CAN Bus

The CAN bus signal of PCIe-GL26 is directly from the Jetson Xavier NX module with an additional isolated transceiver. The CAN bus of Jetson Xavier NX is from Bosch Time-Triggered Controller Area Network (M_TTCAN) controller version 3.2.0. It supports CAN 2.0.

System Node

Execute the following script before using the CAN bus on NRU-50. Please double confirm the CAN Bus configuration with other connected CAN devices, especially:

• Bitrate

• Payload bit rate

• Bus error reporting

Initialization Script

modprobe can
modprobe can-raw
modprobe mttcan

sudo ip link set can0 up type can bitrate 500000

If you have initially the CAN bus successfully, you will see can0 in the result of ifconfig, e.g.,

can0: flags=193<UP,RUNNING,NOARP>  mtu 72
        unspec 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00  txqueuelen 10  (UNSPEC)
        RX packets 1118  bytes 8944 (8.9 KB)
        RX errors 1117  dropped 0  overruns 0  frame 0
        TX packets 0  bytes 0 (0.0 B)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
        device interrupt 64

Then you can access the CAN Bus on panel via can0

Pin Definition

Please refer to 10-Pin / 8-Pin Terminal Block.

120 Ohm Termination

Make sure you have enabled the 120 Ohm termination of the two ends of your CAN Bus. PCIe-GL26 has an on-board termination which can be controlled via GPIO. By default, we have enabled the CAN Bus termination in the device tree.

You may enable and disable it by the following commands.

# Enable CAN Bus Termination
sudo echo 264 > /sys/class/gpio/export # CAN0_TERM
sudo echo out > /sys/class/gpio/gpio264/direction
sudo echo 1 > /sys/class/gpio/gpio264/value

# Disable CAN Bus Termination
sudo echo 264 > /sys/class/gpio/export # CAN0_TERM
sudo echo out > /sys/class/gpio/gpio264/direction
sudo echo 0 > /sys/class/gpio/gpio264/value

Basic CAN Bus Test Method

# Send random data from can0
cangen can0 -v

# Send a piece of information from can0 with id: 123 and data: ABCDEF00
cansend can0 123#ABCDEF00

# Dump data receiving from can0
candump can0 -L