Hi All
I'd like to control my central heating from the Internet. The current setup is a wireless stat in the hall and a wireless receiver in the airing cupboard, next to the boiler. I did consider removing the wireless receiver, and fitting a Photon board and controlling it that way, but I don't want to mod the system such that a new occupant can't use it if we sell the house.
I did some searching and found this excellent page:
http://www.stevenhale.co.uk/main/2013/08/home-automation-reverse-engineering-a-worcester-bosch-dt10rf-wireless-thermostat/This guy didn't own a storage scope, but managed to work out the protocol using a sound card and Audacity (sound recorder) to display the waveform.
In his example, the protocol is very simple; it sends a series of 1s and 0s as a training sequence then a couple of bits at the end signify boiler on or off. His system used a 433mHZ transmitter/receiver and compatible hardware is available from eBay for less than £2.00.
Flush with the promise of a simple and cheap solution, I bought a transmitter and receiver. Then I checked my stat and it's quite different to his.
Mine works at 868.3 MHz and has a couple of chips in it:
The Atmel XMEGA128B1 which is the microcontroller and is here:
http://www.atmel.com/images/atmel-8330-8-and-16-bit-avr-microcontroller-xmega-b-atxmega64b1-atxmega128b1_datasheet.pdfThe second chip is an ATRF212 which is the wireless chip. It's essentially an SPI-to-wireless transceiver chip and is here:
http://www.atmel.com/images/doc8168.pdfNow for the bit where I'm stuck. I don't have much radio experience and want to buy a suitable receiver for it, then I can decode the transmission and work out the on and off codes. However, the ATRF212 supports a range of transmission standards and I have no idea which one it uses. I have a scope, but that's only 100MHz and a frequency counter that goes up to 1.3GHz but I don't think either are much help in this situation.
Interestingly, the ATRF212 is around £2.00, the XMEGA128B1 is around £3.70 and the stat costs £109.99. I think the manufacturer us making a killing with these...
You may think I've bitten off more than I can chew, and you may be right, but I was wondering if anyone could point me in the right direction?
I've attached some piccies of the stat for reference.
Thanks for reading.....
Steve