LED Bracelet

Single-cell LED Bracelet controlled by ESP32-C3.

While the bracelet/collar can work in "standalone" mode, it is recommended to connect it to other device using BLE.

This board is untested.

Designed to be manufactured by JLCPCB as 4layer PCB with both inner layers acting as GND (you can probably use just the outer layers).

Features

5V LED strip
- Designed for WS2812 LEDs (=digital signal)
5V LED filament (outline)
- Most of those filaments are 3V so use two of them, 2.5V should be enough
- Can use PWM for brightness control
USB-C charging
- 5V 1.5A max (5.1k resistors)
- TP4056 charger
  - Status LEDs
    - Red = Charging
    - Blue = Standby
  - 1S 1A charging (1 cell in series, unlimited in parallel)
- 1.5A discharge (DW01A)
- Voltage measurement
  - 3/4 of voltage
  - Max 4.4V (=don't connect to 5V / USB)
ESP32-C3 controller
- BLE controls
- Mode button to cycle colors
- BOOT jumper pads (instead of a button)

There are no reverse-polarity protections
There are no fuses, you are responsible for maximum current on 5V output(s)
- 1.2A shared between LED Strip and LED Filament connectors
  - max 20 RGB LEDs as 20*3*20mA = 1.2A (3 as the current is for each LED of RGB)
Highlighted traces on silkscreen show voltages to measure (for testing)
Some components are not in component placement
- Use any 1206 LEDs (recommended colors are on silkscreen)
- Mode button may need an uncommon component
- Any THT connectors (battery + pin headers)
Some components may need rotation tweak for fabrication
- All U and Q components may need a rotation change (align 1st pin with long line on silkscreen)
- L1 needs 90deg rotation

Implement logic for BLUETOOTH_ON_NO_CLIENT_WAIT
- Wait X seconds after turning the BLE ON, then turn it OFF if no client connected in the meantime
Turn bluetooth OFF on critical battery level (and prevent it from turning on)
- Compile define to disable this behavior
- Add "What happens on Battery Critical?" section to FAQ
Compile define to independently disable Deep Sleep