http://rgwni.blogspot.co.uk/2013/05/veh ... rking.html
(and lots of previous posts going back at least 3 years!)
This is a weird-and-wonderful project to get a dashboard display giving real-time engine parameters into a 1988 Supercharged MR2 (well, if you're going to do it, do it with some style). The late 80s Toyotas had pretty sophistocated engine manangement for the time with 16-bit microcontrollers for a start, but they did not support OBD standards as that didn't come in until a few years later.
I have a surplus Android 2.2 tablet with a resistive touch screen that I want to use, but as the only communications with it are via wi-fi I need a way to send data wirelessly from a local access point actually inside the car. That's where the RPi comes in.
The project will put a PIC microcontroller in a case beside the ECU (engine computer) with buffered (high-impedance) taps into the lines from the various engine sensors (temp, O2, etc.). The PIC circuit converts the values to a simple serial data stream which is output over USB. This is read by the RPi which is running as a local access point with a server and so on and the data is then available to be read by suitable Android apps or a JavaScript web page.
In the first instance I am adding my own boost gauge based on a surplus Saab 2 bar MAP (manifold air pressure) sensor that I got hold of. This will allow testing before tapping into the car's own electronics.
Glenn