The company Free Wili was providing LED bracelets with custom printing on them advertising their new flipper-but-better device Free Wili. Here are notes from taking it apart. Initially the goal was take it apart because I could not believe it would just be an LED bracelet and that's it. Once I saw the radio receiver, I then wanted to figure out what sort of signals could control this bracelet.
- CMT2220LS
- OOK Receiver that mostly works at 433.92 Mhz
- https://crossic.com/wp-content/uploads/2022/02/CMT2220LS-Datasheet-EN-V1.0-20210917.pdf
- Markings-scrubbed SOP 8 IC
- Clearly the brains of the operation though, given central location
- 13.52127 MHz crystal
- 2x CR2032 battery
- 2 Multi-color LEDs
- A button
The PCB has the text:
HE-B158ST1K1
on it. When you search that, it'll show a few sites for Xyloband that is used at some concerts and events, as well as some of the shopping sites that re-sell this. Nothing too useful for this though.
The battery is interesting because the positive side is connected to the board through a coil/spring wrapped around a mounting hole.
There is no "off-state". If the batteries are connected, the device is powered. When the LEDs aren't running, the device is still on, running at 5-5.5v.
The DOUT of the radio IC connects to pin 3 of the unmarked IC.
Best I can tell, this is what the pins are.
Could not determine what the chip was. Interfacing with it is likely done on pins 2 or 3 though.
Pin 2 goes low occaisonally and shortly after Pin 3 has a bunch of signals.
The Pin 2 stays low for ~162.400 ms (+/- 0.005) and then bounces back up. In one instance, it went low for 162.400 ms, then went high. Pin 3 stays mostly low but goes high every 40-50 us. Then 26.602 ms later, Pin 2 goes low for 132.130 ms.
Free Wili posted the Flipper format .sub files to control the LEDs in this repo.
I'm reasonably certain these were given away so that people who bought the Free Wili board or the Whale Tail had some things to mess with: namely people wearing the LED bracelets. Pretty clever!