CAN Messages is not Transmitted Unless HW Reset MBD

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CAN Messages is not Transmitted Unless HW Reset MBD

Contributor IV

Dear All,

I have a model that has CAN TX and RX messages on Simulink. I am reading CAN messages on BusMaster program.

- I have one RX ID.

- I have approximately 25 TX ID. 

      * One of them is Echo of RX message. What it receives is sent back.

      *Other 24 are is regular sent messages.


I have some problems and questions regarding with my problems.

My problems are  

1. Can messages are not sent immediately after code has been built and loaded. I have to reset S32K144 DEVKIT with Reset Button on itself. After reset it starts to send again.

2. After I build, reset and get CAN messages, I disconnect BusMaster from CAN line. If disconnection is more than 1 second, which is sample time for our model, CAN does not send TX messages to Busmaster after connecting again.

3. I send 1 TX message with 500ms period and it reflect back to me same message. After do not sending message more than 1 second, and sending again periodically, it does not reflect it back.


What may be problems of my model?

How can I solve that?





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2 Replies

NXP TechSupport
NXP TechSupport



I do not know coding with Simulink. But general, if you see issue with receiving/transmitting I can recommend to check FlexCAN ESR and ECR registers to know if any errors are detected.

If you have a MB prepared for transmission, module is synced to the bus then a message should be sent on first opportunity window on the bus after MB wins internal arbitration. In such case if errors is seen it can point to e.g to wrong CAN bit timing, transceiver issue or similar.


BR, Petr

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Senior Contributor IV


I observe something like you on S32K144 DEVKIT. After powering board on I need to push RESET button, else messages seem not being send via UJA1169 chip. I think it's something with that UJA1169. Attaching different CAN bus driver to non-FD CAN module pins is problem less. In router application non-UJA1169 CAN port is always responsive. UJA1169 port starts working only after pushing RESET button. Perhaps something should be done to SBC initialization code, but since we are not going to use that chip, I had no time to investigate it further.

S32K148 DEVKIT doesn't have this problem, CANFD always responsive out power on.



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