Hey,
is it possible, that a ATMegacontroller is communicating with another? Or an arduino and another arduino? If yes, how? 
regards!
Yes it is. There are many ways but using the UARTs and asynch-serial comms is probably the easiest and most common.
Also you have the consider the distance between them and required speed of the data transfer. If they are close and only need slow speed just run a couple of wires, far apart and/or high speed you will need buffer chips of some kind.
Graynomad:
Yes it is. There are many ways but using the UARTs and asynch-serial comms is probably the easiest and most common.Also you have the consider the distance between them and required speed of the data transfer. If they are close and only need slow speed just run a couple of wires, far apart and/or high speed you will need buffer chips of some kind.
Hey, frist of all thank you for your answer. I think there could be distances under 100m. I dont need much speed or bandwidth, there only a few boolean values. Could i get problems by far distances? Things like wrong values or whatever?
regards
Yes at 100M there is a good chance of problems. Look into RS-485 drivers, you can get shields with them on.
OK. I've googled a bit around but i can't find wich pin's i have to use for UART. Do i use the RX and TX Pins?