STM32 Ranger TX

A custom RC transmitter project based on STM32F4 microcontroller, implementing the CRSF (Crossfire) protocol for RC control.

Features

• Control Channels:

  • 4 main control channels (Aileron, Elevator, Throttle, Rudder)
  • 8 AUX channels for additional functions
  • Configurable stick offsets and reversals
  • Simple Moving Average (SMA) filtering for smooth control

• CRSF Protocol:

  • Full CRSF (Crossfire) protocol implementation
  • Configurable packet rates (50Hz to 500Hz)
  • Adjustable power output (10mW to 250mW)
  • Dynamic power control
  • Model matching capability
  • WiFi connectivity for updates

• Safety Features:

  • Battery voltage monitoring
    • Warning at 7.4V (2S LiPo)
    • Critical at 7.0V
    • USB power detection at 5.2V
  • Stick movement detection with timeout warning
  • Configurable failsafe settings

• User Interface:

  • Audio feedback through passive buzzer
  • Startup melody
  • Stick movement warning melody
  • Multiple power/rate settings accessible through stick combinations

Hardware Requirements

• STM32F4xx microcontroller
• 4 analog inputs for control sticks
• Multiple digital inputs for switches
• Passive buzzer for audio feedback
• Battery voltage monitoring circuit
• UART interface for CRSF communication

Configuration

Stick Commands

The transmitter supports special stick combinations for configuration:

• Up Left: Rate/Power setting 1 (250Hz / 100mW / Dynamic)
• Up Right: Rate/Power setting 2 (50Hz / 100mW)
• Down Left: Start TX bind
• Down Right: Start TX module WiFi

Power Settings

Two default configurations:

1. Setting 1:

   • Packet Rate: 250Hz
   • Power: 100mW
   • Dynamic Power: On

2. Setting 2:

   • Packet Rate: 50Hz
   • Power: 100mW
   • Dynamic Power: Off

Building and Flashing

1. Clone the repository
2. Open the project in STM32CubeIDE
3. Build the project
4. Flash to your STM32F4 device

Dependencies

• STM32 HAL Library
• CRSF Protocol Library
• Standard C Library

License

This project is licensed under the GNU General Public License v3.0 - see the LICENSE file for details.

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

Acknowledgments

• Based on the CRSF protocol implementation
• Inspired by the work of kkbin505: https://github.com/kkbin505/Arduino-Transmitter-for-ELRS
• Uses STM32 HAL libraries for hardware abstraction