I'd be inclined to use an 8-pin PIC as the buffer, and let it to convert to
a different protocol (async serial as in RS-232) that's better suited to the
distance.  At a modest baud rate, you can probably drive and receive the
data with bare PIC I/O's with a little R and C on the driving end to keep
the spurious emissions down.

> -----Original Message-----
> From: Jason Wolfson [mailto:jason@LIPIDEX.COM]
> Sent: Tuesday, October 03, 2000 10:52 AM
> To: PICLIST@MITVMA.MIT.EDU
> Subject: [EE][PIC] Long distance I2C
>
>
> I'm trying to run a remote I2C temp sensor over phone
> cable 50m away into a PIC. It needs to be very reliable and cheap.
>
> My first assumptions are: Run slow out of the PIC since I can
> control the bit rate and therefore reduce effect of slew due to cable
> capacitance.
>
> Second, use a driver of some sort out at the I2C sensor to isolate
> the I2C sensor chip from cable capacitance/impedance and protect from
> induced transients.
>
> Has anyone done this and know all the "gotcha's"?
> Easiest way of implementing a driver/receiver circuit?
> Transient protection? etc....
>
>
> thanks,
>
> Jason Wolfson
>
> ___________________________________________
>  Lipidex Corp
>   50 Franklin Terrace
>     Duxbury MA 02332
>           781-834-1600
>               781-834-1601 FAX
>                       jason@lipidex.com
> ____________________________________________
>
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