Posted by Updated on July 2, 2004
Brand name : ATECH, model WS303
Remote module : 2 * model WS303.
It turned out that a simple Telecontrolli receiver (I used a RR3-433 module) can receive the stream from the remote modules. I connected the module output to centronics, and make acquisitions using “Slogan” (simple logic analyser).
Frame format : let’s name a (low pulse + short high pulse) : “H”, and (low pulse + long high pulse) : “L”.
Then you can see on the snapshot : HHHHHHHH (pause) LLLLHHLL …
All “H” sequences are double, and except for the preamble, they are precedeed by a “L” sequence : it gives a logic “1”. A “L” sequence alone decodes as “0”.
After the preamble, the stream can be decoded as a 28 bits stream.
My own & dirty decoding code : thermo.c
Soon : decoding software for AVR.