How to physically connect Arduino to ELM327 and extract messages from OBD2

Hi there,

I'm quite new to hardware hacking and am trying to connect my Arduino Uno R3 to my car's OBD port.

I am told the best way to do this is using an ELM327 chip to do the decoding and tap into it.

I have bought a bbfly OBD adapter (importantly I have chosen a non Bluetooth adapter as I want to minimise lag/latency getting data from the car) and gotten it to show live data from my car using ForScan on my laptop.

Now that I have checked everything "outside the hood" is working I want to connect "under the hood" and get data into my Arduino.

The only pin out of the ELM327 I have is attached but I don't know which (if any legs) I should attach to my Arduino. I don't want to damage either component e.g. I am told that the standard RS232 connector is 12V and will damage the Arduino if it's connected to it's series input?

After physically connecting it I assume I need to use a library such as ELMduino?

Has anyone had any success with the route described above?

According to the info on Wikipedia here the ELM327 is probably a PIC microcontroller and the datasheet here says the RS232 Rx/Tx pins are compatible with interface chips so are probably 5V or 3.3V but will not be 12V. Maybe is you power the ELM327 chip and measure voltage level on Rx/Tx pins will tell you the voltage levels used.

Iā€™m really interested to know how to do this as well. Hope someone can help. Best of luck.

CAN-BUS Shield Hookup Guide - SparkFun Learn

SparkFun OBD-II UART - WIG-09555 - SparkFun Electronics

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