Description

KiCad project for a custom, battery-powered doorbell with dual-color LED feedback and 4-layer circular PCB design. Optimized for low power and compact integration

README

Light Doorbell Hardware

This repository contains the KiCad design files (schematics and 4-layer circular PCB) for the Light Doorbell prototype: a battery-powered, LED-signaling doorbell based on a STM32L051K8T6 microcontroller and RFM69HCW 433 MHz radio module.

A light doorbell is useful in many situations: notifying a user wearing headphones, assisting people with hearing impairments, or simply providing a silent visual alert...

Overview

The prototype operates both as a transmitter and receiver.
When the central button is pressed, it sends a coded message to another board listening on the same frequency. Upon receiving the message, the board flashes its dual-color LEDs, green or red, depending on the battery level.

The device is rechargeable via a USB-C connector, and works with a range of several tens of meters in open space.

PCB 3D view

Features

Ultra-low-power STM32L051K8T6 ARM Cortex-M0+, 64 KB Flash, 8 KB RAM
RFM69HCW 433 MHz transceiver module
Li-ion / Li-po battery charger and management IC
3.0V LDO voltage regulator to step down USB or battery voltage
Load sharing circuit to seamlessly switch power source between USB and battery
Battery voltage monitoring
433 MHz helical antenna
Dual-color LEDs, green and red for visual feedback
USB-C connector for charging
Large mechanical push-button
10-pin ARM SWD debug / programming port
UART port for optional serial communication
Multiple test points and jumpers for current measurements, debug, and isolation
Designed for hand soldering and easy prototyping
Optimized for low power consumption

The current version focuses on development and testing. A future version could be further miniaturized by removing debug features and using smaller components...

Demo GIF

light-doorbell-hw

@estylos