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we are testing out integrating an AIO-3568j board. We have a CAN with a 500,000bps bus, but when we attempt to connect this board to our bus we are receiving packets but almost all of them are being received as errors (we only need to receive messages). We are also testing a Debix SOM A + IO board, when we connect this Debix board it is working correctly with no errors, we are connecting both boards to our bus in the same way with the same cables.

We noted that both boards seem to have a 120 olm resistor, so this shouldnt be the problem.

To setup the CAN bus in Ubuntu we run these commands 'ip link set can0 type can bitrate 500000' 'ip link set can0 up' we also tried setting the qdisc to default as we noticed the Debix board uses the default, while this firefly defaults to fq_codel. 'tc qdisc replace dev can0 root pfifo_fast' We tested both can0 and can1 with the same settings and received the same results.

I will attach a screen shot showing the ifconfig read out. It shows both can bus interfaces with lots of errors but note they weren’t connected at the same time, the interfaces were tested separately.

Do you have any ideas on what the issue could be? I know im being specific with the hardware we are using but any general ideas on things to check or try is appreciated. Thanks!

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Dash100555
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  • Can you be a bit more specific about the errors? Also, try observing the actual signals with a logic analyzer – Marcus Müller Jan 27 '23 at 08:51
  • @MarcusMüller the errors im talking about are just the 'RX errors' in the ifconfig command, is it possible to see the specifics of these errors? – Dash100555 Jan 27 '23 at 09:43
  • Actually a surprisingly good question. Things I'd try is first check whether your `can0`/`can1` can be supervised using `wireshark`, and check whether you see something suspicious. – Marcus Müller Jan 27 '23 at 09:55
  • oh and try setting a device address just for the heck of it and see whether that helps. – Marcus Müller Jan 27 '23 at 09:55
  • You'll be able to see error frames with a scope, They look like pulses high or low of 6 times your bit length. In this case around 12us long. – Lundin Jan 30 '23 at 09:52

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