RejsaCAN = ESP32 + CAN

edited June 2022 in DIY builds
I got tired of my stacked multiple boards and extra components so I made a small board that has exactly what I wanted:

- ESP32

- CAN bus port that can be plugged in directly to the OBD2 port or be connected directly to any of the cars CAN buses.

- Powered by the car's 12V with automatic shutdown (so it can stay plugged into the OBD2 port or example)

So with this small board I not only have CAN but Wifi with all networking you can think of, Bluetooth/BLE, USB... plus both SPI and 12C buses to connect to just about any sensor, display or other peripherals to drive, sense or measure. And some extra pins for ADC, DAC, PWM...

Small. I like small :blush:

I had JLCPCB make ten boards but gave away some of them to friends so I made another batch :smiley: If anyone is interested in a board, first read through the different pages on github (link below) and then email me.


I also made an even smaller housing:



  • edited November 2021
    This is wonderful! Haven't had the time to tinker with it yet, but it seems perfect. You need to send me the connector and the box at some point :smile:

  • Very cool! Another open source project that I'm helping out with, we use the Macchina A0. Same idea, esp32 in a small package. Of course it's a little overpriced for what it is, but I was fine with $70 USD delivered for such an easy solution.

    A guy wrote BLE to ISOTP20 firmware and phone app, we are doing high speed ram logging and ecu flashing over ble.
  • Sweet! I was thinking about doing something very similar, and even started designing a custom board on JLCPCB, but one of the chips I used is permanently out of stock. Glad you were able to find better alternatives!
  • Machina A0 is very similar hardware, it's a very nice piece of kit too

  • Very nice solution!
    I more or less just start with reverse engineering CAN-Bus, and used to work with K-Line in the past.
    This seems to be a very good startingpoint!
    I´ll follow the project :)
  • Neat solution. I really like small footprint and obviously the open source sw and esp world behind it. Do you still have one of the boards available for shipping? I’d really appreciate one of these. Living in Europe as well.
  • edited January 2022

    Currently all out. I've ordered a few more boards but they've ended up a bit more expensive. Email me at if you're still interested. I actually also made a few using engineering samples of the brand new ESP32-S3 and an SD card slot and a switchable 3,3V 400mA output.

  • @aol Did I send you a housing and OBD2 plug?

  • @MagnusThome nope, if you have them please send :smile:
  • Hi @timurrrr @MagnusThome

    I am struggling to get the rejsaCAN v3.x running with Racechrono to log CAN-data (Powertrain CAN). Since I am not that deep in programming /protocols and my time is limited to dive in this stuff I would like to ask for an code which is already adapted to this board. If there aren't any ready solutions available I would pay for the service.

Sign In or Register to comment.