ESP32 Flight Conroller

ESP32-S3 Custom Flight Controller

A custom-designed drone flight controller built from the ground up around the ESP32-S3 microcontroller. This project is a work-in-progress, covering everything from custom PCB design in KiCad to low-level sensor drivers and Web Serial 3D visualization.

Hardware Features

• Microcontroller: ESP32-S3-WROOM-1 (Dual-Core Xtensa LX7, 240MHz)
• IMU: Bosch BMI088 (6-axis accelerometer & gyroscope) via SPI
• Barometer: Bosch BMP388 via I2C
• Power System: Onboard TPS54331 buck converter (battery Vin to 5V) & AMS1117-3.3 LDO
• PCB: Custom 4-layer PCB designed in KiCad, hand-soldered SMD components.

Assembled PCB

Hardware Design Process

1. Schematic

The schematic was designed in KiCad and ordered as a 4-layer PCB from JLCPCB.

2. PCB Layout & Stackup

The layout was routed in KiCad with the following dedicated 4-layer stackup:

• Layer 1 – Top Layer (F.Cu): Primary signal layer used for component placement (ESP32-S3, IMU, Barometer) and high-speed SPI/I2C trace routing.
• Layer 2 – Inner Layer 1 (In1.Cu): Dedicated internal Ground Plane (GND) providing low-impedance return paths and EMI shielding for sensitive sensors.
• Layer 3 – Inner Layer 2 (In2.Cu): Dedicated Power Plane with split power zones distributing clean 3.3V and 5V power across the board.
• Layer 4 – Bottom Layer (B.Cu): Secondary signal and ground layer used for remaining routing and bottom-side thermal dissipation.

Bill of Materials (BOM)

Integrated Circuits & Active Components

Connectors & Switches

Passives Summary

• Capacitors:
  • 100 nF (0603) — 8 pcs (Decoupling for MCU, sensors, and regulators)
  • 10 nF (0603) — 2 pcs (Noise filtering / compensation)
  • 3.3 nF (0603) — 1 pc (Buck converter compensation loop)
  • 4.7 µF (0603) — 1 pc (Bulk decoupling)
  • 10 µF (0805) — 1 pc (LDO input/output stabilization)
  • 22 µF (0805) — 4 pcs (High-capacitance power rail smoothing)
• Resistors (all 0603):
  • 10 kΩ — 7 pcs (Pull-ups & boot mode configuration)
  • 4.7 kΩ — 2 pcs (I2C bus pull-ups for SDA / SCL)
  • 5.1 kΩ — 2 pcs (USB-C CC line pull-downs for 5V power negotiation)
  • 100 kΩ — 2 pcs (Voltage dividers & enable lines)
  • 30 kΩ — 1 pc (Feedback network)
  • 52.3 kΩ — 1 pc (High-precision feedback resistor for buck regulator)

Software / Firmware

The firmware is written in C++ (Arduino framework) and features:

• Raw SPI Communication: Bypasses bloated libraries to communicate directly with the BMI088 registers, resolving complex ESP32 HAL macro conflicts.
• Sensor Fusion: Implements a custom Complementary Filter combining high-speed gyro data with accelerometer gravity vectors for stable, drift-free Pitch and Roll calculation.
• Barometric Altimeter: Features an auto-zeroing routine on startup to establish local ground-level pressure before calculating relative altitude in meters.

3D Web Visualizer

Included in the tools/ directory is a custom HTML5/Three.js 3D drone visualizer. It uses the modern Web Serial API to connect directly to the flight controller via USB (no servers required) and renders the drone's orientation in real-time at 60fps based on the live IMU telemetry.

Directory Structure

• hardware/: KiCad schematics and PCB layout files.
• firmware/FlightController/: The main C++ Arduino sketch containing sensor drivers and mathematical filters.
• tools/: Contains 3D_Viewer.html (Double-click to open in a modern browser).

Roadmap / To-Do

• PCB Design & Assembly
• I2C & SPI Bring-up
• Raw IMU & Barometer Data Extraction
• Sensor Fusion (Complementary Filter)
• Real-time 3D Visualization
• PID Controller Implementation
• ESC Motor Output (DSHOT/PWM)
• Radio Receiver Integration (ExpressLRS/Crossfire)

Hardware designed from scratch by Max. Firmware and 3D visualization developed using AI-assisted pair programming.