My home automation network has grown to 44 devices comprising both manual and timed transmissions which may be single-character or multi-byte messages. All contain micro-controllers.
They form a mesh with various interoperability regimes. Transmissions are asynchronous at 2400 baud and last less than 100 milliseconds. The protocol used totally prevents false activation, but there are missed messages, They all use the same $5 Radiotronics transmit and receive modules.The RF components use AMK (ON-OFF) keying in the 433.92 MHZ ISM band, which may have a range up to 1 Km.The main problem to be solved is the frequent bursts from other sources, and the continual noise pulses from the receiver. All use the same unlock code at the beginning of the message.
These transmitters provide on-off for outlets with lights, and some select the display mode for controllers which show information.
The On-off message have a single control byte, while the display select message have a two bye control sequence, with the first byte being “O”.
ty have short bursts with a format which may be used for any of the receivers. Unlike the RF Control messages, these messages have a two-character checksum at the end.
