IKEA Ansluta 433 MHz remote on/off switch reverse engineering
This is my humble attempt at analyzing and replicating the transmissions of the IKEA Ansluta remote on/off switch. (Note: There are at least two different versions of this remote; this is about the simple switch without dimming.)
- find transmitter on the PCB
offtransmissions at the source
- figure out the code (optional)
- replicate the code with own transmitter
Finding the transmitter
Unfortunately I’m no electrical engineer, far from it: I’m utterly clueless. Let’s just open this thing up and have a look. I have another 433 MHz remote control for reference.
The reference remote is extremely simple: an 18 pin IC labelled
HX2262, a led, a few switches and button pads, and the crystal oscillator (round metal package) labelled
The Ansluta is more crowded, but we see a 16 pin IC, this time labelled Holtex
HT48R06A-1, and a crystal (oblong metal package) labelled
T13.560 – I’m not sure whether there’s any significance to the fact that this is not a 433 MHz crystal.
After trying a few of the IC’s pins I see that a led attached to pin 5 (bottom row in the picture) flickers suspiciously when pressing the
off buttons — this must be it.
Capturing the signal (and possibly decoding it)
Here’s what I got from that pin (when pressing
on) — this was repeated seven times:
Looks good, doesn’t it? An initial long
sync pulse followed by a sequence with nice even spacing of about half a ms. More precisely, the periods of
high voltage are slightly under half a ms, while a (single)
low is slightly longer:
Let’s call them
0 bits (even though they’re not) until the coding is figured out. Then the sequence looks like this:
100000000000000000000000000000000000(1 + 35 bits), then
Okay, I feel slightly uncomfortable with this because of the uneven lengths, but clearly it’s a sequence of
100s. So let’s call those
0, yielding this shorter representation:
Notice that all but the last eight bits are identical, and that those eight bits are precisely inverted:
01 (times four) for
10 for off.