PIC Tutorial - Wireless Boards
This time we actually need two boards, one transmitter board, and a receiver board as well. The licence free radio modules I'm using are from RFSolutions, the RTFQ1 (transmitter) and RRFQ1 (receiver), they are FM modules, with a range of up to 250m, mine work on a frequency of 433.9MHz, and they are available at low cost from a number of sources. I've provided a copy of the datasheet if you want to have a read of it.
The transmitter works off a lower voltage, so we've got a small 3.3V zener diode (D1) and a 68 ohm resistor as a regulator to provide it with 3.3V, a 10K resistor to interface the 5V logic to the 3.3V logic, and there's a couple of decoupling capacitors.
The receiver board is very straight forward, it's simply the module and a few decoupling capacitors, there is an extra output available, which is an analogue voltage related to the signal strength, but I've not connected that.
I used these modules because they are low cost, and easily available, but there's no urgent need to use these particular modules, any similar devices should be fine, but the layouts will obviously be somewhat different.
For anyone who's interested, I'm now using Abacom products for my diagrams, 'sPlan 5.0' for the circuits, and 'LochMaster 3.0' for the layouts.