Computing stuff tied to the physical world

Updated RF12demo

In AVR, Software on Oct 29, 2009 at 00:01

The RF12demo software which comes pre-loaded on all JeeNodes and JeeLinks has been extended a bit:

Picture 1.png

The new commands are:

  • l – to turn the activity LED on or off, if present
  • f – send a FS20 command on the 868 MHz band
  • k – send a KAKU command on the 434 MHz band

The new FS20 and KAKU commands were added so that a JeeLink can be used out-of-the-box to control the commercially available remote switches of these types. The updated demo is included with all new JeeNodes and JeeLinks from now on.

For example, to turn on channel 1 of a FS20 unit with housecode 0x1234, you can type in “18,52,1,17f” – i.e. the house code in bytes, the channel, and 17, which is the “on” command. Likewise, to turn on channel 1 of group B on KAKU, type “2,1,1k”.

The KAKU transmission range is not very high because the RFM12B radio used is tuned for the 868 MHz band, but even more so because the attached wire antenna is completely wrong for use at 434 MHz. If you want to use this for controlling KAKU devices and don’t get enough range, try extending the antenna wire to around 17 cm, i.e. double its current length. You can just attach an extra piece of wire to the end.

Which – unfortunately – is going to substantially reduce the range at 868 Mhz… so if you really want to use both frequency bands, you’ll have to use two JeeNodes or JeeLinks, each with their own properly sized wire antennas.

For more info about FS20, see these posts on the weblog. For KAKU, see these.

  1. Cool one again Jean-Claude!

    does it “sniff” for FS20 trafic as well?

  2. i don’t no if i question this before : Is it possible to use the new rfm22 instead of the rfm12b on the jeenode ? Of course, a new jeenode v5 has to be build sometimes, because of more pins at the rfm22 module, but in the description of the rfm22, OOK sending & receiving is described as funtionality of the rfm22. may be then ” sniffing for fs20 traffic ” is possible ?

    • I have not yet looked into the RFM22 / RFM23. I was well aware of these new units when I designed the JN v4 and concluded that the RFM12B is more than good enough for a huge number of usage scenarios. So don’t hold your breath w.r.t. any JeeNode change soon – the new radios are twice as expensive, draw more power when active, do not do that much more, and the RFM12B clearly is not going away. One thing which still needs to be researched is whether these new modules could do OOK and FSK at the same time. If not, you might as well get a separate receiver for OOK, which is what I do in the relay.

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