I want to develope and interface for a cars computer along with understanding how to write a program to communicate with the cars computer. Any information how to find reference information on this subject and language used?

Thanks
Louis Drotos

 

Are you referring to getting data from the OBD (On Board Diagnositcs) port?

There isn't much of a standard, and what standard there is isn't published in detail.

This link has a bit of info for data rates: http://www.thinkythings.org/obdii/

 

The most important thing to obtain is the processor and its inputs. There may be no standard for the processor in the Engine Control Unit (ECU). The processor (really a microcontroller) may be different in each make of car, and may also change every year. That is problematic, as the instruction set will be different with each processor.

The ECU is controlled by ROM, so there is no OS. Neither is there a communication I/F. The accepted means of dealing with the ECU is to change the ROM to improve performance.

Of course, that means that somebody has a way to understand the ECU processor and so is able to change the control program to modify the engine performance. That would indicate that companies that sell ROM's for changing performance might be a source of information on the ECU processor.