At 02:17 AM 2/28/02 +1100, you wrote:
>Hi all,
>
>I am a relative newbie, and am designing a series of products based on the
>PIC16F87X and possibly the PIC16F628 that will all need to communicate with
>each other (multi Master) over distances of up to say 50m.
>
>Is I2C a suitable choice?

No. It is intended for very short distances. You want, at a minimum, RS-485,
for which you can use the on-board UART in those chips. I prefer isolation
(optical or transformer) for noisy environments.

>Can I run the PICs as slow as 4MHz, or would I
>need to go higher than this? I plan to send simple commands and
>acknowledgements only.

4MHz should be fine as far as comms are concerned.

>Also what is a "Controller Area Network"

CAN is a relatively simple network used in automobiles and similar situations.
It's also part of the industrial standard Devicenet. Do a web search and
you can find lots of information on it.

Here's a presentation that should get you up to speed:
http://www.ece.cmu.edu/~ece540/lecture/09_can.pdf

>Sorry if these are silly questions.

The only silly question is one that should have been asked but, wasn't.

Best regards,

Spehro Pefhany --"it's the network..."            "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com
9/11 United we Stand

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