A simple Arduino project to show how to communicate with your car's OBD2 port using an ESP32-C3 and SN65HVD230 CAN bus transceiver, using ESP32 TWAI (Two-Wire Automotive Interface)
NOTE: It's fun to tinker with your car, but there is always a chance to mess things up. I won't be liable if for some reason you damage your car.
NOTE: The CAN IDs and PIDs used in this app specifically works with a 2019 Alfa Romeo Giulia 2.0L (Petrol). It's highly unlikely that the same PIDs will work with another car, you'll have to research what PIDs work with your own car.
A big thank you to the Alfisti community for reverse enginering some of these PIDs!
Some tips:
- Consider connecting your car to a battery charger while experimenting. It's highly likely that you'll spend several hours in your car while the battery is being drained.
- Diagrams of OBD2 pins are normally shown for the female connector in your car. Don't forget that those pins are in swapped/mirrored positions on the male connector.
- The OBD2 connector has an "always on" 12V pin. Make sure the wire connecting to that pin on your male connector isn't exposed so that it cannot touch other wires!
- I tried multiple pins on the ESP32-C3 to connect to the SN65HVD230, but only D4/D5 worked for me. Coincidentally these are also the SDA/SCL pins.
- Check if your car has an OBD2 Security Gateway (SGW). If so, you need to install a SGW Bypass module before you to send/receive OBD2 frames to your car.
Hardware:
- XIAO ESP32-C3
- SN65HVD230 CAN bus tranceiver
Arduino library used:
- ESP32-TWAI-CAN found here: https://github.com/handmade0octopus/ESP32-TWAI-CAN
The following information is very helpful to understand how OBD2 uses the CAN bus for communication: https://www.csselectronics.com/pages/obd2-explained-simple-intro
