AtmosFC

AtmosFC is an open-hardware quadcopter flight controller designed in KiCad. Powered by an STM32G4 MCU, it integrates high-performance sensors and peripherals, and is fully compatible with Betaflight (≥ 4.5).

Table of Contents

• Features
• Input / Output
• Hardware Architecture
• Flashing Betaflight
• Notes
• Gallery
• Repository Structure
• License

Features

• MCU: STM32G473CEU6
• IMU: ICM-468-P
• Barometer: DPS-386
• OSD: MAX7456 for analog on-screen display
• Blackbox: 32MB onboard flash memory for log recording
• Power input: Up to 6S
• Power monitoring: Battery voltage and current sensing
• Status indicators: Green, Blue, and Amber LEDs
• Dimensions: 40x40mm
• Mounting holes: 30.5×30.5 mm (M4 holes for silicone inserts with M3 screws)
• Weight: 8.2g

Input / Output

• USB connector: USB Type-C
• Motor outputs: x4
• ESC: Current sensing and telemetry
• UARTs: x3
• I2C: Yes
• Video Input / Video Output with OSD
• 5V outputs: up to 3A total
• Buzzer output

Hardware Architecture

The block diagram below shows the main hardware components and their interconnections.

Flashing Betaflight

AtmosFC runs Betaflight ≥ 4.5. You can either flash the precompiled Betaflight 4.5 firmware or build the latest from source.

Option 1 – Using the provided firmware

1. Open Betaflight Configurator.
   If you don’t have it installed, get the latest version here : Betaflight Configurator Releases
2. Connect AtmosFC via USB-C.
3. If required, enter DFU mode (hold the BOOT button while plugging in USB).
4. In the Betaflight Configurator, go to Firmware Flasher → Load firmware [Local] and select the file betaflight_4.5.0_ATMOSFC.hex in betaflight_config/.
5. Click Flash Firmware and wait for the board to reboot.

Option 2 – Building from Source

1. Clone the Betaflight Repository and install the required toolchain. Follow the official setup guide for your OS : Betaflight Building Docs.
2. In the Betaflight root directory, update the target list by running:

> make configs

3. Add the AtmosFC board configuration by copying the folder betaflight_config/ATMOSFC/ into betaflight/src/config/configs.
4. Build the firmware for AtmosFC target.

> make ATMOSFC

5. The compiled .hex file will be located under betaflight/obj/. Flash it using Betaflight Configurator (follow the steps from Option 1).

Notes

• The board has been successfully tested with Betaflight 4.5. All basic functions, including motor outputs, sensors, LEDs, were working correctly.
• I did not test the OSD feature, as I was flying using digital FPV goggles instead of analog video.
• There is a small voltage drop on the VBAT measurement (~0.2-0.3V) due to the Schottky diode used for reverse polarity protection.
  • This can be compensated either by applying a software offset in Betaflight, or by using an alternative reverse polarity protection method, such as a MOSFET-based circuit

Gallery

Repository Structure

The repository is organized as follows:

├── hardware/             
│   ├── atmos_fc/           # KiCad project files (.kicad_pcb, .sch, etc.)  
│   ├── assembly/           # Fabrication files (Gerber, BOM)
│   └── lib/                # Custom footprints, symbols, 3D models
├── betaflight_config/
│   ├── ATMOSFC/            # Board configuration for Betaflight ≥ 4.5
│   └── betaflight_4.5.0_ATMOSFC.hex    # Precompiled Betaflight 4.5 firmware
├── documentation/          # Schematic (.pdf), images, logo, block diagram
└── README.md

License

This project is released under the MIT License.
You are free to use, modify, and distribute it.