Obd2 protocol

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#1
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Hello
I would like to ask if it is possible to convert a non obd2 car to obd2 protocol with some external unit.
I have Rx7 fd3s and also I have the complete ecu pinout from all sensors.
My goal is to convert all this signals to obd2 protocol and after that to install a nice obd2 analyze module like hks have with instruments logs peak hold etc.
Any idea?

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Seems like if you read the sensors direct (and you are an ok windows graphics programmer...) you could update faster than obd. Used to be every 250ms using ISO9141. Probably a lot faster now using CAN.

Imagecraft compiler user

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I'd second Bob. It might just be cheaper and easier to use an aftermarket ECU. If you are worried about EPA laws etc, just have the aftermarket ECU read the sensors and not control the engine.

To do this yourself, from scratch, you're facing a large learning curve so expect to spend a very large amount of time. You can look at megasquirt to get a headstart.

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You'll probably find that the ECU can supply most of the information to you already, even if it's not in OBD format. OBD is there mostly to provide error messages, not running data.

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The "trick" here is to understand the basics of OBD2 and be aware that it is quite probable that Mazda are using using manufacturer specific codes to comply with OBD2 (which is really a US California statute that they just use everywhere because it is easier), which are allowable with OBD2 and a nightmare to decode.

For this reason alone, I would suggest an after-market ECU like the Apexi Power-FC.

FWIW and FYI - I have a Nissan S15 (SR20-DET - which was surely conceived, invented and designed by GOD as the omnipotent 2.0L power-plant) and have decoded the entire command set for it (Power-FC) and also built my own AVR based controller which can display and decode and even re-program the Power-FC (on the fly ... if required)with an Atmel AVR. Since doing this, I have discovered that the command set or protocol sent over the wire is pretty much the same with all Apexi ECU's, except for a few unique capabilities that individual cars/engines have. Here Apexi just use extensions to their command/protocol which make sense once you have "cracked" their protocol.

FWIW, my car has been "custom tuned" with an after-market turbo and a few other add-ons to help it produce > 240kw atw (double that as shipped by Nissan), in addition to being inspected by the local statutory authorities to prove it meets "emission compliance" regulations and is fully "engineer certified" and registered with the State Statutory Authority" as being "legal".

If you don't want to go down this path, an alternative might be to look at just reading the sensors as other have suggested and doing it all yourself, but you won't make an ECU (or hack into an OBD ECU) for what a Power-FC or commercial equivalent and a little time will cost you.

Cheers, Brenton

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I have power fc with commander and works great and i can monitor all the sensors. But i love the gtr instrument panel thats why i am searching to build something like that.
Ofcourse as you said is better to build a project with atmel log data and measurment. But it is impossible with my knowledge on avr to drive a color tft monitor and also draw the beautiful instruments.
Maybe the best way is to use pc and atmel with usb interface but also in pc i can not build a project with instrument just know little about visual basic.

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Maybe that would be a good project for several avrfreaks to collaborate on... draw gauges with rotating needles in c#, VB, java with inputs on rs232?

Imagecraft compiler user

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This will be a great project not only for cars but for many applications .
Today you can find a very small mini atx motherboard with cpu,vga on board so you need only usb stick to boot the system and run your application.
Much better if it is in java lang you can run linux complete free of charge.

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Nothing is better in Java. Write once, crash anywhere.

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petros047 wrote:
I have power fc with commander and works great and i can monitor all the sensors. But i love the gtr instrument panel thats why i am searching to build something like that.

Perhaps you are just looking at it all wrong. Many of the current crop of car audio systems now have TFT displays which can accept a composite video signal to display DVD's etc. My thought in this regard would be to get an existing video-generator device (there are a few simply kits that are cheap) and pump data to that which would in-turn draw your gauges etc. You could also do the video generation in a second AVR. There are plenty of projects here on AVRfreaks that would get you started in that area.

In short, don't try to drive the TFT directly. Generate a video signal in another AVR or $50 kit type product and use a standard video display. You can even find these pretty cheaply now as they sell them for fitting into headrests etc.

The PFC for the RX-7 is pretty neat, and you will get a lot more data out of the PFC than you will from the factory ECU.

Cheers, Brenton

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Can you suggest me a video generator who i can easy draw some instruments?
This is very good idea.
The only negative in this case is that you lost music when you turn the multimedia system to av in.

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There are a variety of options.
You will find a few projects in the Academy of this Forum and elsewhere.

Try looking for OSD or OnScreenDisplay.

In just a few minutes, I found quite a variety of options from basic silicon to complete solutions.

http://www.maxim-ic.com/datashee...
http://www.sparkfun.com/products...
http://www.decadenet.com/
http://www.blackboxcamera.com/pi...

I'm sure there are a few creative solutions to the video-switching and loss of audio, but I haven't really looked at a/v car stuff for a while now.