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 Eurotech Technical Support (see page 97) for details.

The CAN bus interface is broken out to the header J17. For connector details see the section J17 – CAN bus, page 87.

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 – CAN bus termination, page 95.

CAN_H

JP5

62 Ohm

Split

Termination

C

62 Ohm

CAN Transceiver

JP6

CAN_L

© 2007 Eurotech Ltd Issue D

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