Flix

Flix (flight + X) — open source ESP32-based quadcopter made from scratch.

Features

• Dedicated for education and research.
• Made from general-purpose components.
• Simple and clean source code in Arduino (<2k lines firmware).
• Control using USB gamepad, remote control or smartphone.
• Wi-Fi and MAVLink support.
• Wireless command line interface and analyzing.
• Precise simulation with Gazebo.
• Python library.
• Textbook on flight control theory and practice (in development).
• Position control (using external camera) and autonomous flights¹.

¹ — planned.

It actually flies

See detailed demo video: https://youtu.be/hT46CZ1CgC4.

Version 0 demo video: https://youtu.be/8GzzIQ3C6DQ.

Usage in education (RoboCamp): https://youtu.be/Wd3yaorjTx0.

See the user builds gallery:

Simulation

The simulator is implemented using Gazebo and runs the original Arduino code:

Documentation

1. Assembly instructions.
2. Usage: build, setup and flight.
3. Simulation.
4. Python library.

Additional articles:

• User builds gallery.
• Firmware architectural overview.
• Troubleshooting.
• Log analysis.

Components

¹ — barometer is not used for now.
² — this frame is optimized for GY-91 board, if using other, the board mount holes positions should be modified.
³ — you also may use any transmitter-receiver pair with SBUS interface.

Tools required for assembly:

• 3D printer.
• Soldering iron.
• Solder wire (with flux).
• Screwdrivers.
• Multimeter.

Feel free to modify the design and or code, and create your own improved versions. Send your results to the official Telegram chat, or directly to the author (E-mail, Telegram).

Schematics

Simplified connection diagram

(Dashed elements are optional).

Motor connection scheme:

You can see a user-contributed variant of complete circuit diagram of the drone.

Notes

• Power ESP32 Mini with Li-Po battery using VCC (+) and GND (-) pins.

• Connect the IMU board to the ESP32 Mini using VSPI, power it using 3.3V and GND pins:

  IMU pin	ESP32 pin
  GND	GND
  3.3V	3.3V
  SCL (SCK)	SVP (GPIO18)
  SDA (MOSI)	GPIO23
  SAO (MISO)	GPIO19
  NCS	GPIO5

• Solder pull-down resistors to the MOSFETs.

• Connect the motors to the ESP32 Mini using MOSFETs, by following scheme:

  Motor	Position	Direction	Prop type	Motor wires	GPIO
  Motor 0	Rear left	Counter-clockwise	B	Black & White	GPIO12 (TDI)
  Motor 1	Rear right	Clockwise	A	Blue & Red	GPIO13 (TCK)
  Motor 2	Front right	Counter-clockwise	B	Black & White	GPIO14 (TMS)
  Motor 3	Front left	Clockwise	A	Blue & Red	GPIO15 (TD0)

  Clockwise motors have blue & red wires and correspond to propeller type A (marked on the propeller). Counter-clockwise motors have black & white wires correspond to propeller type B.

• Optionally connect the RC receiver to the ESP32's UART2:

  Receiver pin	ESP32 pin
  GND	GND
  VIN	VCC (or 3.3V depending on the receiver)
  Signal (TX)	GPIO4¹

¹ — UART2 RX pin was changed to GPIO4 in Arduino ESP32 core 3.0.

Resources

• Telegram channel on developing the drone and the flight controller (in Russian): https://t.me/opensourcequadcopter.
• Official Telegram chat: https://t.me/opensourcequadcopterchat.
• Detailed article on Habr.com about the development of the drone (in Russian): https://habr.com/ru/articles/814127/.

Disclaimer

This is a DIY project, and I hope you find it interesting and useful. However, it's not easy to assemble and set up, and it's provided "as is" without any warranties. There's no guarantee that it will work perfectly, or even work at all.

⚠️ The author is not responsible for any damage, injury, or loss resulting from the use of this project. Use at your own risk!