canbus remote request

[eiten]

Hello everybody,

how is it possible to

1. Send rtr with the current zephyr version? can_frame has not rtr-field anymore
2. Receive rtr and then send the requested data? If you set the rx filter to an ID, rtr will not trigger the callback/message queue.

Thanks, Edi

[henrikbrixandersen]

1. Send rtr with the current zephyr version? can_frame has not rtr-field anymore

You set the CAN_FRAME_RTR flag in flags member in the struct can_frame TX instance.

2. Receive rtr and then send the requested data? If you set the rx filter to an ID, rtr will not trigger the callback/message queue.

You need to enable CONFIG_CAN_ACCEPT_RTR=y to allow incoming RTR frames, add a CAN RX filter for the specific CAN ID and check for the CAN_FRAME_RTR flag in matching RX frames in your callback. If the CAN ID matches and the RTR flag is present, you need to queue up a response TX frame (which can be prepared in advance, if needed).

Hardware support for RTR is very, very different between various CAN controllers (quite a few controllers don't even support RTR and its use is discouraged), making it very difficult to come up with a common Zephyr CAN API abstraction for handling automatic RTR replies.

[eiten]

Hi @henrikbrixandersen

Thank you very much, I was missing the CONFIG_CAN_ACCEPT_RTR=y part! Now everything works as expected.!

Have a nice day!

[henrikbrixandersen]

Hi @henrikbrixandersen

Thank you very much, I was missing the CONFIG_CAN_ACCEPT_RTR=y part! Now everything works as expected.!

Glad you got it to work.

Have a nice day!

Thanks, same to you ☺️