Debugging a LPC23XX based CAN bus sniffer
I've worked with the Microchip CAN controller with SPI bus interface, MCP2515. One of the most difficult parts of setting up CAN is making sure that all the baud rate registers are set properly for all of devices on the bus. I'm not sure if you have access to the registers on the sending device, but being able to read the exact baud rate register values from the sender may give you an idea as to which register you have configured incorrectly. Also knowing the type of error if any is being detected by the sender may help you solve your CAN bus problem.

Microchip has an application note, AN754, that provides a guide to setting the CAN bus timing. It's not specific to Microchip. There are a few basic timing parameters you must set properly in order for the CAN bus communication to work. They are:


Tq = Time Quanta
Nominal Bit Time
Synchronization segment width
Propagation segment width
Phase segment 1 width
Phase segment 2 width


Make sure these values all match in your sender and receiver.