COM20022
10 Mbps ARCNET (ANSI 878.1) Controller with 2Kx8
On-Board RAM
FEATURES
New Features
-
Data Rates up to 10 Mbps
-
Selectable 8/16 Bit Wide Bus With Data
Swapper
-
Programmable DMA Channel
-
Programmable Reconfiguration Times
-
48 Pin TQFP Package
Ideal for Industrial/Factory/Building
Automation and Transportation
Applications
Deterministic, (ANSI 878.1), Token Passing
ARCNET Protocol
Minimal Microcontroller and Media
Interface Logic Required
Flexible Interface For Use With All
Microcontrollers or Microprocessors
Automatically Detects Type of
Microcontroller Interface
2Kx8 On-Chip Dual Port RAM
Command Chaining for Packet Queuing
Sequential Access to Internal RAM
Software Programmable Node ID
Eight, 256 Byte Pages Allow Four Pages TX
and RX Plus Scratch-Pad Memory
Next ID Readable
Internal Clock Scaler and Clock Multiplier for
Adjusting Network Speed
Operating Temperature Range of -40
o
C to
+85
o
C
Self-Reconfiguration Protocol
Supports up to 255 Nodes
Supports Various Network Topologies (Star,
Tree, Bus...)
CMOS, Single +5V Supply
Duplicate Node ID Detection
Powerful Diagnostics
Receive All Packets Mode
Flexible Media Interface:
-
Traditional Hybrid Interface For Long
Distances up to Four Miles at 2.5Mbps
-
RS485 Differential Driver Interface
For Low Cost, Low Power, High
Reliability
2
GENERAL DESCRIPTION
SMSC's COM20022 is a member of the family of Embedded ARCNET Controllers from Standard
Microsystems Corporation. The device is a general purpose communications controller for networking
microcontrollers and intelligent peripherals in industrial, automotive, and embedded control environments
using an ARCNET
protocol engine. The small 48 pin package, flexible microcontroller and media
interfaces, eight- page message support, and extended temperature range of the COM20022 make it the
only true network controller optimized for use in industrial, embedded, and automotive applications.
Using an ARCNET protocol engine is the ideal solution for embedded control applications because it
provides a deterministic token-passing protocol, a highly reliable and proven networking scheme, and a
data rate of up to 10 Mbps when using the COM20022. A token-passing protocol provides predictable
response times because each network event occurs within a predetermined time interval, based upon the
number of nodes on the network. The deterministic nature of ARCNET is essential in real time
applications. The integration of the 2Kx8 RAM buffer on-chip, the Command Chaining feature, the 10
Mbpsmaximum data rate, and the internal diagnostics make the COM20022 the highest performance
embedded communications device available. With only one COM20022 and one microcontroller, a
complete communications node may be implemented.
3
TABLE OF CONTENTS
FEATURES.............................................................................................................................................1
GENERAL DESCRIPTION.....................................................................................................................2
PIN CONFIGURATION...........................................................................................................................5
DESCRIPTION OF PIN FUNCTIONS ....................................................................................................6
PROTOCOL DESCRIPTION ..................................................................................................................9
NETWORK PROTOCOL....................................................................................................................9
DATA RATES ....................................................................................................................................9
NETWORK RECONFIGURATION...................................................................................................10
BROADCAST MESSAGES..............................................................................................................11
EXTENDED TIMEOUT FUNCTION.................................................................................................11
LINE PROTOCOL............................................................................................................................11
SYSTEM DESCRIPTION......................................................................................................................14
MICROCONTROLLER INTERFACE ...............................................................................................14
TRANSMISSION MEDIA INTERFACE ............................................................................................23
FUNCTIONAL DESCRIPTION .............................................................................................................28
MICROSEQUENCER ......................................................................................................................28
INTERNAL REGISTERS..................................................................................................................31
INTERNAL RAM ..............................................................................................................................49
COMMAND CHAINING....................................................................................................................54
INITIALIZATION SEQUENCE..........................................................................................................56
IMPROVED DIAGNOSTICS ............................................................................................................57
OPERATIONAL DESCRIPTION ..........................................................................................................59
MAXIMUM GUARANTEED RATINGS*............................................................................................59
DC ELECTRICAL CHARACTERISTICS ..........................................................................................59
TIMING DIAGRAMS.............................................................................................................................62
APPENDIX A ........................................................................................................................................82
APPENDIX B: EXAMPLE OF INTERFACE CIRCUIT DIAGRAM TO ISA BUS..................................86
COM20022, FUNCTIONAL REV. B ANOMALY...................................................................................87
4
For more details on the ARCNET protocol engine and traditional dipulse signaling schemes, please
refer to the ARCNET Local Area Network Standard, or the ARCNET Designer's Handbook, available
from Datapoint Corporation.
5
PIN CONFIGURATION
COM20022
48 Pin TQFP
1
2
3
4
5
6
7
8
9
10
11
12
AD0
AD1
D10
AD2
D11
D3
VDD
D4
D5
VSS
D6
VSS
13
14
15
16
17
18
19
20
21
22
23
24
D7
D12
D13
D14
D15
N/C
VDD
XT
AL1
XT
AL2
nPULSE1
VSS
VS
S
25
36
35
34
33
32
31
30
29
28
27
26
nPULSE2
BUSTMG
N/C
RXIN
nTXEN
nRESET
VDD
DREQ
nINTR
nDACK
nCS
VSS
37
38
39
40
41
42
43
44
45
46
47
48
TC
D9
D8
A2/A
LE
A1
A0/nM
U
X
VD
D
nIO
C
S16
nREFE
X
nRD
/
nDS
nW
R
/
DIR
VSS
Ordering Information:
PACKAGE TYPE: TQFP
TEMP RANGE: (Blank) = Commercial: 0C to +70C
I = Industrial: -40C to +85C
DEVICE TYPE: 20022 = Universal Local Area Network Controller
(with 2K x 8 RAM)
COM20022
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