Computing stuff tied to the physical world

OOK unit

In AVR, Hardware, Software on Nov 21, 2009 at 00:01

Here’s an ELV 868 MHz OOK receiver, connected to the new JeeNode USB:


Note that this plug can be used for any of the four ports, simply by plugging this thing in one of the four possible orientations. In this case, it’s hooked up to port 1.

The receiver is mounted on a JeePlug for stability:


There really are only three wires: GND, +3V, and the received bit stream, which is tied to the AIO pin:


You can clearly see the built-in pcb antenna on these last two pictures.

The code for this is similar to the one used in an earlier post and basically runs a couple of bit decoders in parallel to recognize FS20, (K)S300, and EM10 commands. It’s available here. Sample output:

Screen shot 2009-11-19 at 15.02.31.png

Or have a look at the OOK relay, with which this plug will also work.

I really need to clean up and merge the different OOK decoding sketches – they all have slightly different capabilities…

One thing which would be very nice to do with this unit, is a general sketch which reports incoming OOK packets but which also uses the OOK sending capabilities of the RF12 driver to send out such packets, to control FS20 devices for example. That mould make this a general-purpose bi-directional 868 MHz OOK unit, connected via USB and controllable via simple serial-port commands.

I’ll punt for now. Don’ have time to go into this. Or perhaps I should say… exercise left for the reader :)

And maybe one day we’ll get OOK input going without extra hardware ?

PS. Good news: everything is now in for the JeeNode USB, so I’ve started shipping them.