If you're not committed in Hardware yet, consider changing to
an 18F458. The CAN network offers lots of low level support for
error detection, bus arbitration, and neato stuff like that in hardware.
All you'll need to add is a simple 8 pin driver chip to make the interface
work. CAN is daisy chain, and you DO get longer distances for lower
data rates.

There are others on the list with far more experience with CAN than
myself, but I'm learning as fast as I CAN. 8^)

Lyle Hazelwood

----- Original Message -----
From: "Phil" <Phil@PKELLER.NET>
To: <PICLIST@MITVMA.MIT.EDU>
Sent: Monday, February 24, 2003 7:43 PM
Subject: [PIC}: Low speed/long distance communications


> What would you suggest for serial communications between PIC's
> (16F877/876's) that are located about 200 feet (60 meters) apart and on
> Cat 3 (or if I am lucky Cat 5) cable?  The data rate is slow, much less
> than 1,000 bps.  I have looked at I2C but it appears to be limited to
> only a few meters.  Did I miss something in the spec that allows it to
> operate at longer distances and reduced data rates?
>
> I would prefer a "daisy-chain" interconnect but if necessary a star
> topology could be implemented.
>
> Is it time for a roll-your-own interface?  Currently I am not I/O
> limited but that may change :~)
>
> Data, Clk and Vss would seem to be the easiest and minimum number of
> signals.
>
>   Your thoughts and suggestions are appreciated.
>
> Phil
>
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