Basic CAN bus transmit

dteal · ‎2015-02-08

Posted on February 09, 2015 at 00:59

I am new to the CAN bus and have spent the last few days looking over code examples and searching the web for tips and I'm using the STM32303C-EVAL board.

I'm just trying to get transmit to work, so my question is this: with nothing connected on the CAN bus DB9, shouldn't I see at least some o-scope activity on the CANH or CANL signals on the bus side of the transceiver? I also have a Microchip CAN bus analyzer that can receive as well as transmit.

Thanks,

DT

#can

dteal · ‎2015-02-09

Posted on February 09, 2015 at 23:38

Problem solved and the answer is yes, you can see pulses on the CAN bus with absolutely nothing else connected. The problem was that I was using GPIO_AF_9 instead of GPIO_AF_7. I can transmit and receive (using the Microchip bus analyzer in transmit mode) at 1 Mbps.