Wire one 130mm or 300mm 3v n00d to your battery holder as shown. To figure out which is the + and - end of the n00d, press the two sides against your coin cell battery for a moment. If it lights up, you've got it right. If not, flip the battery over and try again.
If you're using two or three n00ds on your mask, you'll need two or three battery holders. It's tempting to try connecting two n00ds to a double coin cell holder but you'll get unreliable behavior and flickering.
One battery, one n00d.
This setup uses the AW9523 GPIO expander board with a Feather microcontroller to run up to 16 n00ds from a single battery. I used the Feather RP2040 PropMaker because I wanted motion sensing, but just about any Adafruit Feather controllers will work.
Plug the Feather RP2040 PropMaker into the AW9523 breakout using your Stemma QT cable.
The n00ds can connect to any of the GPIO pins on the AW9523. The + side goes to the VIN pin and the - side to the numbered pin. The sample code uses pins 0, 1, 2, 3, 9, 10, and 11 but this is easy to change to match your setup.
The battery will plug directly into the JST port on the Feather, and the on/off switch will go inline with the red battery cable.
Page last edited March 05, 2026
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