An ELM327 to serial interface for the carputer was constructed last time but it was never used. Now with the inception of a new project, it is taken back to life for a new purpose. It will be reading the car info and printing it out on a display.
the original interface
The MAX232 IC was removed and connected directly to the Teensy 2.0 board. LCD driver is taken off my old project and all serial data is printed on the screen. Before deciding what to display we need to know what data is available on the port
reference for OBDII PIDs can be found here : http://en.wikipedia.org/wiki/OBD-II_PIDs
Method is reading the PIDs that lists what are the supported PIDs, namely 00, 20, 40, 60 etc
the new hardware
Logically, the first PID (01 00) would indicate if the next set of PIDs is supported in the last bit. And once the last bit is zero, later set of PIDs would no longer be supported as shown above.
The code decyphered
This is what the final interface would look like
Before the LCD was used, the data was displayed on 7-segment but later deem to be too limited.
Here’s a video of it in action
Digital tachometer using ELM327 and Teensy 2.0