I want to verify the CAN interfaces on my embedded system. It has two can ports: can0 and can1.
I bring them both up with the following sequence:
# ip link set can0 type can bitrate 1000000 dbitrate 2000000 fd on
# ip link set can0 up
# ip link set can1 type can bitrate 1000000 dbitrate 2000000 fd on
# ip link set can1 up
I hooked them up to each other (CANH<->CANH, CANL<->CANL & GND<->GND) with termination resistors on each side after the trabnsceivers.
Now when I want to send traffic out on can0 and dump rthe incoming traffic on can1.
I started candump -c -a any while I invoke:
# cansend can0 01a#11223344AABBCCDD
But after this, I get a bunch of kernel errors that look like:
[ 1506.337694] rcar_canfd 10050000.can can0: ch erfl 401 txerr 128 rxerr 0
[ 1506.337702] rcar_canfd 10050000.can can0: Bus error
[ 1506.337707] rcar_canfd 10050000.can can0: ACK Error
Appears like 128 stands for CAN_ERROR_PASSIVE_THRESHOLD which indicates that about which I read:
Error Passive: In this state, the CAN node is still able to transmit data, but it now raises 'Passive Error Flags' when detecting errors. Further, the CAN node now has to wait for an extra 8 bits (aka Suspend Transmission Time) in addition to the 3 bit intermission time before it can resume data transmission (to allow other CAN nodes to take control of the bus)
There's nothing showing with candump, though. The above messages show up in dmesg.
But I still can see data on the CAN lines (with a scope).
What do the errors mean, how can I address them and how can I actually see data with candump?
