AVR-Chat

I would like to transfer data some distance (100 feet in one case, 400 feet in
another) between AVRs and I'm looking for the least complex, least expensive way
to accomplish this.  Environment:

1) Using facilities available on AVR processors (such as UART, TWI, etc.)

2) I have cable in the ground which is Telco grade, gel filled, direct bury
cable with 6 twisted pair

3) Speed is not critical.  Of course I'd like to go as fast as possible but I'm
willing to sacrifice speed to keep complexity/cost down ... Well, I'd rather not
go back to the 110 bps days!  :-)

4) Multimaster is desirable

I'm thinking that the solution will use some king of differential driver.

I was doing some reading about TWI but it's unclear to me if this works in this
situation.  The only thing I could find about distance limits was that the bus
capacitance must be below 400pf but I don't know the capacitance of my cable ...

BTW:  I think this forum is appropriate for this, if not, please let me know.

Suggestions?

Cheers,

Chuck Hackett
"Good judgment comes from experience, experience comes from bad judgment"
7.5" gauge Union Pacific Northern (4-8-4) 844
http://www.whitetrout.net/Chuck