My apologies if this is the wrong stack website for this question.
We plan to use a BeagleBone Black as the control computer for an electric car. The BBB handles, among other things, communicating with the motor controllers over the CAN protocol (using can-utils).
Installation (according to a number of online guides) seemed to be going well (device tree setup, modprobe, etc), with no errors, until we actually plugged into the motor controllers... and nothing happened.
We hooked up an oscilloscope (to both the TX and RX wires on the BBB) and watched the execution of the following commands:
ifconfig can0 down ifconfig can0 up cansend can0 180#1234
which should send data along the bus. The oscilloscope showed the following (RX on top, TX on bottom), every time we executed the commands above.
I suspect this signal we were seeing is some sort of handshake which was not being answered.
(Note that if we tried to run
cansend again, nothing would happen until we ran
After many such execution cycles, interestingly,
ifconfig reported that the RX bytes had been increased, even though nothing had been received, only sent.
A few days later, with an identical setup, the CAN bus is still not working, and we are not seeing the handshake signal on the oscilloscope.
ifconfig reports dropped bytes but little else to help us.
Any ideas on where to go from here, how to debug this issue, etc.?