see this link http://www.mikrocontroller.net/topic/161885 last post from ansel
Is it possible to receive OOK without extra hardware on a jee-node ?, I don't read they use any extra hardware ,or maybe I am missing something.
dem undokumentierten OOK-Modus des RFM12
(4 posts) (3 voices)-
Posted 2 months ago #
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Interesting! All I see in the code is that an extra "DATA" pin has been hooked up as digital input. I wonder which pin that is. Haven't looked closer yet - could it be that he's putting the RFM12B in a special mode and then reading out the FSK/DATA pin?
Posted 2 months ago # -
Yes that could be the trick,I 'll try to find more info .(FSK/DATA)
Posted 2 months ago # -
The RFM12B is probably has FIFO mode disabled in the configuration setting register. When receiving, the raw data is then available on the DATA/FSK/FSS pin (not connected on the Jeenode).
When an OOK tranmitter is sending and the send frequency corresponds to the RF12 center+deviation frequency, the DATA pin is set high. However, this doesn't mean that it returns nicely to zero when the OOK transmitter stops sending; that would only happen if there were a signal on the center-deviation frequency.
In the absence of a signal, the RF12 will try to get a signal out of the noise and the DATA pin will randomly flipper between 1 and 0. I suppose you could extract an OOK signal from this behaviour if the flippering happens relatively frequently.
BTW: I didn't come up with this myself. On the Silabs site there is a document called "RF Wireless foundation course book one" where this trick is described: http://www.silabs.com/products/wireless/EZRadio/Pages/Si442021.aspx under resources->documentation->miscelaneous
Posted 1 month ago #
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