Kontron COMe Starterkit Eval T2 - Manual (Page 127)

COM Express Interfaces
2.21. CAN Interface
CAN bus is a vehicle bus standard designed to allow controllers and devices to communicate
with each other without a host computer. CAN bus is a message-based protocol, designed
specifically for automotive applications but now also used in other areas such as industrial
automation and medical equipment.
Development of CAN bus started originally in 1983. The protocol was officially released in 1986
at the Society of Automotive Engineers (SAE) congress in Detroit, Michigan. The first CAN
controller chips, produced by Intel and Philips, came on the market in 1987. In 1991 the CAN 2.0
specification was published.
Since 2008 CAN bus has been mandatory in any US vehicle in the OBD-II car diagnostic port. It
is also used extensively in industrial automation.
2.21.1. Signal Definitions
Table 40: CAN Interface Signal Definition
Signal Pin Description I/O
CAN_TX A101 Transmit Line for CAN (can be shared with SER1 function) O CMOS (protected)
CAN_RX A102 Receive Line for CAN (can be shared with SER1 function) I CMOS (protected)
This signals have been introduced in COM.0 Specification Revision 2.1 optionally for Type 10
and Type 6 Modules. They have been reclaimed from the VCC_12V pool. Therefore protection
on the Module and on the Carrier Board is necessary that accidental exposure to 12V will not
lead to either damaged Modules or Carrier Boards. Please refer to section 2.22.10 'Protecting
COM.0 Pins Reclaimed From the VCC_12V Pool' on page 144 below.
The protection, especially the series diode on the Module reduce the maximum speed on the
CAN interface to about 10 Kbaud.
The CAN port consists of an asynchronous CAN TX line and an RX line from and to the COM
Express Module CAN protocol controller. A Carrier based CAN transceiver is required to realize
a CAN implementation. CAN PHYs are available from Texas Instruments, On Semiconductor,
NXP, Freescale, Microchip and numerous other vendors.
CAN bus on COM Express is an optional interface, which means that the system designer must
verify, if the selected Module supports it.
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