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Acknowledgement Error in CAN Communication

Associate II

Hello there,

I am newbie in CAN communication. Although there is no problem in loopback mode, I get acknowledgment error in normal mode. For this reason, the tx message I sent continues to be sent because it was not ACKed, and after a while, all mailboxes fill up and the HAL_ADDTX function returns HAL_CAN_ERROR_PARAM. When I check the LEC register, I get Acknowledgment Error. I shared the diagram I used and my codes. You can review the main.c msp.c and it.c files on the Github link. The reason I don't use 120 ohms between CANH and CANL is because it's in my cjmcu230(with SN65HVD230) transciever module. I am using the same code on two STM32F429 boards. Thank you in advance for your help.

Github Link:

My Diagram:


CANTx logic signals in my logic analyzer(you can see it keep repeats the same msg):


Associate III

Hi SUrte.1

at first glance it looks like a hardware I assume with CAN:RX you mean the R output of the CAN Transceiver chips. Did you measure the RX-line coming from the N2 reveiver chip? It should be the same signal as the one you are sending out and viewing at CH1.

I assume there might be a disturbed outpu, Since you are operating the CAN trnasceivers at the very lower end of the allowed power supply.

Best regards


ST Employee


Check all your wiring continuity .. If it's ok, I doubt there is an issue with the module. Someone has raised an issue with CJMCU230 module with a counterfeit SN65HVD230 part. So check this video out:

To give better visibility on the answered topics, please click on "Accept as Solution" on the reply which solved your issue or answered your question.

First of all, thank you very much for your answer.

The CH-1 signal is the CANTx signal found in N-1. The CH-2 signal is the CANTx signal in N-2. My purpose in these connections was to see that after the Tx signal I sent from N-1, the necessary ack signal came from the Tx signal in N-2. However, as you can see that the tx message is constantly repeated because the necessary ack signal does not come from N-2. And I also thought about the problem that might be caused by using 3V, but this is the maximum voltage I can get from the stm32f429 pins and I am afraid of that how can I increase it or if I increase it, I can disrupt the Rx Tx signals from PA11 and PA12. But right now I suspect most of my transcievers are corrupt.


Thank you very much for your reply. I was also suspecting the transceiver. Do you have a suggestion for a transceiver module that can work using the same method?

Can you have any suggestion for increasing pin voltages without disrupt ?

And I guess I can work with 3v max. Do you have any suggestions for a suitable module for it?

Please help me to understand your question.

From your picture is assumed you are running both STM32 and CAN-Transsceiver from a 3V supply instead of the more common 3.3V supply.

The signal level at the pins is of course lower and actually in the range of 3V.

I think I got you wrong, but I understood your answer that you are using a 3V power supply for the CAN transceiver because the output signal from the STM32 is at 3V?

Or are you using a 3.3V power supply for all the devices and I simply got you wrong, in which case my thoughts about the low supply for the the CAN transceivers are wrong.

At the moment for me the most likely cause of your issue are fake CAN transceivers.

But that can easily be tested by measuring the outuput CAN_RX at N-2.



Unfortunately, when I examined the CANTx side of the N-2 with a logic analyzer, I could not see a signal. Does this indicate a problem with the transciever?

Sorry i meant CANRx instead of CANTx