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I have been using a CAN/RS485 Cape for prototyping CAN control of a motor. I am now in the process of bringing up some custom hardware. I have a CAN Transceiver SN65HVD230D on this custom cape that is connected to pins 31 and 32 on P8 - UART5 TX/RX.

I tried simply configuring the pinmux using config-pin however I got two errors:

user@beaglebone:/lib/firmware$ sudo config-pin P8.31 can
P8_31 pinmux file not found!
Invalid mode: can

Is it necessary to create a device tree overlay as this question suggests?

Is it even possible to use these pins for CAN or is CAN only available through DCAN0/1_RX/TX pins?

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  • \$\begingroup\$ I am trying to bring up a cape designed by a contractor \$\endgroup\$
    – Cameron
    Commented Oct 1, 2020 at 20:40
  • \$\begingroup\$ My unconfirmed suspicion would be that this isn't going to easily work, maybe ask them what they were thinking? You could probably white-wire the cape to get signals from different connector pins. \$\endgroup\$
    – Chris Stratton
    Commented Oct 1, 2020 at 20:44
  • \$\begingroup\$ That said you seem to have a bunch of overlapping issues - eg, you have now one but two error messages showing, and the runtime config vs device tree points to the fact that the beaglebone has been around long enough to have multiple conflicting conventions for how software manages hardware; you'll need the one appropriate to your Linux, or a Linux appropriate to the method you want to use. \$\endgroup\$
    – Chris Stratton
    Commented Oct 1, 2020 at 20:45
  • \$\begingroup\$ Gotcha. That's a pretty simple fix. I have been able to config pins P9.24 and P9.26 properly interestingly enough. I'm not sure why pinmuxing isn't working for P8.31/32. \$\endgroup\$
    – Cameron
    Commented Oct 1, 2020 at 20:50
  • \$\begingroup\$ Can you help clarify what the BBB MCU is doing in this case? It looks like it has two DCAN interfaces - is it implementing the "data-link" layer of the OSI model? With SN65HVD as the physical layer? \$\endgroup\$
    – Cameron
    Commented Oct 1, 2020 at 20:51

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