ATSAME51 Sending invalid ACK on canbus

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We have an issue with a board using an ATSAME51 causing disruption on our CAN bus.
The ATSAME51 sends erroneous acknowledgements that cause re-transmission of messages sent from other devices on the network. We are using an external 24MHz oscillator with the PLL to run MCLK at 96MHz. Our can bus is running at 1Mbit/s. The bit timing is set to prescaler 2, prop-seg 4, phase-seg1 37, phase-seg2 6.

Here you can see the CAN_RX line from a CAN transceiver on the bus showing the ATSAME51 sending an extended ACK pulse followed by a normal ACK on the next frame. The ATSAME51 does not do this for every frame sent, only some portion of CAN frames sent on the network get these extended ACKs.

 

 

This is the CAN_TX line for the same 2 frames from the ATSAME51:

 

Any suggestions on what may be causing the issue?

Thank you.

 

 

 

Last Edited: Tue. Apr 26, 2022 - 12:49 PM
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I have resolved this issue by adjusting the CAN sample point from 87.5% to 75%