At 03:39 PM 4/29/00 +0200, you wrote:
>I am using 2 PICs (16f874) on 2 boards to control a system. The board
>communicate via SPI with  Fosc/4. The one board switches relays to power

) Should I use a protocol for the SPI and if so, where can I find one that
>is reliable and simple?
>
Hi!, I had the same problem about 2 months ago, An master interfase, that
read 10 slave devices using SPI , the master read the devices and transmit
data over X25 radio network, (protocol generation, and all that stuff included
on the device), but when I switched from analog loopback to a radio, the
RF generated by the radio makes all kind of weird thinks on the SPI bus,
I tested many ways to eliminate it, shielding included, but, from time to
time some error ocurr, so, what I did was write my own version of SPI bus,
but with more current un wires and 50 times slower protocol, NO MORE
PROBLEM, that was the solution!, because I only need 128 bytes x minute,
It's not necessary the high speed SPI bus, I don't know if it is your case,
but if you
don't need high speed, a software version will be better, I used RA4 for Tx
so when all Tx are 1 (no activity) there are no current because the open
collector.

if you want I can send you my code but it's a bit rude and messy (I was
runing out of time when I wrote it :-).

hope it helps.
see you.
   Leandro J. Laporta (LU2AOQ)     mail: lu2aoq@yahoo.com
 wrk: Arg. Assoc. for Space Tech.   ham: TCP/IP high speed group HSG


__________________________________________________
Do You Yahoo!?
Talk to your friends online with Yahoo! Messenger.
http://im.yahoo.com