kumquat-readthedocs/docs/interfaces/can.md
2024-05-15 10:16:30 +02:00

3.1 KiB

CAN Bus

The Kumquat offers two terminal blocks to access the isolated CAN-FD interface onboard. The following document describes how you can use SocketCAN to evaluate this bus.

SocketCAN provides a set of utilities for working with Controller Area Network (CAN) interfaces on Linux systems.

Connector Pinout Description

Location Description
X2.1 CAN High
X2.2 CAN Low
X2.3 Shield
Location Description
X3.1 CAN High
X3.2 CAN Low
X3.3 Shield

CAN Bus Connector Locations

Prerequisites

Before you begin, ensure you have the following:

  • 120R Termination Resistor
  • Secondary CAN Interface on another Computer using SocketCAN

Hardware Setup

Connect the Termination Resistor to CAN-H and CAN-L onto on of the two CAN-Connectors on the Kumquat.

Connect your Computer's CAN-Interface to the other CAN-Connector on the Kumquat.

Configuring and Setting Up SocketCAN Interface

Configuring Bitrate

To configure the bitrate of the CAN interface, use the ip command with the link option:

ip link set can0 type can bitrate 500000

This command sets the bitrate of the can0 interface to 500 kbit/s. Adjust the bitrate value as per your requirements.

Setting Interface Up

To bring the CAN interface up, use the ip command:

ip link set can0 up

This command activates the can0 interface and makes it operational for communication.

Checking SocketCAN Interface

Checking Interface Status

To check the status of your SocketCAN interface, use the ip command:

ip -details link show can0

This command displays detailed information about the can0 interface, including its status and configuration.

Checking CAN Interface Statistics

To view statistics for the CAN interface, use the ip command with the stat option:

ip -details link show can0 stat

This command provides statistics such as the number of transmitted and received frames, error counts, and interface state.

Sending and Receiving CAN Frames

Sending CAN Frames

To send CAN frames using SocketCAN, you can use the cansend command:

cansend can0 123#1122334455667788

This command sends a CAN frame with ID 123 and data 1122334455667788 on the can0 interface.

Receiving CAN Frames

To receive CAN frames, you can use the candump command:

candump can0

This command continuously monitors the can0 interface and prints received CAN frames to the console.

Analyzing CAN Traffic

Filtering CAN Frames

You can filter CAN frames based on their ID using the candump command with filters:

candump can0,123:7FF

This command only displays CAN frames with ID 123 on the can0 interface.

Analyzing CAN Traffic with Wireshark

To analyze CAN traffic using Wireshark, first, capture CAN frames using candump and save them to a file:

candump can0 > can_traffic.log

Then, transfer the log file to a system with Wireshark installed and open it for analysis.