How to Set Up ExpressLRS on a Fixed Wing with PWM Outputs

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Introduction to ExpressLRS for Fixed Wings

ExpressLRS (ELRS) is a popular open-source radio control link that offers long range and low latency, perfect for fixed-wing enthusiasts and DIY makers. Setting up ELRS with PWM outputs lets you connect the receiver to your flight controller or servos easily, making it a great choice for fixed-wing aircraft. This guide walks you through installing and configuring ExpressLRS on your fixed wing using PWM outputs.

What You'll Need

  • ExpressLRS compatible receiver (e.g., Happymodel EP1, BetaFPV ELRS RX)
  • Compatible transmitter module or ELRS radio
  • Flight controller with PWM input support or servo connections
  • Soldering tools and wires for connections
  • ELRS Configurator software installed on your PC
  • Battery and your fixed wing model

Step 1: Flash Your ELRS Receiver

Before installation, you need to flash the correct ELRS firmware on your receiver. Download the ELRS Configurator from the official GitHub page or website.

  • Connect your receiver to your PC using a USB programmer or through a UART to USB adapter.
  • Open ELRS Configurator and select the correct hardware version of your receiver.
  • Choose the appropriate firmware version (usually the latest stable release).
  • Configure settings such as binding phrase and output mode (choose PWM output).
  • Flash the firmware to your receiver.

Step 2: Wiring the Receiver to Your Fixed Wing's Flight Controller

Once flashed, you need to connect the receiver to your flight controller or servos using PWM outputs. PWM works by sending pulse signals for each channel separately.

  • Identify the PWM output pins on your ELRS receiver (usually labelled CH1, CH2, etc.).
  • Connect each channel output to the corresponding PWM input on your flight controller or directly to servos if you’re not using a flight controller.
  • Make sure to connect the ground (GND) and power (usually 5V or 3.3V) lines as well.
  • Double-check polarity to avoid damaging components.

Step 3: Bind Your Receiver to the Transmitter

With wiring done, it’s time to bind the receiver to your transmitter module or radio.

  • Power up the receiver while holding the bind button or shorting bind pads (depending on your receiver).
  • Put your transmitter module into bind mode via the ELRS interface.
  • Wait for the receiver LED to indicate a successful bind (usually a solid light).
  • Exit bind mode on the transmitter and power cycle both devices.

Step 4: Configure Your Flight Controller

If you use a flight controller, you’ll need to tell it to accept PWM inputs from the ELRS receiver.

  • Connect your flight controller to your PC and open your configuration software (e.g., Betaflight Configurator, INAV Configurator).
  • Set the receiver mode to PWM (also called PPM in some setups, but ELRS PWM receivers output separate signals per channel).
  • Map the channels correctly (Throttle, Aileron, Elevator, Rudder, etc.) to match your transmitter setup.
  • Test the controls to confirm correct response.

Tips for a Smooth Setup

  • Keep your wiring short to reduce signal noise.
  • Use heat shrink tubing or electrical tape to secure solder joints.
  • Double-check that your receiver voltage matches your flight controller or servo requirements.
  • Perform a range test in an open area before flying.

Conclusion

Setting up ExpressLRS on a fixed wing using PWM outputs is a straightforward process that delivers a robust and reliable control link. With the open-source flexibility of ELRS and the simplicity of PWM wiring, you can enjoy excellent range and responsiveness for your flights. Happy flying, and enjoy your DIY project!

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