RF433 transmitter and receiver.
Above is a cheap and cheerful wireless transmitter and receiver. (Approx £ 4.50 on EBay UK).
I investigated libraries to use these, and decided on
RadioHead, which is Copyright (C) 2008 Mike McCauley
and distributed under the open source GPL - which means you can use it
as much as you like at home.
The library has several methods of working; the most basic protocol (RH_ASK) and the first example worked well for me.
However, do note that the library code can and should be read to determine it's usage .
I started using these to communicate with my remote controlled car with a joystick, so expect all code below to be
developed with that purpose in mind.
For the receiver: connect either of the DATA pins to the Arduino pin 11 - both pins output the same info.
For the transmitter: connect the DATA pin to Arduino pin 12.
The pins 11 and 12 are defaulted in the library RH_ASK.h; I had no need to investigate this further or to change them.
Always keep both pins 11 and 12 free. If you have the Tx on one arduino, and the Rx on a different arduino, you must still keep
pins 11 and 12 free on BOTH arduinos.
With a 5V power supply and no antennae, I have a range of about 1 metre. Okay for prototyping and testing.