Can bus – Eurotech Appliances ZEUS PXA270 User Manual

Page 57

ZEUS Technical Manual

Detailed hardware description

CAN bus

A Microchip MCP2515 CAN 2.0B protocol compatible controller and MCP2551

transceiver are used on the ZEUS to provide Controller Area Network (CAN) bus

connectivity. CAN is a high-integrity serial data communications bus for real-time

applications. It operates at data rates of up to 1 Mbit/s and has excellent error

detection capabilities. A 16MHz clock is supplied to the CAN controller.

The MCP2515 controller connects to the SPI serial interface of the PXA270 processor.

A MCP2551 transceiver is opto-isolated from the rest of the circuit (3.75kV isolation

voltage), but an external isolated 5V supply needs to be provided to supply the

transceiver and the opto-isolators. Alternatively, non-isolated operation is available

through a factory fit option. Contact

(see page

details.

The CAN bus interface is broken out to the header J17. For connector details see the

Jumpers JP5, JP6 can be used to connect 62Ω termination resistors when the ZEUS is

at the end of the network. Split termination concept is used on ZEUS (see figure

below). For details see the section

JP5

JP6

62 Ohm

CAN_H

CAN_L

CAN Transceiver

Split

Termination