Fan-tastic Misuse of Raspberry Pi GPIO


(*11*)[River] is a huge fan of house automation. After transferring into a brand new area, he sought after to assimilate two wirelessly managed fan lighting into his house automation machine. The issue used to be this: despite the fact that the enthusiasts had been wi-fi, their frequency and protocol had been incompatible with the house automation machine.

(*11*)Step one used to be to resolve the frequency the fan’s far off used. Even if public FCC data will expose the frequency of operation, [River] idea it could be sooner to make use of an affordable USB RTL-SDR with the Spektrum program to comb the variability of most likely frequencies, and temporarily discovered the enthusiasts talk 304.2 MHz.

(*11*)Subsequent used to be to reverse-engineer the protocol. Common Radio Hacker is a device designed to make decoding unknown wi-fi protocols reasonably painless the use of an RTL-SDR. [River] digitized a button press with it and right away known it as easy on-off keying (OOK). With that wisdom, he digitized the radio instructions from all seven buttons and used to be temporarily ready to reverse-engineer all the protocol.

(*11*)[River] sought after to make use of a Raspberry Pi to deliver the enthusiasts into his house automation machine, however the Raspberry Pi doesn’t have a 304.2 MHz radio. What it does have is user-programmable GPIO and the rpitx bundle, which converts a GPIO pin right into a fundamental radio transmitter. After all, the Pi’s GPIO pin’s aren’t lengthy sufficient to successfully transmit at 304.2 MHz, so [River] added a right kind antenna, in addition to a low-pass clear out to wash up the transmitted sign. The rpitx bundle helps OOK out of the field, so [River] used to be temporarily ready get the Pi controlling his fan very quickly!

(*11*)In the event you’d care to do some extra cheap house automation, take a look at this solution to the use of a Raspberry Pi to keep an eye on some bargain-bin sensible plugs.