OBD-II ECU Interfacing ?

Areal Person

Has anyone done any OBD II ECU Interfacing ?

I'm trying to figure out how I can use my Propeller
to access all of the Diag. data on my car using the
OBD II Interface port.

I want to build a Propeller Scan Tool for my car.

Thanks,
-Areal

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I have a tree growing out of my head, but

what do you expect ? I'm a programmer.

parts-man73

Well yes, I am.

I attached some pictures of my project.

There's a 6.4" LCD screen that I fit into this enclosure, along with a SpinStudio mainboard, with a AV board to drive the screen and a custom PCB I made for OBD II interfacing.

I designed this custom PCB around the ELM 327 chip. Plus alot of support components. The ELM chip does all the talking to your cars onboard computer. You simply query the ELM chip serially with the propeller to glean any information available.

I'm stuck on the software and haven't had a chance to work on it. It's simply a matter of requesting, then parsing serial data. I had it working well with my 1998 Dodge, but then I bought a newer (2003) truck and the data I'm getting back is formatted slightly different. Since I want it to simply plug into any car and work the same, I want to write some routines to parse the data correctly no matter which protocal the car speaks.

I'll be away from my computer all weekend, so don't be put off if I don't respond to any questions until monday.

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Brian

uController.com - home of SpinStudio - the modular Development system for the Propeller

PropNIC - Add ethernet ability to your Propeller! PropJoy - Plug in a joystick and play some games!

SD card Adapter - mass storage for the masses Audio/Video adapter add composite video and sound to your Proto Board

awesomeduck

parts_man: Any chance you can share the schematics? I just purchased the ELM327 and various parts but reading the data sheet is says the ELM must be connected to the same 5V power supply as the CPU. How do you interface a 5V and the 3.3V Propeller in this case?
Any chance you are selling the ELM327 interface PCB in the photos?

Post Edited (awesomeduck) : 2/7/2009 10:16:56 PM GMT

Hugh

More or less finished something similar but not as neatly as Brian, not neatly coded (at the moment).

Rather than trust myself to make a circuit for an ELM327, I bought an ELM327 to RS232 converter via eBay and connected it to a Propeller protoboard (two pins). Another pin drives the LCD display and three pins deal with switch positions. Another two pins drive the LEDs.

An SD card allows the parameter being viewed to be recorded. A VGA display was used for debugging purposes during development.

12V supply from the car drives the RS232 converter and the protoboard.

Hope this helps someone...

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Hugh - the thinking woman's Geoffrey Pyke.

Tired2

Thanks Areal...,

Any chance of posting code? (dirty or not)

I have that same converter, and I was curious how you select modes over serial and such... I have not even had time to hook it up with the factory software yet.

(for anyone wondering, these converters are $40-50 on ebay after shipping)

Hugh

Sorry for the tardy response! Been recording data to an SD card and giving it to the tuning chaps....



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Hugh - the thinking woman's Geoffrey Pyke.