3

-1

-127/12

-3

1500

150
150

0.5

205
340
365

1000

10
10

127/12

+127/12

V/V
V/V
V/V
V/V

ppm/°C

V/V
V/V

ppm/°C

See Table 16-14
See Table 16-15
Step=1/12 V/V, See Table
16-17

Step=0.2 V/V, See Table 16-16
Step=1/12 V/V, See Table
16-18
(Note 2)

PGA1 Gain = 1 (Note 3)
PGA1 Gain = 10 (Note 3)
Maximal gain (Note 3)

(Note 4)
(Note 5)
(Note 6)

ADC STATIC PERFORMANCE
Resolution, n
No Missing Codes
Gain Error
Offset Error

Integral Non-Linearity, INL

Resolution n = 16 Bits

Differential Non-Linearity, DNL

Resolution n = 16 Bits

Power Supply Rejection Ratio, PSRR

0.15

1.0

0.5

78
72

Bits

% of FS

LSB

dB
dB

(Note 7)
(Note 8)
(Note 9)
n = 16 bits (Note 10)

(Note 11)

(Note 12)
V

= 5V

0.3V (Note 13)

= 3V

0.3V (Note 13)

DYNAMIC PERFORMANCE
Sampling Frequency, f

Conversion Time, T

CONV

Throughput Rate (Continuous Mode),
1/T

CONV

Nbr of Initialization Cycles, N

INIT

Nbr of End Conversion Cycles, N

END

PGA Stabilization Delay

0
0

133

1027

3.76
0.49

OSR

2
5

kHz

cycles/f

kSps
kSps

cycles
cycles
cycles

n = 12 bits (Note 14)
n = 16 bits (Note 14)
n = 12 bits, f

= 500kHz

n = 16 bits, f

= 500kHz

(Note 15)

DIGITAL OUTPUT
ADC Output Data Coding

Binary Two's Complement
See Table 16-24 and Table
16-25

16-21

D0304-40

Datasheet
XE88LC05/05A

Specifications (Cont'd)

VALUE

PARAMETER

MIN TYP MAX

UNITS COMMENTS/CONDITIONS

POWER SUPPLY
Voltage Supply Range, V

Analog Quiescent Current
Consumption, Total (I

)

ADC Only

PGA1

PGA2

PGA3

Analog Power Dissipation

Normal Power Mode

3/4 Power Reduction Mode

1/2 Power Reduction Mode

1/4 Power Reduction Mode

+2.4

720/620
250/190
165/150
130/120
175/160

3.6/1.9
2.7/1.4
1.8/0.9
0.9/0.5

+5.5

mW
mW
mW
mW

Only Acquisition Chain
V

= 5V/3V

All PGAs & ADC Active
V

= 5V/3V (Note 16)

= 5V/3V (Note 17)

= 5V/3V (Note 18)

= 5V/3V (Note 19)

TEMPERATURE
Specified Range
Operating Range

-40
-40

+85

+125

°C
°C

Notes:

(1) Gain defined as overall PGA gain GD

TOT

= GD

. Maximum input voltage is given by:

IN,MAX

REF

/2)

(OSR/OSR+1).

(2) Offset due to tolerance on GDoff

or GDoff

setting. For small intrinsic offset, use only ADC and PGA1.

(3) Measured with block connected to inputs through AMUX block. Normalized input sampling frequency for input

impedance is f

= 512kHz. This figure must be multiplied by 2 for f

= 256kHz, 4 for f

= 128kHz. Input impedance is

proportional to 1/f

(4)

Figure independent from PGA1 gain and sampling frequency f

. See model of Figure 16-18(a).

See equation Eq. 21 to calculate equivalent input noise.

(5) Figure independent on PGA2 gain and sampling frequency f

. See model of Figure 16-18(a). See equation Eq. 21

to calculate equivalent input noise.

(6) Figure independent on PGA3 gain and sampling frequency f

. See model of Figure 16-18(a) and equation Eq. 21 to

calculate equivalent input noise.

(7) Resolution is given by n = 2

log2(OSR) + log2(N

ELCONV

). OSR can be set between 8 and 1024, in powers of 2.

ELCONV

can be set to 1, 2, 4 or 8.

(8) If a ramp signal is applied to the input, all digital codes appear in the resulting ADC output data.
(9) Gain error is defined as the amount of deviation between the ideal (theoretical) transfer function and the measured

transfer function (with the offset error removed). (See Figure 16-19)

(10) Offset error is defined as the output code error for a zero volt input (ideally, output code = 0). For

1 LSB offset,

ELCONV

must be

(11) INL defined as the deviation of the DC transfer curve of each individual code from the best-fit straight line. This

specification holds over the full scale.

(12) DNL is defined as the difference (in LSB) between the ideal (1 LSB) and measured code transitions for successive

codes.

(13) Figures for Gains = 1 to 100. PSRR is defined as the amount of change in the ADC output value as the power

supply voltage changes.

(14) Conversion time is given by: T

CONV

= (N

ELCONV

(OSR + 1) + 1) / f

. OSR can be set between 8 and 1024, in powers

of 2. N

ELCONV

can be set to 1, 2, 4 or 8.

(15) PGAs are reset after each writing operation to registers

RegAcCfg1-5

. The ADC must be started after a PGA or

inputs common-mode stabilisation delay. This is done by writing bit

Start

several cycles after PGA settings

modification or channel switching. Delay between PGA start or input channel switching and ADC start should be
equivalent to OSR (between 8 and 1024) number of cycles. This delay does not apply to conversions made without
the PGAs.

(16) Nominal (maximum) bias currents in PGAs and ADC, i.e.

IB_AMP_PGA[1:0]

= `11' and

IB_AMP_ADC[1:0]

`11'.

(17) Bias currents in PGAs and ADC set to 3/4 of nominal values, i.e.

IB_AMP_PGA[1:0]

= `10',

IB_AMP_ADC[1:0]

`10'.

(18) Bias currents in PGAs and ADC set to 1/2 of nominal values, i.e.

IB_AMP_PGA[1:0]

= `01',

IB_AMP_ADC[1:0]

`01'.

(19) Bias currents in PGAs and ADC set to 1/4 of nominal values, i.e.

IB_AMP_PGA[1:0]

= `00',

IB_AMP_ADC[1:0]

`00'.

16-22

D0304-40

Datasheet
XE88LC05/05A

16.8.3 Linearity

16.8.3.1 Integral

non-linearity

The integral non-linearity depends on the selected gain configuration. First of all, the non-linearity of
the ADC (all PGA stages bypassed) is shown in Figure 16-8.

Figure 16-8. Integral non-linearity of the ADC (PGA disabled, reference voltage of 4.8V)

The different PGA stages have been designed to find the best compromise between the noise
performance, the integral non-linearity and the power consumption. To obtain this, the first stage has
the best noise performance and the third stage the best linearity performance. For large input signals
(small PGA gains, i.e. up to about 50), the noise added by the PGA is very small with respect to the
input signal and the second and third stage of the PGA should be used to get the best linearity. For
small input signals (large gains, i.e. above 50), the noise level in the PGA is important and the first
stage of the PGA should be used.

The following figures give the non-linearity for different gain settings of the PGA, selecting the
appropriate stage to get the best noise and linearity performance. Figure 16-9 shows the non-linearity
when the third stage is used with a gain of 1. It is of course not very useful to use the PGA with a gain
of 1 unless it is used to compensate offset. By increasing the gain, the integral non-linearity becomes
even smaller since the signal in the amplifiers reduces.

Figure 16-10 shows the non-linearity for a gain of 2. Figure 16-11 shows the non-linearity for a gain of
5. Figure 16-12 shows the non-linearity for a gain of 10. By comparing these figures to Figure 16-8, it
can be seen that the third stage of the PGA does not add significant integral non-linearity.

Figure 16-13 shows the non-linearity for a gain of 20 and Figure 16-14 shows the non-linearity for a
gain of 50. In both cases the PGA2 is used at a gain of 10 and the remaining gain is realized by the
third stage. It can be seen again that the second stage of the PGA does not add significant non-
linearity.

For gains above 50, the first stage PGA1 should be selected in stead of PGA2. Although the non-
linearity in the first stage of the PGA is larger than in stage 2 and 3, the gain in stage 3 is now
sufficiently high so that the non-linearity of the first stage does become negligible as is shown in
Figure 16-15 for a gain of 100. Therefor, the first stage is preferred over the second stage since it has
less noise.

Increasing the gain further up to 1000 will further increase the linearity since the signal becomes very
small in the first two stages. The signal is full scale at the output of stage 3 and as shown in Figure
16-9 to Figure 16-12, this stage has very good linearity.

16-26

D0304-40

Datasheet
XE88LC05/05A

Figure 16-16. Differential non-linearity of the ADC converter.

16.8.4 Noise

Ideally, a constant input voltage V

should result in a constant output code. However, because of

circuit noise, the output code may vary for a fixed input voltage. Thus, a statistical analysis on the
output code of 1200 conversions for a constant input voltage was performed to derive the equivalent
noise levels of PGA1, PGA2, and PGA3. The extracted rms output noise of PGA1, 2, and 3 are given
in Table 16-27: standard output deviation and output rms noise voltage. Figure 16-17 shows the
distribution for the ADC alone (PGA1, 2, and 3 bypassed). Quantization noise is dominant in this case,
and, thus, the ADC thermal noise is below 16 bits.

The simple noise model of Figure 16-18(a) is used to estimate the equivalent input referred rms noise
V

N,IN

of the acquisition chain in the model of Figure 16-18(b). This is given by the relationship:

)

(

))

(

))

(

)

(

ELCONV

OSR

rms) (Eq.

21)

where V

, V

, and V

are the output rms noise figures of Table 16-27, GD

, GD

, and GD

are the

PGA gains of stages 1 to 3 respectively. As shown in this equation, noise can be reduced by
increasing OSR and N

ELCONV

(increases the ADC averaging effect, but reduces noise).

Parameter

PGA1 PGA2 PGA3

Standard deviation at

ADC output (LSB)

0.85

1.4

1.5

Output rms noise (

205 (V

)

340

)

365

)

Note: see noise model of Figure 16-18 and equation Eq. 21.

Table 16-27. PGA noise measurements (n = 16 bits, OSR = 512, N

ELCONV

= 2, V

REF

= 5V)

16-27

D0304-40

Datasheet
XE88LC05/05A

-5

-4

-3

-2

-1

Output Code Deviation From Mean Value [LSB]

curence

[
%

f
to

t
a

l s

les

]

Figure 16-17. ADC noise (PGA1, 2 & 3 bypassed, OSR=512,N

ELCONV

=2)

PGA1

PGA2

PGA3

ADC

GD1

GD2

GD3

(a)

PGA1

PGA2

PGA3

ADC

GD1

GD2

GD3

N,IN

(b)

Figure 16-18. (a) Simple noise model for PGAs and ADC

and (b) total input referred noise

As an example, consider the system where: GD

= 10 (GD

= 1; PGA3 bypassed), OSR = 512,

ELCONV

= 2, V

REF

= 5V. In this case, the noise contribution V

of PGA1 is dominant over that of

PGA2. Using equation Eq. 21, we get: V

N,IN

= 6.4

V (rms) at the input of the acquisition chain, or,

equivalently, 0.85 LSB at the output of the ADC. Considering a 0.2V (rms) maximum signal amplitude,
the signal-to-noise ratio is 90dB.

Noise can also be reduced by implementing a software filter. By making an average on a number of
subsequent measurements, the apparent noise is reduced the square root of the number of
measurement used to make the average.

16.8.5

Gain Error and Offset Error

Gain error is defined as the amount of deviation between the ideal transfer function (theoretical
equation Eq. 18) and the measured transfer function (with the offset error removed).

The actual gain of the different stages can vary depending on the fabrication tolerances of the
different elements. Although these tolerances are specified to a maximum of

3%, they will be most of

the time around

0.5%. Moreover, the tolerances between the different stages are not correlated and

the probability to get the maximal error in the same direction in all stages is very low. Finally, these
gain errors can be calibrated by the software at the same time with the gain errors of the sensor for
instance.

16-28

D0304-40

Datasheet
XE88LC05/05A

Figure 16-19 shows gain error drift vs. temperature for different PGA gains. The curves are expressed
in % of Full-Scale Range (FSR) normalized to 25°C.

Offset error is defined as the output code error for a zero volt input (ideally, output code = 0). The
offset of the ADC and the PGA1 stage are completely suppressed if N

ELCONV

> 1.

The measured offset drift vs. temperature curves for different PGA gains are depicted in Figure 16-20.
The output offset error, expressed in LSB for 16-bit setting, is normalized to 25°C. Notice that if the
ADC is used alone, the output offset error is below

1 LSB and has no drift.

NORMALIZED TO 25°C

-0.4

-0.3

-0.2

-0.1

0.0

0.1

0.2

-50

-25

100

Temperature [°C]

r
r
o

r
[%

f
F

]

1
5
20
100

Figure 16-19. Gain error vs. temperature for different PGA gains

NORMALIZED TO 25°C

-40

-20

100

-50

-25

100

Temperature [°C]

t
O

f
fs

t
E

r
r
o

r
[L

]

1
5
20
100

Figure 16-20. Offset error vs. temperature for different PGA gains

16.8.6 Power

Consumption

Figure 16-21 plots the variation of quiescent current consumption with supply voltage V

, as well as

the distribution between the 3 PGA stages and the ADC (see Table 16-28). As shown in Figure 16-22,
if lower sampling frequency is used, the quiescent current consumption can be lowered by reducing
the bias currents of the PGAs and the ADC with registers

IB_AMP_PGA [1:0]

and

IB_AMP_ADC

[1:0]

. (In Figure 16-22,

IB_AMP_PGA/ADC[1:0]

= '11', '10', '00' for f

= 500, 250, 62.5kHz

respectively.)

Quiescent current consumption vs. temperature is depicted in Figure 16-23, showing a relative
increase of nearly 40% between -45 and +85°C. Figure 16-24 shows the variation of quiescent current

16-29

D0304-40

Datasheet
XE88LC05/05A

consumption for different frequency settings of the internal RC oscillator. It can be seen that the
quiescent current varies by about 20% between 100kHz and 2MHz.

100

200

300

400

500

600

700

800

2.5

3.0

3.5

4.0

4.5

5.0

5.5

Supply Voltage - V

DDA

[V]

i
e

s
c
e

t C

r
r
e

t
- I

[

No PGAs, ADC only

PGA1 + ADC

PGA1 & 2 + ADC

PGA1, 2 & 3 + ADC

Figure 16-21. Quiescent current consumption vs. supply voltage

100

200

300

400

500

600

700

800

2.5

3.0

3.5

4.0

4.5

5.0

5.5

Supply Voltage - V

DDA

[V]

i
e

s
c
e

t Cu

r
r
e

t
- I

[

500kHz

Sampling Frequency f

250kHz

62.5kHz

Figure 16-22. Quiescent current consumption vs. supply voltage for different sampling

frequencies

500

550

600

650

700

750

800

850

900

-50

-25

100

125

Temperature [°C]

t C

r
r
e

t
-

[

-25

-20

-15

-10

-5

-50

-25

100

125

Temperature [°C]

l
a
t
i
ve

i
e

s
c
en

t
C

r
r
en

t
C

a
n

/ I

°
C

]

(a)

(b)

Figure 16-23. (a) Absolute and (b) relative change inquiescent current consumption vs.

temperature

16-30

D0304-40

Datasheet
XE88LC05/05A

Supply

ADC PGA1 PGA2

PGA3 TOTAL Unit

= 5V

250

165 130 175 720

= 3V

190

150 120 160 620

Table 16-28. Typical quiescent current distributions in acquisition chain (n = 16 bits, f

500kHz)

-20

-15

-10

-5

500

1000

1500

2000

2500

3000

3500

Frequency - f

[kHz]

Rel

a
t
i
v
e

Q

i
e
sc

t
Cur

r
ent

Chan

2
M

]

500

550

600

650

700

750

800

850

500

1000

1500

2000

2500

3000

3500

Frequency - f

[kHz]

i
esc

ent

r
r
e
nt

[

(a)

(b)

Figure 16-24. (a) Absolute and (b) relative change in quiescent curent consumption vs.

RC oscillator frequency (all PGAs active, V

= 5V)

16.8.7

Power Supply Rejection Ratio

Figure 16-25 shows power supply rejection ratio (PSRR) at 3V and 5V supply voltage, and for various
PGA gains. PSRR is defined as the ratio (in dB) of voltage supply change (in V) to the change in the
converter output (in V). PSRR depends on both PGA gain and supply voltage V

100

105

100

PGA Gain [V/V]

RR [

VDD=3V
VDD=5V

Figure 16-25. Power supply rejection ratio (PSRR)

16-31

D0304-40

Datasheet
XE88LC05/05A

Supply

GAIN = 1

GAIN =5

GAIN = 10

GAIN = 20

GAIN =100

Unit

= 5V

100

72 79 90 90 86

Table 16-29. PSRR (n = 16 bits, V

= V

REF

= 2.5V, f

= 500kHz)

16.9 Application

Hints

16.9.1 Input

Impedance

The PGAs of the acquisition chain employ switched-capacitor techniques. For this reason, while a
conversion is done, the input impedance on the selected channel of the PGAs is inversely proportional
to the sampling frequency f

and to stage gain as given in equation 22.

gain

768

(Eq.

22)

The input impedance observed is the input impedance of the first PGA stage that is enabled or the
input impedance of the ADC if all three stages are disabled.

PGA1 (with a gain of 10), PGA2 (with a gain of 10) and PGA3 (with a gain of 10) each have a
minimum input impedance of 150k

at f

= 512kHz (see Specification Table). Larger input impedance

can be obtained by reducing the gain and/or by reducing the sampling frequency. Therefor, with a
gain of 1 and a sampling frequency of 100kHz, Z

> 7.6M

The input impedance on channels that are not selected is very high (>100M

16.9.2

PGA Settling or Input Channel Modifications

PGAs are reset after each writing operation to registers

RegAcCfg1-5

. Similarly, input channels are

switched after modifications of

AMUX[4:0]

VMUX

. To ensure precise conversion, the ADC must be

started after a PGA or inputs common-mode stabilization delay. This is done by writing bit

START

several cycles after PGA settings modification or channel switching. Delay between PGA start or input
channel switching and ADC start should be equivalent to OSR (between 8 and 1024) number of
cycles. This delay does not apply to conversions made without the PGAs.

If the ADC is not settled within the specified period, there is most probably an input impedance
problem (see previous section).

16.9.3

PGA Gain & Offset, Linearity and Noise

Hereafter are a few design guidelines that should be taken into account when using the
ZoomingADC

1) Keep in mind that increasing the overall PGA gain, or "zooming" coefficient, improves

linearity but degrades noise performance.

2) Use the minimum number of PGA stages necessary to produce the desired gain ("zooming")

and offset. Bypass unnecessary PGAs.

3) For high gains (>50), use PGA stage 1. For low gains (<50) use stages 2 and 3.
4) For the lowest noise, set the highest possible gain on the first (front) PGA stage used in the

chain. For example, in an application where a gain of 20 is needed, set the gain of PGA2 to
10, set the gain of PGA3 to 2.

16-32

D0304-40

Datasheet
XE88LC05/05A

4) For highest linearity and lowest noise performance, bypass all PGAs and use the ADC alone

(applications where no "zooming" is needed); i.e. set

ENABLE[3:0]

= '0001'.

5) For low-noise applications where power consumption is not a primary concern, maintain the

largest bias currents in the PGAs and in the ADC; i.e. set

IB_AMP_PGA[1:0]

IB_AMP_ADC[1:0]

= '11'.

6) For lowest output offset error at the output of the ADC, bypass PGA2 and PGA3. Indeed,

PGA2 and PGA3 typically introduce an offset of about 5 to 10 LSB (16 bit) at their output.
Note, however, that the ADC output offset is easily calibrated out by software.

16.9.4 Frequency

Response

The incremental ADC is an over-sampled converter with two main blocks: an analog modulator and a
low-pass digital filter. The main function of the digital filter is to remove the quantization noise
introduced by the modulator. As shown in Figure 16-26, this filter determines the frequency response
of the transfer function between the output of the ADC and the analog input V

. Notice that the

frequency axes are normalized to one elementary conversion period OSR/f

. The plots of Figure

16-26 also show that the frequency response changes with the number of elementary conversions
N

ELCONV

performed. In particular, notches appear for N

ELCONV

2. These notches occur at:

ELCONV

NOTCH

OSR

)

(

(Hz)

for

)

(

,...,

ELCONV

(Eq.

23)

and are repeated every f

/OSR.

Information on the location of these notches is particularly useful when specific frequencies must be
filtered out by the acquisition system. For example, consider a 5Hz-bandwidth, 16-bit sensing system
where 50Hz line rejection is needed. Using the above equation and the plots below, we set the 4th
notch for N

ELCONV

= 4 to 50Hz, i.e. 1.25

/OSR = 50Hz. The sampling frequency is then calculated as

= 20.48kHz for OSR = 512. Notice that this choice yields also good attenuation of 50Hz harmonics.

0.2

0.4

0.6

0.8

1.2

Normalized Frequency - f *(OSR/f

) [-]

r
m

l
iz

[
-
]

ELCONV

= 1

0.2

0.4

0.6

0.8

1.2

Normalized Frequency - f *(OSR/f

) [-]

r
m

l
i
z
e

i
t
u

[-]

ELCONV

= 2

0.2

0.4

0.6

0.8

1.2

Normalized Frequency - f *(OSR/f

) [-]

r
m

l
i
z
e

i
tu

[-]

ELCONV

= 4

0.2

0.4

0.6

0.8

1.2

Normalized Frequency - f *(OSR/f

) [-]

r
m

l
i
z
e

i
tu

[-]

ELCONV

= 8

Figure 16-26. Frequency response: normalized magnitude vs. frequency for different

ELCONV

17-2

D0304-40

Datasheet
XE88LC05/05A

17.1 Features

Generates a voltage that is higher or equal to the supply voltage.

Can be easily enabled or disabled

17.2 Overview

The Vmult block generates a voltage (called "Vmult") that is higher or equal to the supply voltage. This
output voltage is used in the acquisition chain.

The voltage multiplier should be on (bit ENABLE in RegVmultCfg0) when using the acquisition chain
or analog properties of the Port B while VBAT is below 3V. If the multiplier is enabled, the external
capacitor on the pin VMULT is mandatory.

The source clock of Vmult is selected by FIN[1:0] in RegVmultCfg0. It is strongly recommended to
use the same settings as in the ADC.

17.3 Control

register

There is only one register in the Vmult. Table 177-1 describes the bits in the register.

Pos. RegVmultCfg0

Reset

Function

2 Enable

0
resetsystem

enable of the vmult
`1' : enabled
`0' : disabled

1-0 Fin

rw 0

resetsystem

system clock division factor
`00' : 1/2,
`01' : 1/4,
`10' : 1/16,
`11' : 1/64

Table 177-1. RegVmultCfg0

17.4 External

component

When the multiplier is enabled, a capacitor has to be connected to the VMULT pin. If the multiplier is
disabled, the pin may remain floating.

Min.

Max.

Note

Capacitor on VMULT

1.0

3.0

18-2

D0304-40

Datasheet
XE88LC05/05A

18.1 Features

16-bits maximum input word width

Synchronization mechanism to guarantee data integrity when writing LSB and MSB 8-bits

data

Programmable noise shaper order: second, first or order zero

Programmable PWM modulation between 4 and 11-bits

Programmable clock input frequency: fin or fin/2

Programmable output polarity: active high or low

On chip amplifier for analog filtering, voltage output or 4-20 mA loop

18.2 Overview of Signal DAC - The generic DAC

The generic DAC block consists of two major parts: the noise shaper (sigma-delta modulator) and the
PWM modulator as shown in Figure 18-1.

control

Sigma-delta

modulator

PWM

modulator

CPU
bus

4-11
m

DAS Out

amp

Figure 18-1. General block diagram

A D/A converter that is built with a digital PWM modulator needs a high clock frequency for a small
signal bandwidth. For a 10 bit digital PWM modulator for instance, a 10 bit counter is needed in order
to create a pulse with a resolution of 1024. This means that, in case an infinitely sharp analog output
filter is used, the clock frequency has to be at least 1024 times the output bandwidth. In practice
however, in order to be able to build the analog filter, the clock frequency needs to be much higher.

In order to reduce this frequency requirement, the input digital word is broken down into n words with
a smaller width m by a noise shaper so that the "average" (average for first order noise shaper, more
complicated for higher order noise shapers) value of the n m-bit words represents the full width input
code. Instead of 1 pulse with the full resolution, the PWM modulator now generates n pulses with a
smaller resolution m. This increases the output pulse repetition frequency with a factor n for identical
clock frequency. Therefore, the analog output filtering is easier to implement. Higher order noise
shapers (order >1) allow to decrease the clock frequency for identical signal bandwidth.

Another advantage is that the signal distortion is less dependent on the signal value. A disadvantage
is however, that the output signal after filtering is more dependent on the rise and fall times of the
PWM output since there are many more pulses.

The maximum word width at the input is 16-bit. If the word is narrower, 0's have to be added after the
LSB. In order to maintain maximum flexibility, the order of the noise shaper and the resolution of the
PWM modulation are programmable by writing the codes CodeLmax and NsOrder to the
configuration register. The possible noise shaper order is 0 (which means no noise shaping), 1 or 2.
The possible PWM modulation resolution m can be set between 4 and 11.

18-3

D0304-40

Datasheet
XE88LC05/05A

18.3 Registers Map

All registers are reset with the system reset.

The contents of the registers RegDasInLsb and RegDasInMsb are transferred to the D/A converter
when after data have been written into RegDasInMsb. Therefore, in order to maintain the
synchronisation between the LSB and MSB, the LSB should always be written before the MSB.

Pos. RegDasInLsb

reset

function

7-0 DasInLsb(7:0)

rw 0

resetsystem

Data to convert LSB

Table 18-1. RegDasInLsb

Pos. RegDasInMsb

reset

function

7-0 DasInMsb(7:0)

rw 0

resetsystem

Data to convert MSB

Table 18-2. RegDasInMsb

Pos. RegDasCfg0

reset

function

7:6

NsOrder(1:0)

00
resetsystem

Noise Shaper order
00 : order 0
01 : order 1
1x : order 2

5:3

CodeLmax(2:0)

000
resetsystem

PWM pulse resolution :
000 : 4 bits
001 : 5 bits
010 : 6 bits
011 : 7 bits
100 : 8 bits
101 : 9 bits
110 : 10 bits
111 : 11 bits

2:1

Enable(1:0)

00
resetsystem

Bit 0 : enables the D/A
Bit 1 : enables the amplifier

Fin

0
resetsystem

Input frequency of modulator as a fraction of
oscillator frequency
0 : 1.f

, 1 : ½.f

Table 18-3. RegDasCfg0

Pos. RegDasCfg1

reset

function

7:2 -

rw 000000

Unused

1 BW

0
resetsystem

Amplifier bandwidth
0 : small bandwidth
1 : large bandwidth

0 INV

0
resetsystem

Inverts the PWM output
0 : normal, active high
1 : inverted, active low

Table 18-4. RegDasCfg1

18-4

D0304-40

Datasheet
XE88LC05/05A

18.4 The D/A description

The D/A converter consists of 2 parts: a classic PWM modulator which is preceded by a noise shaper
(Figure 18-1). The PWM signal has then to be low pass filtered using the amplifier and external
components to obtain the analog signal.

18.4.1

What is a noise shaper?

The major disadvantage of using a PWM modulator to generate a high resolution analog signal is that
it requires a high ratio between the PWM switching frequency and the useful bandwidth of the output
analog signal after low pass filtering.

Example: assuming the switching frequency of the PWM modulator is 1MHz and one wants to resolve
16 bit, i.e. 2

=65536 steps. In this case, the PWM has to code each step in increments of

1µs=1/1MHz and needs therefore 65536µs per pulse. This means that the PWM pulse repetition rate
is 1/65536µs=15.25Hz. So, even with a higher order low pass filter, more than 1 frequency decade
will be required to filter the PWM signal down to a 16 bit accurate analog signal. This leaves a useful
bandwidth below 1Hz.

The goal of the noise shaper is to reduce the ratio between the PWM switching frequency and the
useful bandwidth. The noise shaper will not reduce the "truncation noise" and "PWM modulation
noise" but move it to higher frequencies. It "shapes" the frequency spectrum ("noise") of the generated
PWM signal, hence its name. In practice, the noise shaper allows the generation of a signal with a
given resolution using a PWM modulator that has a lower resolution. The noise shaper then
generates a series of different subsequent low resolution codes for the PWM so that the average
value corresponds to the high resolution code.

The first order noise shaper interpolates between two adjacent PWM codes to obtain a higher
resolution. The second order noise shaper can use non-adjacent PWM codes.

Example for first order noise shaper: assuming again the resolution of 16 bits using a 1MHz PWM
switching frequency using the noise shaper with order 1. If a PWM modulator with 4 bits, i.e. 16 steps
is used, the PWM repetition frequency becomes then 1MHz/16=62.5kHz. The PWM modulator can
convert only the 4 MSB's of the 16 bit input such as h0000, h1000 until hF000. In order to convert the
code h5800, which is between h5000 and h6000? In this case, the first order noise shaper will
interpolate by presenting alternatively the code h5 and h6 to the PWM so that after filtering a signal is
obtained halfway between the normal PWM steps. To convert the code h5400, it will present h5 3
times and h6 once to the PWM and so on. It is clear from this that the PWM repetition frequency is
much higher than for the simple PWM and can be filtered out more easily. The quantization noise
frequency will depend on the code to be converted: for this example for instance we need two PWM
pulses to implement the code h5800, but we need four to implement h5400 etc.

Example for second order noise shaper: if we use the same conditions as for the example above, we
will obtain the same PWM repetition frequency. However, to implement the code h5400, the noise
shaper now can present the following sequence to the PWM modulator: h6, h5, h6, h4. This increases
the frequency components at the PWM pulse repetition frequency and ½ of the PWM pulse repetition
frequency but at the same time reduces energy at ¼ of the PWM pulse repetition frequency with
respect to the first order noise shaper. The low pass cut-off frequency can therefore be higher than for
a first order noise shaper.

A disadvantage of the second order noise shaper is however that the resolution will drop when the
code is very close to h0000 or hFFFF.

Example: if we assume the same conditions as above, but we want to convert the code h0400. It is
now impossible to use a similar sequence as above (which would be h1, h0, h1, h(-1) ) due to
saturation of the code. There is no choice left but the sequence h1 h0 h0 h0 which is the same
sequence as in the first order noise shaper.

18-5

D0304-40

Datasheet
XE88LC05/05A

18.4.2 Advantages/disadvantages

Advantages:
Using a high order noise shaper together with a PWM modulator with low resolution reduces the ratio
between the low pass cut off frequency and the PWM switching frequency for the same total
resolution. This can be used to increase the output signal bandwidth or to reduce the PWM switching
frequency and therefore the power consumption of the D/A. Signal distortion is less dependent on the
signal value.

Disadvantages:
Using a high order noise shaper together with a PWM modulator with low resolution will use lots of
short pulses in stead of 1 long pulse. The D/A is therefore more sensitive to rise and fall times of the
PWM resulting in a slightly higher non-linearity and temperature dependence. The second order noise
shaper also has a reduced resolution for codes very close to zero or full scale.

18.4.3

D/A setup and resolution

In this section, the resolution that can be obtained with the D/A as a function of settings is calculated.
These calculations are based on the quantization and PWM modulation noise. Noise on the
reference, i.e. the supply voltage is not taken into account. High frequency noise on the supply
voltage can be filtered by the output low pass filter, but in band noise on the reference will show up in
the output signal with amplitude that will depend on the signal value. Therefore, when using the D/A,
one should take care to minimize the switching activity on the digital ports and/or to limit the load on
these ports.

18.4.3.1 Noise shaper of order 0

Setting the noise shaper to order 0 (NsOrder=00), reduces the D/A to a regular PWM. Two
parameters are setting the resolution of the D/A: the resolution of the modulator itself and the amount
of low pass filtering at the output.

The modulation width

of the PWM modulator is given by:

CodeLmax

The cut-off frequency

of the low pass filter required to get the resolution is calculated below. The

PWM modulator repetition frequency

PWM

can be calculated as a function of the selected

modulation width

, the frequency of the RC oscillator of the circuit

and the selected frequency

division set by Fin :

PWM

Fin

To obtain an analog signal with the required solution, the PWM signal has to be low pass filtered. The
resolution that can be obtained depends on the filter order and the ratio between the PWM modulation
frequency

PWM

and the filter cut-off frequency

. For a low pass filter of LpOrder, we obtain:

PWM

LpOrder

resolution

log

The total resolution of the D/A is then the minimal value of both criteria:

18-6

D0304-40

Datasheet
XE88LC05/05A

)

min(

PWM

resolution

In Table 18-5 the required cut-off frequency of the low pass filter is shown for a noise shaper of order
0 as a function of the desired resolution for both a first and second order low pass filter. The PWM
modulation factor m should be chosen equal to the desired resolution.

resolution (bit)

for LpOrder=1 (Hz)

for LpOrder=2 (Hz)

4 4

7812

31250

5 5

1953

11048

6 6

488

3906

7 7

122

1381

8 8

488

9 9

7.6

172

10 10

1.9

11 11

0.48

Table 18-5. Signal bandwidth as a function of the required resolution for the PWM without noise

shaper (Fin=0, NsOrder=00, f

=2MHz).

18.4.3.2 Noise shaper of order 1 or 2

The calculation on the required low pass cut-off frequency given in 18.4.3.1 remains valid in this case.
However, the noise shaper allows using smaller PWM modulation for the same resolution. This
increases the PWM modulation frequency and as a consequence increases the output bandwidth.

An additional criterion however shows up: the filtering of the quantization noise. As can be seen from
the examples in 18.4.1, the interpolation between PWM codes generated by the noise shaper
introduce sequences at frequencies below the PWM modulation frequency. Assuming a low pass filter
that has at least the same order as the noise shaper, the resolution is given by (NsOrder1) :

)

(

log

359

PWM

quant

NsOrder

resolution

The total resolution of the D/A is then the minimal of both criteria:

)

min(

PWM

quant

resolution

Table 18-6 and Table 18-7 show the signal bandwidth that can be obtained as a function of required
resolution and PWM modulation for first and second order noise shapers. It can be seen that these
options are useful to obtain high resolution using low PWM modulation m. For high PWM modulation
m, the resolution is limited by the PWM modulator and adding a noise shaper does not change
anything.

18-7

D0304-40

Datasheet
XE88LC05/05A

NsOrder=1, f

=2MHz, Fin=0, LpOrder=2

Resolution

PWM modulation m

(bit)

1596.4

976.6

488.3

244.1

122.1

61.0

798.2

690.5

345.3

172.6

86.3

43.2

399.1

244.1

122.1

61.0

30.5

199.5

172.6

86.3

43.2

21.6

99.8

61.0

30.5

15.3

49.9

43.2

21.6

10.8

24.9

15.3

7.6

12.5

10.8

5.4

6.2

3.8

Table 18-6. Low pass cut-off frequency as a function of the selected PMW modulation and required

resolution for a first order noise shaper.

NsOrder=2, f

=2MHz, Fin=0, LpOrder=2

Resolution

PWM modulation m

(bit)

5638.4

3906.3

1953.1

976.6

488.3

244.1

122.1

61.0

3986.9

2762.1

1381.1

690.5

345.3

172.6

86.3

43.2

2819.2

1953.1

976.6

488.3

244.1

122.1

61.0

30.5

1993.5

1381.1

690.5

345.3

172.6

86.3

43.2

21.6

1409.6

976.6

488.3

244.1

122.1

61.0

30.5

15.3

996.7

690.5

345.3

172.6

86.3

43.2

21.6

10.8

704.8

488.3

244.1

122.1

61.0

30.5

15.3

7.6

498.4

345.3

172.6

86.3

43.2

21.6

10.8

5.4

352.4

244.1

122.1

61.0

30.5

15.3

7.6

3.8

Table 18-7. Low pass cut-off frequency as a function of the selected MPW modulation and required

resolution for a second order noise shaper.

The output range of the D/A is for code 0h0000 is VSS and for code 0hFFFF is (VBAT-VSS)(2

-1)/2

18.5 Amplifier

The amplifier can be used to implement the low pass filter and/or a 4-20mA loop. The amplifier is
enabled using the bit Enable(1)=1. The amplifier has two different modes selected by the bit BW: a
low frequency mode (BW=0) that allows driving a high capacitive load and a high frequency mode
(BW=1).

The first mode is particularly adapted when a voltage output is used. The second mode is more
adapted for a 4-20mA loop since loads are small and higher bandwidth is required to reject current
consumption changes in the loop.

Table 18-8 shows the specification of the amplifier.

Note that the amplifier can not be used to generate signals that are larger than the supply voltages
VBAT and VSS since the amplifier inputs and outputs are clamped to these voltages. The amplifier
inputs and outputs should stay within the input and output ranges specified below.

18-8

D0304-40

Datasheet
XE88LC05/05A

sym

description

min

typ

max

unit

Comment

gain

gain at DC

100

GBW

gain bandwidth product

kHz

capacitive

load

5 nF

GBW

gain bandwidth product

250

450

kHz

capacitive

load

200 pF

phase margin

resistive

load

SR slew

rate

kV/s

CMR

common mode input range

VSS-0.2

VBAT-1.2 V

OR output

range

VSS+0.2

VBAT-0.2

off

offset

CMRR common mode rejection

noise

integrated input noise

100

Vrms

PSRR power supply rejection

ratio

20 60

dB 4

quie

quiescent bias current

150

off

current

For the minimal resistive load and the maximal capacitive load

The amplifier common mode is VSS in the 4-20mA loop.

3. At

At DC. Only a low rejection ratio is needed since the D/A output refers directly to the power supplies.

Short circuit protection at >3mA.

6. GBW when the maximal load is cl0 and with the bit BW=0
7.

GBW when the maximal load is cl1 and with the bit BW=1

8. In both cases BW=0 and BW=1 for the maximal capacitive load and the minimal resistive load.
9.

For maximal load C

, BW=0 and maximal resistive load R

Table 18-8. Specification of the amplifier.

18.6 Low pass filter

Several low pass filters are proposed here as examples. Other filter types are possible depending on
the features or constraints of the application.

If the filter is inverting the signal, the bit INV can be used to invert the D/A output. This inversion does
not need to be done by calculation.

A first or second order low pas filter can be built with the amplifier. If higher order filters are needed,
additional first or second order sections can be added using external amplifiers.

18.6.1

First order low pass filter

Figure 18-2 shows a possible implementation of a first order low pass filter. Ideally, the analog ground
should be halfway between VBAT and VSS. The gain G and cut-off frequency f

of such a filter are

given by:

18-9

D0304-40

Datasheet
XE88LC05/05A

As an example, to obtain a 1kHz filter with unity gain, we can choose C=1nF and R1=R2=150k.

XE88LCxx

DAS_OUT

DAS_AI_M

DAS_AO

DAS_AI_P

amp

analog ground

c
o
n

Figure 18-2. First order low pass filter.

18.6.2

Second order low pass filter

Figure 18-3 shows an example of a second order low pass filter using the multi-feedback architecture.
The gain G, cut-off frequency f

and the damping factor (or quality factor Q) as a function of the

factors k and m (see Figure 18-3) are given by:

kmn

)

(

For a second order Butterworth filter,

. For smaller damping factors, the filter is under

damped resulting in overshoots on the step response. For higher damping factors, the filter is over
damped resulting in a smooth but slower step response.

An example of a 1dB ripple Chebychev filter with a cut-off frequency of about 1.5kHz and a DC gain of
1 is given by choosing m=0.22, k=1, n=0.5, R=330k and C=1nF. The resistor nR can be rounded to
180k.

A 60Hz unity gain low pass Butterworth filter can be built choosing R=180k, C=12nF, k=1, m=0.183,
n=8.33.

Note that parasitic capacitors between the DAS_OUT node and the filter output DAS_AO will
adversely affect the high frequency behavior of the filter. Care should be taken when routing these
signals.

18-10

D0304-40

Datasheet
XE88LC05/05A

XE88LCxx

DAS_OUT

DAS_AI_M

DAS_AO

DAS_AI_P

amp

analog ground

R C

mC kR

o
n

Figure 18-3. Second order low pass filter.

18.7 4-20mA

loop

18.7.1

2-wire loop with first order filtering

The amplifier can be used to build a 4-20mA loop externally. Figure 18-4 shows the principle of such
a 2-wire loop using a first order low pass filter.

In a 2-wire loop, the current consumption of the sensor and read-out electronics is drawn on the same
wires as the signal current. The current consumption of the sensor and read-out electronics should
therefore remain below 4mA. The signal current is then added by the bipolar transistor. The resistors
R

lim1

and R

lim2

are added to protect the bipolar transistor against high transient currents during power-

up. R

lim1

is generally set to a few k. The value of R

lim2

is chosen as a function of the external loop

voltage V

EXT

and the transistor saturation voltage V

CEsat

sense

CEsat

EXT

)

(

lim

If V

EXT

is larger than 5.5V, a voltage regulator has to be inserted. Since the quiescent current of the

regulator adds up to the 4mA budget, a component with sufficiently low quiescent current has to be
selected.

The resistor R

sense

measures the total current in the loop (if R

sense

<<R

). The resistors R

and R

are

used to set the gain and R

and C

to set the bandwidth of the filter. The resistor R

offset

adds an offset

to the filter voltage so that the code 0 of the D/A corresponds to 4mA. The amplifier will force a current
through the bipolar transistor so that the voltage on the filter V

and VSS on R

sense

is equal. This

transforms the filter voltage into a loop current I

loop

=(VSS-V

EXT

-)/R

sense

18-11

D0304-40

Datasheet
XE88LC05/05A

The resistor value R

sense

is generally chosen between 50 and 150 resulting in a 1V to 3V voltage

drop at maximal loop current. The resistor R

is then chosen much larger depending on the current

error requirement. Allowing for an error of 0.1% gives R

sense

/0.001.

The resistor R

offset

may be omitted but it will reduce the useful code range of the D/A.

Using the large bandwidth of the amplifier is recommended since this increases the rejection of supply
current variations of the other components in the loop. A bypass capacitor between VBAT and VSS
will also reduce the high frequency current variations. Values will depend on the voltage regulator
used. The software in the XE88LC05 should keep the current supply of the circuit as stable as
possible. This means that the clock frequency should kept constant, peripherals should not be
switched on and off, the current in the sensor is kept constant, the processor should not use the halt
or sleep modes, etc.

XE88LCxx VBAT

DAS_OUT

DAS_AI_P

DAS_AO

DAS_AI_M

VSS

c
o
n

t
r

amp

4-20mA

sense

lim1

lim2

Voltage

regulator

4-20mA

offset

Sensor

EXT

VSS

VBAT

Figure 18-4. 2-wire 4-20mA loop with first order filter

The resistor R

can then be calculated to set the full scale D/A code range (depends on the PWM

modulation m, see section 18.4.3.2) equal to the full scale signal current of 16mA:

VSS

VBAT

sense

)

(

)

(

The resistor R

offset

can be calculated in order to obtain a 4mA current while the D/A code is 0:

18-12

D0304-40

Datasheet
XE88LC05/05A

VSS

VBAT

sense

offset

)

(

The capacitor C

can be calculated from the first order filter cut-off frequency f

As an example, for VBAT-VSS=5V, m=4, R

sense

=50, V

EXT

=30V and a 1kHz low pass filter, we can

use:

lim1

=1k, R

lim2

=1k, R

=560k, R

=100k, R

offset

=2.4M, C

=1.8nF.

18.7.2

2-wire loop with second order filtering

A second order filter function can be implemented by replacing the resistor R

in Figure 18-4 by

another first order filter section as shown in Figure 18-5. The value of R

f1a

f2a

has to be chosen the

same way as R

in the first order schematic.

XE88LCxx VBAT

DAS_OUT

DAS_AI_P

DAS_AO

DAS_AI_M

VSS

c
o
n

amp

4-20mA

sense

f1a

lim1

lim2

Voltage

regulator

4-20mA

offset

Sensor

EXT

VSS

VBAT

f1b

Figure 18-5. 2-wire 4-20mA loop with second order filtering.

Another possibility is shown in Figure 18-6. The advantage this solution is that it is easier to stabilize
depending on the component parasitics and board layout. But since it limits the bandwidth of the
current regulation loop, it reduces the rejection of the supply current variations.

For this schematic, all the equations of the first order schematic remain valid. The values of R

and

can be calculated from the cut-off frequency:

19-3

D0304-40

Datasheet
XE88LC05/05A

19.4 D/A

specification

The D/A generates a voltage on node DAB_OUT that is proportional to the code RegDabIn in
between the positive reference voltage DAB_R_P and the negative reference voltage DAB_R_M. The
voltage on DAB_R_P always has to be larger than the voltage on DAB_R_M. The D/A is intended for
very low frequency use. The specification is given in Table 19-3. Larger than 100pF capacitors are
allowed on the node DAB_OUT, but the step response will increase proportionally.

sym

description

min

typ

max

unit

note

wda

number of input bits

bits

tstep step

response

0.25

ms 1

D/A output range

DAB_R_M

DAB_R_P

refp DAB_R_P

range

VSS+2.3

VBAT V

refn DAB_R_M

range

VSS

VBAT-2.3

1. Time to reach the final value within 5%, C

on DAB_OUT smaller than 100pF.

Table 19-3. D/A specification.

19.5 Amplifier

specification

The amplifier output stage is a single transistor follower that is able to drive large currents. This
transistor is not connected internally so that different circuit configurations are possible (see next
section). In order to guarantee correct functionality, the voltage on the output pins has to respect the
specifications VR

AOP

and VR

AOM

as indicated in Table 19-4.

sym

description

min

typ

max

unit

Note

gain

gain at DC

GBW

gain bandwidth product

100

4500

phase margin

resistive

load

300

100000

capacitive

load

CMR

common mode input range

VSS

VBAT

AOM

DAB_AOM voltage range

VSS+0.2

DAB_AOP-0.2 V

AOP

DAB_AOP voltage range

VSS+2.3

VBAT

off

offset

noise

integrated input noise

100

Vrm

source

max source current

PSRR power supply rejection ratio

bias

quiescent bias current

off

current

0.1

1. For all possible combinations of resistive load and capacitive load.
2. At

DC.

Table 19-4. Amplifier specification.

19-4

D0304-40

Datasheet
XE88LC05/05A

19.6 Application

examples

19.6.1

Voltage controlled sensor bias

Figure 19-2 shows the basic connectivity to have a voltage controlled sensor bias. The D/A will
generate a voltage between vrep and vrefn proportional to the input code. The amplifier will copy the
D/A voltage to the sensor. The D/A code can be used to do a software temperature calibration of the
sensor for instance.

Filter capacitors can be added in parallel with the sensor reference and signal, on V

refp

, V

refn

and

DAB_OUT.

The voltages V

refp

and V

refn

can be filtered before being connected to the D/A reference inputs. The

reference voltages can be connected directly to VBAT and VSS for simplicity. They can also be
connected to VBAT and VSS through a low pass filter that rejects the high frequency supply noise.
Finally, in most cases, the voltage range of interest for the voltage V

sensor

on the sensor is only a

fraction of the supply voltage. By generating V

refp

and V

refn

equal to the limits of the voltage range of

interest, the resolution of the D/A can be increased. Example: if a supply of 5V is used and the
reference voltage is equal to the supply, the D/A can generate a sensor voltage between 0V and 5V in
steps of about 5V/25520mV. If the sensor voltage is always to be between 3V and 4V, and by
connecting V

refn

=3V and V

refp

=4V, the sensor voltage is adjustable between 3V and 4V with steps of

about 1V/2554mV.

XE88LCxx

DAB_R_P

DAB_R_M

DAB_OUT

DAB_AIM

DAB_AOP

DAB_AOM

DAB_AIP

amp

signal

reference

VBAT

VSS

sensor

refp

refn

Figure 19-2. Voltage controlled bridge bias principle.

Note that the voltage on the sensor can not be higher than VBAT-0.2V in the example of Figure 19-2
(specification VR

AOM

in Table 19-4).

19-5

D0304-40

Datasheet
XE88LC05/05A

19.6.2

Current controlled sensor bias

Figure 19-3 shows the principle of a current controlled sensor bias schematic. In this case, the
amplifier forces the voltage V

to be equal to the D/A output voltage V

D/A

. The current I

sensor

through

the sensor is given by:

sense

refn

refp

sense

refp

sense

refp

sensor

code

)

255

(

)

(

The voltage V

sensor

can be calculated as a function of the current I

sensor

and the sensor impedance.

Note that the voltage V

>VSS+2.3V and V

-V

sensor

>0.2V (VR

AOP

and VR

AOM

specifications in Table

19-4) to guarantee correct functionality of this schematic.

Choosing the V

refp

equal to the supply voltage or close to the supply voltage in order to have the

highest possible voltage on the sensor is recommended. From the equation, it can be seen that the
sensor current step per LSB can be made smaller by reducing the voltage between V

refp

and V

refn

by increasing the sense resistor value.

As for the voltage controlled sensor bias, capacitors can be added on several nodes to filter out the
noise.

XE88LCxx

DAB_R_P

DAB_R_M

DAB_OUT

DAB_AIP

DAB_AOP

DAB_AOM

DAB_AIM

amp

signal

reference

refp

refn

sense

sensor

D/A

VSS

Figure 19-3. Current controlled bridge bias

In Figure 19-4, the sense resistor is inserted between the negative reference voltage and the sensor.
This schematic has the same principle as above, but it is easier to respect the limits on VR

AOP

when

VBAT is low. The sensor current is now:

sense

refn

refp

sense

refn

sense

refn

sensor

code

)

255

(

)

(

20-2

D0304-40

Datasheet
XE88LC05/05A

20.1 Features

4 x 8-bits timer/counter modules or 2 x 16-bits timers/counter modules

Each with 4 possible clock sources

Up/down counter modes

Interrupt and event generation

Capture function (internal or external source)

Rising, falling or both edge of capture signal

PA[3:0] can be used as clock inputs (debounced or direct)

2 x 8 bits PWM or 2 x 16 bits PWM

PWM resolution of 8, 10, 12, 14 or 16 bits

Complex mode combinations are possible between counter, capture and PWM modes

20.2 Overview

CounterA and CounterB are 8-bit counters and can be combined to form a 16-bit counter. CounterC
and CounterD exhibit the same features.

The counters can also be used to generate two PWM outputs on PB[0] and PB[1]. In PWM mode one
can generate PWM functions with 8, 10, 12, 14 or 16 bit wide counters.

The counters A and B can be captured by events on an internal or an external signal. The capture can
be performed on both 8-bit counters running individually on two different clock sources or on both
counters chained to form a 16-bit counter. In any case, the same capture signal is used for both
counters.

When the counters A and B are not chained, they can be used in several configurations: A and B as
counters, A and B as captured counters, A as PWM and B as counter, A as PWM and B as captured
counter.

When the counters C and D are not chained, they can be used either both as counters or counter C
as PWM and counter D as counter.

20.3 Register map

Bit

RegCntA

reset

function

7-0 CounterA r

xxxxxxxx

8-bits counter value

7-0 CounterA w

xxxxxxxx 8-bits

comparison value

Table 20-1. RegCntA

bit

RegCntB

reset

function

7-0 CounterB r

xxxxxxxx

8-bits counter value

7-0 CounterB w

xxxxxxxx 8-bits

comparison value

Table 20-2. RegCntB

Note: When writing to RegCntA or RegCntB, the processor writes the counter comparison values.
When reading these locations, the processor reads back either the actual counter value or the last
captured value if the capture mode is active.

bit

RegCntC

reset

function

7-0 CounterC r

xxxxxxxx

8-bits counter value

7-0 CounterC w

xxxxxxxx 8-bits

comparison value

Table 20-3. RegCntC

20-3

D0304-40

Datasheet
XE88LC05/05A

bit

RegCntD

reset

function

7-0 CounterD r

xxxxxxxx

8-bits counter value

7-0 CounterD w

xxxxxxxx 8-bits

comparison value

Table 20-4. RegCntD

Note: When writing RegCntC or RegCntD, the processor writes the counter comparison values.
When reading these locations, the processor reads back the actual counter value.

bit

RegCntCtrlCk

reset

function

7-6

CntDCkSel(1:0)

Counter d clock selection

5-4

CntCCkSel(1:0)

Counter c clock selection

3-2

CntBCkSel(1:0)

Counter b clock selection

1-0

CntACkSel(1:0)

Counter a clock selection

Table 20-5. RegCntCtrlCk

bit

RegCntConfig1

Reset

function

CntDDownUp

Counter d up or down counting (0=down)

CntCDownUp

Counter c up or down counting (0=down)

CntBDownUp

Counter b up or down counting (0=down)

CntADownUp

Counter a up or down counting (0=down)

CascadeCD

Cascade counter c & d (1=cascade)

CascadeAB

Cascade counter a & b (1=cascade)

1 CntPWM1 rw

resetsystem

Activate pwm1 on counter c or c+d (PB(1))

0 CntPWM0 rw

resetsystem

Activate pwm0 on counter a or a+b (PB(0))

Table 20-6. RegCntConfig1

bit

RegCntConfig2

Reset

function

7-6

CapSel(1:0)

00 resetsystem

Capture source selection

5-4

CapFunc(1:0)

00 resetsystem

Capture function

3-2

Pwm1Size(1:0)

Pwm1 size selection

1-0

Pwm0Size(1:0)

Pwm0 size selection

Table 20-7. RegCntConfig2

bit

RegCntOn

Reset

Function

7-4 -- r 0000

Reserved

CntDEnable

0 resetsystem

Enable counter d

CntCEnable

0 resetsystem

Enable counter c

CntBEnable

0 resetsystem

Enable counter b

CntAEnable

0 resetsystem

Enable counter a

Table 20-8. RegCntOn

20.4 Interrupts and events map

Interrupt source

Mapping in the

interrupt manager

Mapping in the event

manager

IrqA RegIrqHigh(4) RegEvn(7)
IrqB RegIrqLow(5) RegEvn(3)

IrqC RegIrqHigh(3) RegEvn(6)
IrqD RegIrqLow(4) RegEvn(2)

Table 20-9. Interrupt and event mapping.

20-4

D0304-40

Datasheet
XE88LC05/05A

20.5 Block

schematic

PB(0)

Capture

ck32k

ck1k

PA(0)

RegCntA (write)

Counter A

PA(2)

RegCntC (write)

Counter C

RegCntD (write)

Counter D

RegCntB (write)

Counter B

PA(1)

PA(3)

ck128

ckrcext/4

ckrcext

ck1k

ck32k

PWM

PB(1)

RegCntA (read)

RegCntB (read)

RegCntC (read)

RegCntD (read)

Figure 20-1: Counters/timers block schematic

20.6

General counter registers operation

Counters are enabled by CntAEnable, CntBEnable, CntCEnable, and CntDEnable in RegCntOn.

To stop the counter X, CntXEnable must be reset. To start the counter X, CntXEnable must be set.
When counters are cascaded, CntAEnable and CntCEnable also control respectively the counters B
and D.

In the control registers, all registers must be written in this order: RegCntCtrlCk, RegCntConfig1,
RegCntConfig2 and all RegCntX because several bits have no default values at reset.

All counters have a corresponding 8-bit read/write register: RegCntA, RegCntB, RegCntC, and
RegCntD. When read, these registers contain the counter value (or the captured counter value).
When written, they modify the counter comparison values.

For a correct acquisition of the counter value, use one of the three following methods:

1) Stop the concerned counter, perform the read operation and restart the counter. While

stopped, the counter content is frozen and the counter does not take into account the clock
edges delivered on the external pin.

20-5

D0304-40

Datasheet
XE88LC05/05A

2) For slow operating counters (typically at least 8 times slower than the CPU clock),

oversample the counter content and perform a majority operation on the consecutive read
results to select the correct actual content of the counter.

3) Use the capture mechanism.

When a value is written into the counter register while the counter is in counter mode, both the
comparison value is updated and the counter value is modified. In upcount mode, the register value is
reset to zero. In downcount mode, the comparison value is loaded into the counter. Due to the
synchronization mechanism between the processor clock domain and the external clock source
domain, this modification of the counter value can be postponed until the counter is enabled and it
receives it's first valid clock edge.

In the PWM mode, the counter value is not modified by the write operation in the counter register.
Changing the counter mode, does not update the counter value (no load in downcount mode).

20.7 Clock

selection

The clock source for each counter can be individually selected by writing the appropriate value in the
register RegCntCtrlCk.

Table 20-10 gives the correspondence between the binary codes used for the configuration bits
CntACkSel(1:0), CntBCkSel(1:0), CntCCkSel(1:0) or CntDCkSel(1:0) and the clock source
selected respectively for the counters A, B, C or D.

Clock source for

CntXCkSel(1:0)

CounterA

CounterB

CounterC

CounterD

11 Ck128
10 CkRc/4

Ck1k

01 CkRc

Ck32k

00 PA(0)

PA(1)

PA(2)

PA(3)

Table 20-10: Clock sources for counters A, B, C and D

The CkRc clock is the RC oscillator. The clocks below 32kHz can be derived from the RC oscillator or
the crystal oscillator (see the documentation of the clock block). A separate external clock source can
be delivered on Port A for each individual counter.

The external clock sources can be debounced or not by setting the Port A configuration registers.

The clock source can be changed only when the counter is stopped.

20.8 Counter mode selection

Each counter can work in one of the following modes:

1) Counter, downcount & upcount
2) Captured counter, downcount & upcount (only counters A&B)
3) PWM, downcount

The counters A and B or C and D can be cascaded or not. In cascaded mode, A and C are the LSB
counters while B and D are the MSB counters.

Table 20-11 shows the different operation modes of the counters A and B as a function of the mode
control bits. For all counter modes, the source of the down or upcount selection is given (either the bit

20-6

D0304-40

Datasheet
XE88LC05/05A

CntADownUp or the bit CntBDownUp). Also, the mapping of the interrupt sources IrqA and IrqB and
the PWM output on PB(0) in these different modes is shown.

CascadeAB

CountPWM0

CapFunc(1:0)

Counter A

mode

Counter B

mode

IrqA

source

IrqB

source

PB(0)

function

0 0 00

Counter 8b

Downup: A

Counter 8b

Downup: B

Counter

PB(0)

1 0 00

Counter 16b AB

Downup: A

Counter

- PB(0)

0 1 00

PWM 8b

Down

Counter 8b

Down

Counter

PWM A

1 1 00

PWM 10 16b AB

Down

- -

PWM

0 0

Captured

counter 8b

Downup: A

Captured

counter 8b

Downup: B

Capture

PB(0)

1 0

Captured counter 16b AB

Downup: A

Capture

PB(0)

0 1

PWM 8b

Down

Captured

counter 8b

Downup: B

Must not

be used

Capture

PWM A

Table 20-11: Operating modes of the counters A and B

Table 20-12 shows the different operation modes of the counters C and D as a function of the mode
control bits. For all counter modes, the source of the down or upcount selection is given (either the bit
CntCDownUp or the bit CntDDownUp). The mapping of the interrupt sources IrqC and IrqD and the
PWM output on PB(1) in these different modes is also shown.

The switching between different modes must be done while the concerned counters are stopped.
While switching capture mode on and off, unwanted interrupts can appear on the interrupt channels
concerned by this mode change.

CascadeCD CountPWM1

Counter C

mode

Counter D

mode

IrqC

Source

IrqD

source

PB(1)

function

0 0

Counter 8b
Downup: C

Counter 8b
Downup: D

Counter

PB(1)

1 0

Counter 16b CD

Downup: C

Counter

- PB(1)

0 1

PWM 8b

Down

Counter 8b

Down

- Counter

PWM C

1 1

PWM 10 16b CD

Down

- -

PWM

Table 20-12: Operating modes of the counters C and D

20.9 Counter / Timer mode

The counters in counter / timer mode are generally used to generate interrupts after a predefined
number of clock periods applied on the counter clock input.

Each counter can be set individually either in upcount mode by setting CntXDownUp in the register
RegCntConfig1 or in downcount mode by resetting this bit. Counters A and B can be cascaded to

20-7

D0304-40

Datasheet
XE88LC05/05A

behave as a 16 bit counter by setting CascadeAB in the RegCntConfig1 register. Counters C and D
can be cascaded by setting CascadeCD. When cascaded, the up/down count modes of the counters
B and D are defined respectively by the up/down count modes set for the counters A and C.

When in upcount mode, the counter will start incrementing from zero up to the target value which has
been written in the corresponding RegCntX register(s). When the counter content is equal to the
target value, an interrupt is generated at the next falling edge of counter clock. Then the counter is
loaded again with the zero value at the next rising edge of counter clock (Figure 20-2).

When in downcount mode, the counter will start decrementing from the initial load value which has
been written in the corresponding RegCntX register(s) down to the zero value. Once the counter
content is equal to zero, an interrupt is generated at the next falling edge of counter clock. Then the
counter is loaded again with the load value at the next rising edge of counter clock (Figure 20-2).

Be careful to select the counter mode (no capture, not PWM, specify cascaded or not and up or down
counting mode) before writing any target or load value to the RegCntX register(s). This ensures that
the counter will start from the correct initial value. When counters are cascaded, both counter
registers must be written to ensure that both cascaded counters will start from the correct initial
values.

The stopping and consecutive starting of a counter in counter mode without a target or load value
write operation in between can generate an interrupt if this counter has been stopped at the zero
value (downcount) or at it's target value (upcount). This interrupt is additional to the interrupt which
has already been generated when the counter reached the zero or the target value.

down counting

clock counter X

RegcntX_r

RegCntX_w

write RegCntX

CntXDownUp

IrqX

CntXEnable

up counting

clock counter X

RegCntX_r

RegCntX_w

write RegCntX

CntXDownUp

IrqX

CntXEnable

Figure 20-2. Up and down count interrupt generation.

20-8

D0304-40

Datasheet
XE88LC05/05A

20.10 PWM mode

The counters can generate PWM signals (Pulse Width Modulation) on the Port B outputs PB(0) and
PB(1).

The PWM mode is selected by setting CntPWM1 and CntPWM0 in the RegCntConfig1 register. See
Table 20-11 and Table 20-12 for an exact description of how the setting of CntPWM1 and CntPWM0
affects the operating mode of the counters A, B, C and D according to the other configuration settings.

When CntPWM0 is enabled, the PWMA or PWMAB output value overrides the value set in bit 0 of
RegPBOut in the Port B peripheral. When CntPWM1 is enabled, the PWMC or PWMCD output value
overrides the value set in bit 1 of RegPBOut. The corresponding ports (0 and/or 1) of Port B must be
set in digital mode and as output and either open drain or not and pull up or not through a proper
setting of the control registers of the Port B.

Counters in PWM mode always count down, the CntXDownUp bit setting must be reset. No
interrupts and events are generated by the counters which are in PWM mode. Counters do count
circularly: they restart at the maximal value (either 0xFF when not cascaded or 0xFFFF when
cascaded) when respectively an underflow condition occurs in the counting.

The internal PWM signals are low as long as the counter contents are higher than the PWM code
values written in the RegCntX registers. They are high when the counter contents are smaller or
equal to these PWM code values.

The PWM resolution is always 8 bits when the counters used for the PWM signal generation are not
cascaded. PWM0Size(1:0) and PWM1Size(1:0) in the RegCntConfig2 register are used to set the
PWM resolution for the counters A and B or C and D respectively when they are in cascaded mode.
The different possible resolutions in cascaded mode are shown in Table 20-13. Choosing a 16 bit
PWM code higher than the maximum value that can be represented by the number of bits chosen for
the resolution, results in a PWM output which is always tied to 1.

PwmXsize(1:0)

Resolution

11 16

bits

10 14

bits

01 12

bits

00 10

bits

Table 20-13: Resolution selection in cascaded PWM mode

Small PWM code

Large PWM code

per

hlarge

llarge

hsmall

lsmall

Figure 20-3: PWM modulation examples

The period of the PWM signal is given by the formula:

20-9

D0304-40

Datasheet
XE88LC05/05A

ckcnt

resolution

Tper

The duty cycle ratio DCR of the PWM signal is defined as:

Tper

DCR

DCR can be selected between 0 % and

100

resolution

DCR in % in function of the RegCntX content(s) is given by the relation:

resolution

DCR

RegCntX

100

20.11 Capture function

The 16-bit capture register is provided to facilitate frequency measurements. It provides a safe
reading mechanism for the counters A and B when they are running. When the capture function is
active, the processor does not read anymore the counters A and B directly, but instead reads shadow
registers located in the capture block. An interrupt is generated after a capture condition has been
met when the shadow register content is updated. The capture condition is user defined by selecting
either internal capture signal sources derived from the prescaler or from the external PA(2) or PA(3)
ports. Both counters use the same capture condition.

When the capture function is active, the A and B counters must be written with the value 0xFF and
can either upcount or downcount. They do count circularly: they restart at zero or at the maximal value
(either 0xFF when not cascaded or 0xFFFF when cascaded) when respectively an overflow or an
underflow condition occurs in the counting.

CapFunc(1:0) in register RegCntConfig2 determines if the capture function is enabled or not and
selects which edges of the capture signal source are valid for the capture operation. The source of the
capture signal can be selected by setting CapSel(1:0) in the RegCntConfig2 register. For all
sources, rising, falling or both edge sensitivity can be selected. Table 20-14 shows the capture
condition as a function of the setting of these configuration bits.

CapSel(1:0) Selected capture signal CapFunc

Selected condition

Capture condition

11 1

00
01
10
11

Capture disabled
Rising edge
Falling edge
Both edges

-
1 K rising edge
1 K falling edge
1 K both edges

10 32

00
01
10
11

Capture disabled
Rising edge
Falling edge
Both edges

-
32 K rising edge
32 K falling edge
32 K both edges

01 PA3

00
01
10
11

Capture disabled
Rising edge
Falling edge
Both edges

-
PA3 rising edge
PA3 falling edge
PA3 both edges

00 PA2

00
01
10
11

Capture disabled
Rising edge
Falling edge
Both edges

-
PA2 rising edge
PA2 falling edge
PA2 both edges

Table 20-14: Capture condition selection

21-2

D0304-40

Datasheet
XE88LC05/05A

21.1 Features

Can be switched off, on or simultaneously with CPU activities

Generates an interrupt if power supply is below a pre-determined level

21.2 Overview

The Voltage Level Detector monitors the state of the system battery. It returns a logical high value (an
interrupt) in the status register if the supplied voltage drops below the user defined level (Vsb).

21.3 Register map

There are two registers in the VLD, namely RegVldCtrl and RegVldStat. Table 221-1 shows the
mapping of control bits and functionality of RegVldCtrl while Table 221-2 describes that for
RegVldStat.

pos.

RegVldCtrl

reset

function

7-4 --

r 0000

reserved

VldRange

r w

0 resetsystem

VLD detection voltage range for VldTune = "011":
0 : 1.3V
1 : 2.55V

2-0 VldTune[2:0]

000
resetsystem

VLD tuning:
000 : +19 %
111 : -18 %

Table 221-1: RegVldCtrl

pos.

RegVldStat

reset

function

7-3 --

r 00000

reserved

VldResult

0 resetsystem is 1 when battery voltage is below the detection

voltage

VldValid

0 resetsystem

Indicates when VldResult can be read

VldEn

r w

0 resetsystem

VLD enable

Table 221-2: RegVldStat

21.4 Interrupt map

interrupt source

mapping in the interrupt manager

IrqVld RegIrqMid(2)

Table 221-3: Interrupt map

21.5 VLD operation

The VLD is controlled by VldRange, VldTune and VldEn. VldRange selects the voltage range to be
detected, while VldTune is used to fine-tune this voltage level in 8 steps. VldEn is used to enable
(disable) the VLD with a 1(0) value respectively.

Disabled, the block will dissipate no power.

21-3

D0304-40

Datasheet
XE88LC05/05A

symbol

description

min

typ

max

unit

comments

trimming values:

Note 1

VldRange VldTune

1.53

000

1.44

001

1.36

010

1.29

011

1.22

100

1.16

101

1.11

110

1.06

111

3.06

000

2.88

001

2.72

010

2.57

011

2.44

100

2.33

101

2.22

110

Vth Threshold

voltage

2.13

111

EOM

duration of

measurement

2.0

2.5

Note

Minimum pulse width

detected

875

1350

Note

Table 221-4: Voltage level detector operation

Note 1: absolute precision of the threshold voltage is

10%.

Note 2: this timing is respected in case the internal RC or crystal oscillators are enabled

To start the voltage level detection, the user sets bit VldEn. The measurement is started.

After 2ms, the bit VldValid is set to indicate that the measurement results are valid. From that time
on, as long as the VLD is enabled, a maskable interrupt request is sent if the voltage level falls below
the threshold. One can also poll the VLD and monitor the actual measurement result by reading the
VldResult bit of the RegVldStat. This result is only valid as long as the VldValid bit is `1'.

An interrupt is generated on each rising edge of VldResult.

22-2

D0304-40

Datasheet
XE88LC05/05A

22.1 QFP type package

The QFP package dimensions are given in Figure 22-1 and Table 22-1. The dimensions conform to
JEDEC MS-026 Rev. C.

Figure 22-1. QFP type package

package

LQFP-64

10.0 12.0 1.4 0.10 0.22 0.5

Table 22-1. QFP package dimensions

XEMICS 2003
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Document Outline

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Document Outline

ÐÐ»ÐµÐºÑ‚Ñ€Ð¾Ð½Ð½Ñ‹Ð¹ ÐºÐ¾Ð¼Ð¿Ð¾Ð½ÐµÐ½Ñ‚: XE88LC05ME027