Author Topic: STM32 CAN bus Bus-off recovery question  (Read 888 times)

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Offline Red_MicroTopic starter

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STM32 CAN bus Bus-off recovery question
« on: April 12, 2023, 11:29:01 pm »
Using STM32F4 as example, the reference manual says:

Quote
The Bus-Off state is reached when TEC is greater than 255, this state is indicated by BOFF
bit in CAN_ESR register. In Bus-Off state, the bxCAN is no longer able to transmit and
receive messages.
Depending on the ABOM bit in the CAN_MCR register bxCAN will recover from Bus-Off
(become error active again) either automatically or on software request. But in both cases
the bxCAN has to wait at least for the recovery sequence specified in the CAN standard
(128 occurrences of 11 consecutive recessive bits monitored on CANRX).

So my question is.. if there's already activity on the bus due to other nodes, will the bus-off node ever see those 11 consecutive recessive bits needed to synchronize to the bus?
 

Offline langwadt

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Re: STM32 CAN bus Bus-off recovery question
« Reply #1 on: April 13, 2023, 12:16:05 am »
https://en.wikipedia.org/wiki/CAN_bus#Base_frame_format

ACK delimiter, End-of-frame (EOF),Inter-frame spacing (IFS)    adds up to eleven recessive bits
 
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