PIC Tutorial - Wireless Boards


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.

This is a top view of the Wireless TX Board, it consists of one RTFQ1, two resistors, two capacitors, one zener diode and five wire links.
A bottom view of the Wireless TX Board, there are twenty seven track cuts, although some of them are the complete removal of track sections - this was done because the manufacturers of the modules advise you NOT to use Veroboard to mount the modules.
This is a top view of the Wireless RX Board, it consists of one RRFQ1, one electrolytic capacitor, two capacitors and five wire links.
A bottom view of the Wireless RX Board, there are fifty track cuts, although some of them are the complete removal of track sections - this was done because the manufacturers of the modules advise you NOT to use Veroboard to mount the modules.

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.

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