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CAN bus ACK issue with TJA1042

Question asked by Peter Yu on Dec 6, 2018

Hi all,

 

I got a CAN bus issue on S12 MCU with TJA1042 CAN transceiver.

Node A received message and 'ACK back', but host(S12 + TJA1042) could not detect the ACK.

The result is host continued to re-sent message and then bus heavy.

I found the signal level of ACK(can low to can high) is larger(over 2V) than other CAN bus signal.

Does this cause ACK fail or other error so host re-send message again and again.

By the way, if I add a PCAN tool connect to laptop and open PCAN-view to check data, host would detect the ACK(from PCAN-view??) and would not re-send again. 

The circuit and waveform are below:

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