Electronics Assembly
Solder four short (1" / 2.5cm) wires from the Feather to the back of the matrix as shown:
- +5v to BAT
- GND to GND
- DIN to A0 (aka 26)
- CIN to A1 (aka 25)
Next we'll add the power switch. Cut the red wire on the battery cable right in the middle. Strip a little bit of shielding off each side and add a little piece of heat shrink onto each wire.
Prepare your switch: cut one of the side legs off so it's out of your way. Bend the remaining wires outwards a bit -- we'll bend them down more once they're wired up.
With the switch in the "off" position (the slider positioned above the leg you just cut off), solder the two remaining switch legs to the battery cables. Cover with heat shrink.
With this configuration, the necklace must be switched ON in order to charge the battery. If the necklace is switched off, there's no physical connection between the battery and the board so charging won't happen.
Plug the battery in to the JST connector on the Feather and flip the switch to the "on" position. If all goes well, your matrix should light up with all yellow lights. Success!
If not, here are a few things to try:
Troubleshooting
- Make sure you soldered to the IN pins on the matrix and not the OUT pins. You want the ones labeled CIN and DIN.
- Head to the WLED interface and open LED preferences. Make sure everything matches the graphic and your GPIO pins are correct.
- It's very easy to switch the GPIO pins for the clock and data lines (CIN and DIN). Try switching the numbers 25 and 26 and see if that fixes things.
- Make sure there are no stray wires shorting between any of the pins.
- Try uploading / installing the software again if you're having trouble.
Page last edited February 03, 2026
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