Interfacing with radio controlled mains sockets - part 2

nospam@example.com (Fanjita) — Sat, 31 Mar 2012 23:39:14 +0100

My last post discussed receiving and decoding signals from the Maplin socket controller. Here, I'll describe how I went the opposite way - faking the signal to control the sockets directly with an Arduino.

As it turned out, this was a lot simpler than receiving. For one thing, the transmitter module is just 4 pins rather than 8, and can be directly driven from the Arduino with no further components. For another, I already had a representation of what the signal needed to look like - I just had to drive the transmitter input pin with the right timings.

So, here's some trivial code to do just that - it turns channel 3, ID 2 on for 3 seconds, then off for 10 seconds, repeatedly. The transmitter module plugs directly into analogue pins A3-A5, as shown in the photo. The antenna pin is left unconnected for the time being - in practice, you'd probably want to connect a suitable antenna (or just a short piece of wire, as per the data sheet) to get optimal range.

Continue reading "Interfacing with radio controlled mains sockets - part 2"

Interfacing with radio controlled mains sockets - part 1

nospam@example.com (Fanjita) — Thu, 29 Mar 2012 23:17:00 +0100

Maplin have recently had special offers on remote-controlled mains sockets - as cheap as £5 for a socket and controller pair. Since the control frequency is on the standard 433MHz band, and I had a pair of Arduino-friendly 433MHz transmitter/receiver modules lying around, I thought I'd have a play to see if the control protocol can easily be reverse-engineered for use with the Arduino.

So, I dutifully hooked the receiver module up to 5V and an oscilloscope, and started pressing buttons on the controller. Things looked promising - a simple ASK pulse train, probably Manchester encoded.

A single data packet. Not shown is the leading low pulse between each packet - approx 13ms.

Continue reading "Interfacing with radio controlled mains sockets - part 1"

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Interfacing with radio controlled mains sockets - part 2

Interfacing with radio controlled mains sockets - part 1