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2.15 CAN Interface
*SOM-5992 is not support CAN Interface.
CAN Bus Operation Over SER1 Lines
The SER1_TX and SER1_RX asynchronous serial port lines defined for COM.0 Types 7
may
be used
alternatively to carry CMOS 3.3V logic level CAN (Controller Area Network) bus signals from a COM
Express Module based CAN protocol controller. The CAN bus is an asynchronous, message based
protocol widely used in the automotive and industrial control sectors. It is defined by ISO 11519, ISO
11898, and SAEJ2411. Data rates on a CAN bus
may
be as high as 1 MBit/s, although lower rates in the
range from 10 kBit/s to 125 kBit/s are more common.
Use of the CAN bus in a COM Express system requires a CAN bus transceiver on the Carrier Board to
interface to the CAN physical layer. CAN bus transceivers are available from NXP, Texas Instruments,
Linear Technology, and others.
Data from the COM Express Module based CAN controller to the Carrier Board CAN transceiver is
carried on Module line SER1_TX. Data from the Carrier Board CAN transceiver to the COM Express
Module based CAN controller is carried on Module line SER1_RX. The Carrier Board CAN transceiver
converts the logic level CAN protocol TX and RX signals from the Module into a differential half duplex
line per the CAN specification.
How the SER1 asynchronous lines are shared with CAN bus operation is Advantech specific. Advantech
may
choose to use the SER1 TX and RX lines to support asynchronous serial port operation, or CAN
bus operation, or both, or neither. Module build option(s) or software controlled muxing implementations
may
be used.
Please
contact Advantech for information on the CAN Bus used.
2.15.1 CAN interface Signal Definitions
Table 41
: CAN interface Signal Definitions
Signal
Pin# Description
I/O
Note
CAN_TX
/ SER1_TX
A101 Transmit Line for CAN
Carrier Board:
Check your CAN transceiver application notes.
O CMOS
1
CAN_RX
SER1_RX
A102 Receive Line for CAN
Carrier Board:
Check your CAN transceiver application notes.
I CMOS
1
Note:
1. SOM-5992 is not support CAN Interface.
