I am having a similar issue with the Jetson Nano Nx compared to:
- Jetson AGX Xavier, something wrong when testing CAN in normal mode( non-loopback )
- CAN Connection problems
In my case, we hook a CAN transceiver up to the J17 pin set on the board and run the following
#!/bin/bash sudo busybox devmem 0x0c303020 w 0x458 sudo busybox devmem 0x0c303018 w 0x400 sudo modprobe can sudo modprobe can_raw sudo modprobe mttcan # Does not work without "loopback on" unknown why sudo ip link set can0 type can bitrate 1000000 loopback on sudo ip link set up can0 ip -s -d link show can0 candump can0 & cansend can0 123#abcdabcd
This successfully transmits the CAN message over the bus and is received by another node on the bus. We also see the message via
candump. We also see the message on the Tx side and bus side via a logic analyzer.
In this configuration we receive loopback messages even without the transceiver or shorting the Tx and Rx pins. Why is that?
Nothing is transmitted on the Tx pins (or the bus) without ‘loopback on’ in the above script.
loopback on required to transmit CAN messages?