Thread: Open-source OBD-II data logger (based on Arduino)

I have developed an open-source OBD-II data logger, which displays (on a 128×64 OLED display module) and records (to a SD card) the OBD-II data (engine RPM, speed etc.). The device is based on Arduino, a SD reader breakout board, and a monochrome OLED display module.





By pulling out the SD and inserting it into computer's SD card reader, the data can be illustrated into a chart like this:



Objectives:

• Displaying realtime engine RPM and vehicle speed on OLED screen
• Recording realtime OBD-II data to SD card in text-based CSV file format
• Illustrating the recorded data in as chart with two data lines

Recorded data includes:

• Engine RPM
• Speed
• Throttle position
• Engine load
• Engine coolant temperature
• Intake pressure
• Intake temperature

The recorded data is stored in a SD card in the format of CSV. Each line represents a record with time, data type and data value like this:

[Time Elapsed],[Data Type],[Data Value]

Time Elapsed is the time elapsed in milliseconds since previous data record. Data type is the OBD-II pid number which is defined in the OBD-II library (e.g. 0xC is engine RPM). Here is an example data clip:

169,D,0
171,11,12
170,43,21
165,B,30
175,C,705
169,D,0
170,11,12
171,43,21
170,C,702
169,D,0

For more details and source code, please visit my website.