Can7

This repo contains a handful of terminal-based utilities for viewing real-time diagnostics using the CAN interface of MBE engine control units, as found in modern Caterham 7 sports cars.

I built these to enable me to reset the throttle position sensor on my own car, as the manufacturer reset process requires access to proprietary hardware and a companion free-to-download proprietary Windows application (Easimap).

I use a Raspberry Pi with a Waveshare 2-channel CAN HAT. You may have success with similar hardware.

Credit must be given to John Martin of the Purplemeanie blog for his series of articles on ECU diagnostics. If you're interested in learning more about the MBE ECU in Caterhams, this is a great resource.

Usage

First you must configure your CAN interface to work with the MBE ECU. On Raspbian, you can do this by adding the following to /etc/network/interfaces.d/can:

auto can0
iface can0 inet manual
    pre-up /sbin/ip link set can0 type can bitrate 500000 triple-sampling on restart-ms 100
    up /sbin/ifconfig can0 up
    down /sbin/ifconfig can0 down

All commands are exepected to be executed with the ignition on, and, if querying live engine metrics, with the engine running.

Identifying your ECU

The mbe-ver utility will extract the serial number from your ECU.

To install:

$ go install github.com/oesmith/can7/cmd/mbe-ver@latest

Usage:

$ mbe-ver --device can0
ECU version #959bd804

Running diagnostics

The caterscan utility displays live realtime diagnostics by reading. The diagnostic parameters to fetch and display are configured in a YAML file containing the ECU page and offset for each parameter, and the scaling parameters to translate the ECU values to human-readable metrics.

I've provided an example file that works with my own car. However, the locations of diagnostic parameters will change in other ECU models. If you need to develop a custom config for your own car, then you can find a full catalog in the config files shipped with the proprietary Easimap software.

To install:

$ go install github.com/oesmith/can7/cmd/caterscan@latest

Usage:

$ caterscan --device can0 --config params.yaml

Development

As well as the diagnostics utilities mentioned above, this repository also contains a small handful of other utilities that I used when in development.

• bcast - Dumps diagnostic parameters from the more primitive broadcast protocol used by the MBE ECU.
• replay - Replays a wireshark / tshark session dump on the CAN bus.
• mbe-fake - A fake implementation of the ECU-end of the CAN protocol.

These tools are typically used with a virtual CAN interface, which can be setup using the following commands:

sudo modprobe vcan
sudo ip link add dev vcan0 type vcan
sudo ip link set up vcan0