Computing stuff tied to the physical world

RF12 status lights

In Hardware, Software on Dec 24, 2009 at 00:01

Here is a little setup to see what’s going on in the ether, wirelessly speaking, that is:

FlySketchExport.png

Four LEDs, blinking according to the following status signals:

  • RECV – blinks briefly for each received packet
  • RSSI – shows the value of the RSSI bit in the RF12 status
  • DQD – shows the value of the DQD bit in the RF12 status
  • ALIVE – blinks at 1 Hz, just to show that this node is alive

I changed some thresholds to get better results: RSSI threshold -91 dBm and DQD set to 7 (normally -103 and 4, in the current RF12 driver).

Here is the sketch which drives the LEDs accordingly:

Screen shot 2009-12-20 at 16.05.18.png

In this example, I’ve set up the RF12 parameters to receive group 5 in the 868 MHz band.

The result is quite interesting: DQD is flashing constantly, in an irregular pattern. RSSI blinks only once in a while, and some of these cause RECV to light up – as expected: only packets with the proper FSK format are filtered out, and only some of those are for this specific net group.

The reason for doing this will become clear tomorrow…