AeroHawk FC

The Eagle: Custom STM32F405 Autonomous Flight Controller

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The Eagle is a custom, 4-layer high-reliability avionics flight controller (FC) designed around the STMicroelectronics STM32F405RGT6 microcontroller. Engineered for autonomous Unmanned Aerial Vehicles (UAVs) and high-performance robotics platforms, the board integrates high-bandwidth IMU telemetry, multi-stage power conditioning, blackbox high-rate logging, and deterministic motor signaling into a 40.0 × 40.0 mm board footprint with a 34.0 × 34.0 mm mounting hole pattern.

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3D Isometric View

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Hardware Gallery & Subsystems

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Engineering Highlights & Key Specifications

1. Compute & Core Architecture

• Primary MCU: STM32F405RGT6 (ARM Cortex-M4 with single-precision FPU, 168 MHz core clock, 1 MB Flash, 192 KB SRAM).
• Clocking: External 8.000 MHz crystal oscillator feeding the internal PLL for zero-jitter core timing and USB 48 MHz generation.
• Programming & Debug: Onboard 4-pin SWD header (3V3, SWDIO, SWCLK, GND) for ST-Link / J-Link debugging and automated CI flashing.
• Boot Management: Hardware BOOT and RST tactile buttons supporting USB DFU system recovery.

2. Sensor Suite & Signal Integrity

• Primary IMU: TDK InvenSense ICM-42688-P 6-axis MEMS gyroscope/accelerometer on a dedicated high-speed SPI1 bus (up to 20 MHz).
• Interrupt Routing: Dedicated hardware EXTI Data-Ready (DRDY) interrupt line tied directly to the MCU NVIC for deterministic 8 kHz loop timing.
• Barometric Altimeter: Bosch Sensortec BMP390 precision pressure sensor on I2C1 for sub-meter altitude hold.
• Blackbox Storage: Winbond W25Q128JVSSIQ (128 Mbit / 16 MB) SPI NOR Flash on SPI3 for high-rate loop and telemetry logging.
• Bus Isolation: SPI and I2C signal traces are referenced directly to an unbroken Layer 2 Ground Plane to suppress crosstalk and high-frequency noise.

3. Power Distribution Network (PDN)

• Battery Input: 3S–6S LiPo input (9.0V to 26.0V nominal; rated up to 36V transient tolerance).
• Transient Voltage Suppression (TVS): Onboard SMBJ28A high-energy TVS clamp at the main battery junction to suppress motor inductive voltage spikes.
• Reverse Polarity Protection: P-channel MOSFET gate protection preventing accidental battery reverse-connection damage.
• Synchronous Buck Converter: Texas Instruments LMR51430 step-down regulator delivering clean 5.0V @ 3.0A for receivers, telemetry, and peripheral rails.
• Ultra-Low-Noise Sensor LDO: Texas Instruments TLV75733PDBV (3.3V @ 1.0A) high-PSRR linear regulator exclusively isolating the analog sensors and MCU core.
• Analog Telemetry: Low-pass RC filtered 11:1 voltage divider (VBAT_SENSE) and ESC analog current input (CURR_SENSE).
• USB Interface: Micro-USB / USB-C pads protected by ST USBLC6-2SC6 ultra-low capacitance bidirectional ESD suppressor.

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Silicon Registry & Pin Allocation Matrix

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PCB Stackup & Fabrication Rules

• Dimensions: 40.00 mm × 40.00 mm outer footprint
• Mounting Pattern: 34.00 mm × 34.00 mm grid (M2 mounting pads)
• Layer Count: 4 Layers (Standard 1.6 mm FR-4 Stackup):
  • Layer 1 (Top): Component placement & High-Speed Signal routing
  • Layer 2 (Inner 1): Solid Ground Plane (GND) for low return-loop inductance
  • Layer 3 (Inner 2): Power Plane split (5.0V / 3.3V power distribution)
  • Layer 4 (Bottom): Power Switching Stages, ESC pads, and secondary signal traces
• Minimum Trace / Space: 0.15 mm / 0.15 mm (6 mil / 6 mil)
• Minimum Drill: 0.3 mm (via size: 0.6 mm outer diameter)
• Design Rule Check (DRC): 0 Errors, 0 Unconnected Nets

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Manufacturing & Project Deliverables

All production assets are pre-generated and included in this repository:

• 📄 Schematic (PDF): schematic/TheEagle_Schematic.pdf
• 📐 Schematic (SVG): schematic/TheEagle_Schematic.svg
• 📦 Fabrication Gerbers & Drill (ZIP): manufacturing/TheEagle_Gerbers_Rev1.zip
• 📋 Bill of Materials (BOM CSV): manufacturing/TheEagle_BOM.csv
• 💻 KiCad Source Files: Located in hardware/

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Firmware Compatibility

The hardware layout and pin allocation strictly adhere to the STM32 timer and peripheral mapping required by standard flight controller firmware:

1. ArduPilot (ChibiOS): Fully compatible via standard ChibiOS hwdef.dat board definition.
2. Betaflight / INAV: Compatible using STM32F405 target configuration with DShot DMA timer assignment.
3. Custom Bare-Metal C++ / MATLAB Simulink: Direct code generation via Embedded Coder / HAL drivers using the onboard SWD debug interface.

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How to Open in KiCad

1. Clone this repository:

   git clone https://github.com/sbbxiii/The-Eagle.git
   cd The-Eagle/hardware

2. Open AeroHawk_FC.kicad_pro using KiCad 8.0 or newer (tested on KiCad 10.0).
3. View schematics in Eeschema or board layout in Pcbnew.

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Author & License

Designed by Osakwe Nmesoma Chukwukadibia, Bsc Engineering Student University of Debrecen.

Licensed under the MIT License.