CAN is not functional after ACK error

[AGupt.11]

We are using STM32L4A6VGTx MCU. In this for CAN we are receiving error multiple times (ACK error, EPV error, EWG error). Due to this we are not able to transmit and receive on CAN bus. Please let us know how to reset the errors, so that CAN will be functional.

[AvaTar]

> We are using STM32L4A6VGTx MCU.

Don't know that part.

After a certain amount of errors, the CAN bus goes into error-passive mode, and finally in bus-off.

Usually, the CAN peripheral unit resets the enable flag in this case.

Check the respective section of the Reference manual.

[AGupt.11]

Hello AvaTar,

Thanks for the reply.

>Usually, the CAN peripheral unit resets the enable flag in this case.

Could you please let us know detail about these flags?

Problem Detail:

We are trying to send CAN Msg on bus when no other ECU is connected, this gives us ACK error many times. Now we connected PCAN (Other ECU) and We are trying to send CAN msg. The reception is not working even after software reset to CAN.

Thanks,

Anjalee

[AvaTar]

As said - I don't know your specific MCU, and do not have your hardware.

Read the CAN section of the reference manual for your MCU, and the CAN specification, if required.

> Now we connected PCAN (Other ECU) and We are trying to send CAN msg.

I guess you mean the PCAN CAN dongle for PC, which is not an ECU. Does the PC application (PCAN Explorer) say "Bus heavy" or "Bus light" ?

Anyway, even for a short 2-peer bus, you need a proper bus termination resistance (120 Ohm between CANH and CANL). Check for proper connection (CANH -> CANH, CANL -> CANL).

Check the bus signals with a scope, perhaps reduce the baudrate.

[AGupt.11]

>I guess you mean the PCAN CAN dongle for PC, which is not an ECU.

PCAN View is used for simulation of ECU.

>Does the PC application (PCAN Explorer) say "Bus heavy" or "Bus light" ?

It shows "OK" .

We have used proper bus termination resistors (120 ohm) .