There is CBB serial board may you need

https://docs.google.com/document/d/1sgurQ-7gLyn7g-Kg983NRM0aDkYEqHqy9dmrieX_RUM/edit#

I do the test with a simple module

https://github.com/digitalbond/canbus-beaglebone

That may help you with set up CAN bus with Beaglebone Black

The import things that you should disable HDMI

add

capemgr.disable_partno=BB-BONELT-HDMI,BB-BONELT-HDMIN

to

/boot/uEnv.txt