I use an atmega168 and a MCP2515/2551 to talk CAN, for a car embedded product. They talk via SPI, both chips have a separated 16MHz crystal. The RS slope on the 2551 is 47k.
I sniff the bus in read only mode and can see all kind of messages on some cars (Hyundai Elantra, Pontiac G5, Chevrolet Cobalt, Saturn Vue) but on a few cars (Honda Odyssey, Jeep Patriot) the hardware sees nothing.
I am using the "kreatives-chaos" CAN library with blank filter in sniffing mode, on the car that are working, I can even send obd2 message and get the answer back (like rpm, temperature, etc) and I use filter, it works fine. On the cars that do not work, even if I send a request message to the ECU, I have no message coming from the MCP2515, no interrupt, meaning the 2515 does not see anything. I tried 250k and 500k speed bus.
I know a couple of people here used an AVR with a MCP2515/2551 for car embedded product, did you have problem with some cars? You can send me a PM if you prefer, give hints, discuss, give clues, whatever!
I went through all the library sources, the PDF, etc and everything is setted right, loopback is working fine too. The lib is pretty well written.
It's just that some cars do not work and I don't know why :?:
If someone can help me, thanks in advance!!!