CAN BUS Tx not working in Normal mode

[Touftoufe]

Hello !

Hope you're all doing well.

I have a little problem here, my CAN BUS Tx is not working on "Normal Mode"

• I have a bus with several nodes communicating between them without any problem, so the bus itself is not the problem
• In "Loopback mode" it works well
• In "Normal Mode", the Rx works but the Tx doesn't
• I used an stm32F429 and an stm32F103, and the problem is the same in both MCUs
• I also tried different CAN transceivers, same problem

Any idea why it behaves like this?

Thank you :D

[Tesla DeLorean]

Does it report some error or status that might be helpful in identifying the mode of failure?

Anything that will receiver and acknowledge the specific message ID being transmitted?

Is there a bus analyzer? What doesn't it see/report?

[Touftoufe]

I have a bus analyser to receive and transmit frames and an oscilloscope to monitor the signals.

• In the beginning, I can see that the stm32 tries to send a frame using the scope, the Tx is pulled low then immediately goes high and then nothing. In this case, I get error number 0.
• Then after a fiew secondes, mailboxes end up filled

The reception works fine and the bus analyser doesn't show any error

[Touftoufe · Accepted solution]

In the end it was a voltage level issue with the transceiver standby pin. Every thing works fine now