Computing stuff tied to the physical world

Trying to receive OOK data

In AVR, Software on May 18, 2009 at 00:01

Here is an experiment to try and (ab)use the RFM12B module for OOK reception, such as sent out by a FS20 remote control. First the complete sketch:

Picture 2.png

The interesting bit is that thisĀ appears to work – the LED flashes when I press a button on the FS20 remote:

OOK receive trial

Since the signal is made to come out on the AIO port 1 pin (A0), this whole unit can be plugged into a second JeeNode running the OOK decoding code from an earlier post. Like this:

OOK receive trial

The reason for using two JeeNodes is that the one receiving the OOK signal is 100% tied up in a loop polling the status register. No problem – we simply upgrade to a dual-core setup :)

Unfortunately, the combination isn’t working yet. I’ll need to use the scope or logic analyzer to figure out what’s going on. Perhaps the RFM12B’s RSSI circuit is not fast enough to faithfully reproduce OOK transitions.

Oh, well.

  1. If the RSSI status bit is too slow, or polling it has too much jitter, you could try monitoring the ARSSI signal with an analog comparator or two.

    See http://www.mikrocontroller.net/topic/65984#541030 for the location of the ARSSI signal on the RFM12(B).

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