After yesterday’s post about modding the RFM12B to receive OOK RF data, here’s a new option which goes the other way: add-on hardware for 433 MHz.

Meet the OOK 433 Plug:

This plug can probably be used without antenna, but adding one is bound to increase the maximum reception range (I haven’t done any range tests yet).

The receiver output is tied to the AIO pin, which must be configured as input on the JeeNode. The transmitter is tied to the DIO pin, to be used as output pin.

Both receiver and transmitter can be operated from 3..12V (I’ve only tested with 3.3V and 5V, so far). For the transmitter, I would expect the power output and range to increase with voltage, but even at 3.3V things seem to work quite well in both directions. There is a jumper to select between PWR and +3V as power supply, and there is an optional series resistor for the receiver output, which may be needed at higher voltages (normally, it can be omitted by closing that second jumper).

The reason for creating a separate plug is that it allows a single JeeNode to operate simultaneously on the 433 MHz and 868 MHz frequency bands. As suggested in the comments on yesterday’s post, a modded 868 MHz RFM12B can probably be made to receive 433 MHz OOK signals, but the receiver sensitivity is bound to be fairly low since the RF circuitry is really dimensioned for 868 MHz. Haven’t tried this, though.

There are several sketches which can be used with the OOK 433 Plug. To use the receiver on this board with little or no adjustment, try recv433_test.pde or ookRelay.pde. For tranmission, there is the send433_test.pde sketch.

I expect to combine and integrate code from the different OOK and relaying sketches in the near future, now that this plug has been created, but for now you’ll have to tinker with what’s available.

If you have suggestions (of better still: code or docs) for new protocol handlers to add and implement on a JeeNode, please let me know or share it on the discussion forum. It will interesting to see how many OOK protocols on 433 and 868 MHz we can figure out and implement, to make this all truly versatile for lots of different RF devices out there.

All code and docs are in the Café, with the OOK 433 Plug available from the shop, as usual.

Enjoy!

Note – This server was down on Jan 28, from about 1:00 to 10:00 (CET). I’m investigating what happened.