Kernel hacking for the RFM12B

RFM12BI’ve been busying myself with fixing up and adapting the RFM12B Linux driver. My first thought was simply to give people support for sending and listening for OOK signals as an extension, then taking the device support in the rtl_433 decoder to extend RFM12B driver to include lots of OOK device support for things like weather stations and energy monitors.

JeeLib already does most of this work on Arduino so for the most part this is simply a matter of joining lots and lots of code together from different places and making sure it sits right. I’ve decided that in order to do this it would probably be better to re-write the driver while trying to fix some of the original driver’s TODO list along the way.

The driver will loosely allow :-

  • Compatibility with the original RFM12B driver & original JeeLib compatibility.
  • Send OOK, FSK messages to devices.
  • Listen for OOK, FSK messages from devices.
  • Set tuning to a specific frequency.

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Fitted Salus RT800RF

Fitted the Salus RT500RF today, this wasn’t such a difficult job but I did blow two fuses following bad advice. The wiring of my Vaillant Turbomax doesn’t require bridging the COM and Live as suggested in many online videos, nor do I need to add a LOAD resistor between pins 4 and 5 on the boiler.

RT500RF to VaillantHere’s a simple diagram to demonstrate how to connect the Salus RT500RF to a Vaillant. Now simply when pins 3 & 4 of the Vaillant are bridged they will start the boiler up. An optional pipe thermostat to switch the boiler off if the pipe overheats can be inserted in between pins 3 on the Vaillant and N/O on the Salus RT500RF.

Now I’m getting ready to start sniffing the airwaves with my SDR and my RFM12B to see what I can do. All I really want is to set/get the current state of the boiler.

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Upgrades… Salus RT500RF 868MHz wireless boiler control

RT500RFI’ve just received a Salus RT500RF in the post. I’m pretty much all prepared to hack this thing, at first I’ll sniff the airwaves with the RTL-SDR and try and get a handle on how it works. There’s been at least one blog article regarding this unit so I’ll also have a dig around them and see what they can tell me too. The idea is to get the Raspberry Pi with the 868MHz RFM12B to send a signal to turn the heating system on/off, and if possible, interrogate the current state of the boiler.

This will be the first stage in smartening up the house. The OWL CM160 and the Salus RT500RF are the first devices that I’m going to mess with as they’re the most useful to me right away. Next I’ll be turning my hand to Oregon Scientific weather sensors, Wireless door bells and other hardware on the 433/868 bands. These bands of course are used in Europe and some other locations, the equivalent is 315/915 for the US. So if you’re following my work then make sure you pick up the right bands for your location. It’s always best to buy radio transmitters and receivers in your own country because the likelihood of anything being on sale which isn’t allowed is reduced.

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