Paul__B:
Actually, it appears that with the PT2262/PT2272 chip pair, the four buttons correspond to four separate data bits which are transmitted together and independently decoded at the receiver as a four-bit "word" (nybble) with sixteen possible values.The encoder transmits continuously when powered, even if all data bits are zero, and the decoder generates a "Valid data" signal to indicate it is actually receiving the data.
There is no reason you cannot use these to send four data bits continuously (or in bursts) over a single signal wire as an alternative to a wireless channel.
I have some of these on hand, so I tried it out.
The behavior seems to be that if a button is pushed, the others are effectively locked out. That is, the corresponding pin on the receiver goes active and pushing other buttons on the fob has no effect. If multiple buttons are pushed simultaneously, all corresponding pins on the receiver go active and the inactive buttons on the fob are effectively locked out. When I have more time, I'll try and look at the serialized waveform, but my guess is that it's sending only one code at a time, but that code may have multiple channels activated.
The net seems to be that PT2262/PT2272 supports multiple simultaneous channels, but doing so from the key fob would be awkward for the thread scenario as I understand it.
