Getting two PICs to talk to each other in it's simplest form is ONE WIRE (plus Vss/Ground) connected from one PIC to the other. No other Hardware.


However, this is a HUGE topic. You can do a posting every day for a year and still not cover everything.

There are so many variables. A solution encompassing one set of variables, would be totally inappropriate for another.

Before making any kind of move in any direction you need to be armed with your design criteria...

1. How far apart are the PICs?
2. Are they both on the same PCB?
3. How many wires can you connect between the two PICs?
4. If not on the same board, are they connected by Cable?
5. If so, how many wires have you got to play with?
6. Is the interconnection going to be in a noisy environment?
7. Are you interconnecting by Laser, Infra-red, Wireless, Satellite or other method?
8. How FAST does the Data Transfer need to be?
9. Are you sending a BYTE, WORD or whole heap of Data?
10. Do you need verification that the Data has been Received?
11. Is the interconnection Bi-Directional?
12. If Bi-Directional, is that just for verification of reception or for actual Data flow?
13. Are the PICs xtal or resonator controlled? All of them?
14. How many of them are going to be interconnected?
15. And by what methodology (peer-to-peer, slave-master, token-passing, TCP/IP etc)?
16. Are the PICs going to be busy doing other things whilst the communication is being transmitted/received or otherwise exchanged? Or are they just sitting there waiting for things to happen?

That's just a VERY brief (and incomplete) list.

Answers to the above will probably pose more questions, and only then can you start a plan for getting these things connected and talking.