CAN Bus Troubleshoot on Linux

If the CAN bus interface is not showing up in Linux, here are several troubleshooting steps to help identify and resolve the issue:

Verify Hardware Setup

Ensure that your CAN hardware is properly connected (CAN interface, transceiver, etc.).
Check if the device is powered on and working. For USB-to-CAN adapters, confirm that the USB connection is secure.
Confirm that the CAN device supports Linux.

Check Kernel Configuration

Ensure the kernel is configured with CAN support. The following modules should be present:

CAN core: CONFIG_CAN
CAN RAW protocol: CONFIG_CAN_RAW
CAN Bit-Timing calculation: CONFIG_CAN_BCM
CAN SocketCAN drivers: Drivers for your specific CAN interface (e.g., for USB CAN adapters, the appropriate driver should be loaded).

Run the following command to check if these modules are loaded:

lsmod | grep can

If the necessary modules are not loaded, you may need to compile the kernel with CAN support or install the correct kernel modules.

Identify CAN Device

Check if your system recognizes the CAN device by running:

dmesg | grep -i can

This will display any relevant kernel messages about the CAN device. Look for errors or any mention of the device being connected or detected.

Check Available Network Interfaces

Check the list of network interfaces with:

ip link show

Your CAN interface should show up as something like can0. If it doesn’t appear, your device may not be recognized or the driver may not be loaded.

Check for USB CAN Interface

If you’re using a USB-to-CAN adapter, verify the USB device is recognized:

lsusb

This command will list all connected USB devices. Ensure your USB-CAN adapter appears in the list.

Manually Bring Up the CAN Interface

Sometimes the CAN interface may exist but is down. You can manually bring it up using ip or ifconfig:

sudo ip link set can0 up type can bitrate 1000000

Replace can0 with the appropriate interface name, and set the correct bitrate for your CAN bus (e.g., 1000000 bps).

After bringing up the interface, check its status with:

ip -details link show can0

Install CAN Utilities

Ensure that you have the can-utils package installed, which includes tools for interacting with the CAN bus:

sudo apt-get install can-utils

You can then use candump to verify if messages are being received on the CAN bus:

candump can0

Check Drivers

If you’re using a specific CAN interface (e.g., USB-to-CAN), ensure the correct driver is installed.

For common USB-to-CAN interfaces like the PEAK CAN interface, the kernel module is typically peak_usb. Check if it’s loaded:

lsmod | grep peak

If the correct driver isn’t loaded, you can load it manually:

sudo modprobe peak_usb

Check for Conflicting Drivers

Ensure that there are no conflicting drivers or network settings that could prevent the CAN bus from functioning properly.

For example, if you see a virtual interface for CAN but the real device isn’t listed, that could be a sign of a configuration issue.

Check for Errors

You can check for errors in the CAN bus by looking at the dmesg output, or by checking the error counters:

ip -s -d link show can0

Look for any error messages or dropped frames.

Firmware and Software Updates

Ensure your firmware and drivers are up-to-date, especially for USB-to-CAN adapters.
Check the manufacturer’s website for updated firmware or Linux drivers.