DingDong - Smart Doorbell System

DingDong is a privacy-focused smart doorbell designed to eliminate cloud subscription dependency while reducing false motion alerts through dual-sensor validation. Many commercial doorbells store video in the cloud behind recurring fees and generate frequent alerts due to single-sensor motion triggers which creates notification fatigue and raises privacy concerns. DingDong performs event detection and video storage locally using an ESP32-S3 development kit module, an OV5640 camera module, PIR sensing for thermal presence, mmWave radar for motion and distance confirmation, and a microSD card for on-device clip storage. Sensor fusion confirms a motion event only when both modalities agree, improving reliability before initiating buffered clip capture and notifying the user. The power subsystem converts a 5 V USB-C input to a regulated 3.3 V rail using a TPS54331 buck converter, sized using worst-case current budgeting and headroom margins to avoid brownouts during Wi-Fi transmission and camera activity. Firmware is organized with FreeRTOS tasks for sensing, capture, storage, and networking, while a Flutter-based mobile application provides local notifications, device setup, and access to stored clips without requiring cloud services.