DIY Quadcopter Firmware Runs 400Hz Control Loop on $5 ESP32-S3

A new paper from researchers Ad-Deen Mahbub, Indroneel Roy, and Mohammad Kamruzzaman Khan Prince details the design and optimization of quadcopter firmware for the low-cost ESP32-S3 microcontroller. The firmware leverages the chip's dual cores with strict task allocation: Core 1 runs a 400Hz control loop that fuses sensor data using a Madgwick filter and implements a hybrid fixed-point PID controller enhanced with selective derivative scaling and feedforward braking for precise stabilization. Core 2 handles 50Hz telemetry encoding and real-time UDP-based video streaming at 25FPS VGA resolution, keeping control and communication workloads separated to prevent latency interference. Inter-core communication uses zero-copy buffers with mutex protection to minimize overhead, and a custom event-driven threading model with RTOS-inspired static scheduling ensures deterministic execution and jitter-free operation.

The experimental evaluation confirms that this firmware architecture provides stable flight and robust telemetry support despite the ESP32-S3's limited memory and floating-point performance. The entire system operates on a microcontroller that costs around $5, making it accessible for DIY projects and academic research. The paper is 6 pages with 12 figures and is available as a preprint on arXiv (2607.23220). This work demonstrates that sophisticated UAV control and video streaming can be achieved on ultra-low-cost hardware, potentially democratizing drone research and enabling fully customizable, open-source quadcopter designs for hobbyists and researchers alike.