This is a custom flight controller board built around the STM32F722RET6 (LQFP-64), designed as a from-scratch alternative to commercial ArduPilot/Betaflight-compatible boards. I wanted full control over the peripheral map and sensor selection rather than working around an off-the-shelf board's constraints, and to actually understand every design decision that goes into a flight controller not just fly one.

Why I built it

I'm running ArduCopter firmware and building a companion Qt/C++ ground control station in parallel, so I wanted a board whose I/O layout and sensor set I fully understand and control end to end hardware, firmware, and GCS.

How it works

• MCU: STM32F722RET6, 216 MHz Cortex-M7, plenty of headroom for EKF and control loops
• IMU: ICM-42688-P (SPI) high-performance 6-axis gyro/accel for the primary EKF lane
• Barometer: BMP390 for altitude estimation
• Magnetometer: LIS3MDL for heading reference
• EEPROM: M24C02 for calibration/parameter storage
• USB: USB-C receptacle with USBLC6-2P6 ESD protection, straight into the F722's native USB peripheral for GCS connection and DFU flashing
• Storage: microSD slot for onboard logging
• Power: TLV75533 LDO regulation, with ferrite bead filtering and a mix of 100nF/1–10uF decoupling across all rails
• UI: 4 status LEDs (blue/green/yellow/red) plus 2 push buttons (boot/reset)
• Timing: SIT1602AI MEMS oscillator instead of a traditional crystal, for vibration tolerance

Board build

• 4-layer stack (signal / power plane / power plane / mixed plane), routed and DRC-checked for PCBWay's standard manufacturing capabilities. Designed in KiCad 10.
• The hardware is designed to support both a custom firmware and ArduCopter compatible firmware.

This flight controller is intended as an open and flexible development platform, making it well suited for:

• Academic research and experimentation
• University coursework and student projects
• Firmware development and control algorithm testing
• Custom UAV, robotics, and embedded control systems

With its compact form factor, accessible interfaces, and research-focused design, this board serves as a reliable foundation for both learning and advanced prototyping.

Project & Author Links:

• GitHub: https://github.com/SyntaxKavindu
• LinkedIn Profile: https://www.linkedin.com/in/kavindu-chamath-0b70602a5/