Wireless Link using Hope RF modules


Senior Member
Well I finally beat the RFM42 transmitter and RFM31 receiver into submission and came up with a configuration that actually works.

The transmiiter is merrily sending a 'Hello World' message from one side of the workshop to a receiver on the other, the received message displayed on a AXE133Y OLED.

A document with an explanation of how it all works with pretty pictures and circuit diagrams is enclosed. Its a working setup, I am waiting for the PCB for the receiver to arrive so I can build it into a box.

The only range testing I have done so far is out in the street, with the transmitter on 434Mhz at 1mW the reception range is about 60M, thats just using loose bits of wire for antennas.

How fast the things will work I dont know yet, but 10kbps is fast enough for simple messages.

What interests me now is the RFM22 tranceiver, the code should be substantially the same, but the option of being able to send commands and receive replies all from a very compact device is interesting.


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New Member
Great stuff. I've been nosing around the RFM12b but having never used a RF modules before I'm beginning to think the RFM22 or RFM42/RFM31 might be a better idea to start with. The extra intelligence seems to make life a little bit easier. It'll be useful to see how you've done things.


Senior Member
Getting these modules working, for data telemetry, was a major struggle, at least for me. There are some results of propagation tests here;


And I have some improved code for the 20X2 transmitter and 28X2 receiver that allows some structure to the packests being sent such that a packet of;

'T2Hello World' is a text packet that displays 'Hello World' on line 2 of the OLED display.

'G1xxyyzz' is a GPS data packet that sends 3 words of data, altitude, distance and direction.

Have not yet got around to using the RFM22 yet, but that would be the module of choice I think, given that it has TX and RX capability. Be careful with the higher power units, the legal limit for such devices tends to be 10mW, the RFM22 and RFM42 are capable of 100mW.

Good luck.