While working on my projects, I did several attempts to depict Mazda CAN protocol, to find useful information. For example, getting the shift position for the “smart “mirror project and the fuel level for the fuel reminder. There are many products available for the OBD2 protocol. One good product is TouchScan with Mazda extension, which allows you to access every module in the car for diagnostic purposes. Using this tool, I figured out how to get access to the fuel gauge on the console, instead of using the sensor in the tank. However, while it is a very useful tool, it does not provide access to real-time information available on CAN bus as broadcasted messages.
OBD2 protocol is query-respond based. You can get information by sending a request to the addressed module, but this is not the same as getting information from live broadcasted messages, without any delays.
Mazda uses two separate buses, HS-CAN or High-Speed 500khz and MS-CAN Medium Speed 125 kHz. It is well documented in the Mazda Work Shop manual, but without actual IDs for each module, which is proprietary Mazda’s information, not available for public.
I decided to make a dual-channel CAN logger/bridge, which will allow me to record messages from individual modules as well as logging from two buses. I found an old Raspberry Pi board, which will be perfect for this project. Two SPI CAN modules on top of it will do the job.
Using Python programming language it will be easy to do filtering and bridging between CAN segments for separate logging on a common bus and individual modules.
My goal is to figure out how to control warning sounds, get access to the switches on the steering wheel and central console as well as some basic information, like speed, steering position, etc., in real-time.
First, I logged 10 minutes drive and converted it into an Excel spreadsheet. The next step will be logging from individual modules, using bridge option in my sniffer.
Started my list MX-5_CAN (updated on 3/14/17), shift position, wheels speed, steering column angle decoded, work in progress…
Some useful links: