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I2C in an automotive environment

I'm starting a system design for my car that will need an interface between each subsystem (alarm and locks, engine control, windows and lights, stereo, displays ect...) I chose I2C over RS-485 because it is widely accepted and easy to impliment with minimal parts. Has anyone tried using it in an automotive environment? I'm concerned there might be to much interference causing data transmittion problems.

Is there maybe a better thread for this question someone knows about?

Thanks for any input

-Amos

Reply to
Amos K
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I2C is widely accepted and eeasy to implement with minimal parts. The traditional I2C is not useful outside the box for anything that needs reliabity, because it is quite sensitive to interference (unbalanced bus with open collector drivers and weak pull-up) and the communication protocol/ICs does not have any useful built-in error detection/correction.

I have heard somebody mention I2C over RS-485. I have not heard much of it or seen it used anywhere, so I doubt that it woudl be widely accepted.

I have not tried to use it in automotive enviroment. I have used I2C on some other things...

--
Tomi Engdahl (http://www.iki.fi/then/)
Take a look at my electronics web links and documents at 
http://www.epanorama.net/
Reply to
Tomi Holger Engdahl

I was worried someone would say that. I've thought about using shielded cable. Triax most likely, if I can find some. Think that would help enough?

I've not heard of I2C over RS-485. I'll do some research but it seems to me that it makes more sence to do straight 485. If I had a I2C sensor I wanted to hook up it might be worth looking into. Then again it would probably be easier and cheaper just to hook the sensor to a micro and put that on the 485 drop.

Thanks for your input.

Reply to
Amos K

Can't sya for sure if triax would be gopod enough. I2C in car environement sound very unrelible to me.

Here are some lins for I2C-RS485 adapter plans I have found:

I2C - RS-485 adapter

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I2C Serial Port Adapter & Extender

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Using I2C only on very short local communications between the sensor and microcontrolelr, then the micrcontroller communicates through RS-485 sounds the most sensible solution. It coudl be a good idea to add some checksum etc. to the communcation packets to make sure that data gets through right and errors are detected when they occur.

--
Tomi Engdahl (http://www.iki.fi/then/)
Take a look at my electronics web links and documents at 
http://www.epanorama.net/
Reply to
Tomi Holger Engdahl

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