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Custom Electronics / BLE

ESP32 BLE Custom PCB Badge with RGB LEDs

A custom ESP32 board with BLE connectivity and 40 addressable RGB LEDs, running from either USB-C or an onboard LiPo cell.

Bat-shaped ESP32 badge PCB with purple solder mask, its perimeter RGB LEDs lit red, running from a connected LiPo cell
Assembled bat-shaped badge PCB showing the RGB LED ring, reference designators and I²C header footprints
The badge illuminated while connected to USB-C, with the LiPo cell attached, demonstrating power-path switching between USB and battery
The badge running an animated colour sequence, LEDs lit green

Engineering scope

  • Custom ESP32-based PCB with BLE connectivity and 40 RGB LEDs
  • USB-C charging with LiPo battery management
  • Stable 5V LED rail using a buck-boost converter, with a separate 3.3V MCU supply
  • Power-path switching resolved for seamless USB and battery operation
  • Design optimised for reliability and manufacturability (JLCPCB)

Design approach

The defining constraint was powering 40 RGB LEDs from a single cell without disturbing the MCU. A buck-boost converter holds the 5V LED rail steady as the battery discharges below 5V, while the ESP32 runs from its own 3.3V supply so LED switching currents stay off the MCU rail. Power-path switching was the problem worth solving: handing over between USB-C and battery without the LEDs glitching or the MCU resetting. The layout and component selection were kept within JLCPCB's assembly capabilities so the board could be manufactured without redesign.

Technical consultation

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