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

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Introduction

If you’re a hobby RC pilot or maker in the UK looking to get the best out of your fixed-wing aircraft, setting up ExpressLRS (ELRS) with PWM outputs is a fantastic way to boost your control range and reliability. ExpressLRS is an open-source, high-performance radio link system that’s becoming popular thanks to its low latency and long range.

This guide will walk you through the process of setting up ELRS on a fixed wing, focusing on using PWM outputs for your receiver. Whether you’re upgrading an older plane or building from scratch, this will help you get flying with confidence.

What You’ll Need

Before you start, make sure you have the following:

  • An ELRS-compatible receiver with PWM output pins (e.g., Happymodel EP1 or BetaFPV ELRS RX with PWM)
  • A compatible ExpressLRS transmitter module or a radio with an ELRS module
  • A fixed-wing aircraft with a flight controller or a simple PWM servo setup
  • Battery and standard RC servos for your control surfaces
  • Access to a computer with USB ports for flashing firmware
  • ExpressLRS Configurator software installed on your PC or Mac

Step 1: Flash the Firmware

First, you need to flash the correct ELRS firmware onto your receiver and transmitter module. Here's how:

  • Download and install the ExpressLRS Configurator from the official GitHub or website.
  • Connect your receiver to the PC using a USB to UART adapter or via the built-in USB port if available.
  • Open the Configurator and select the correct receiver type and hardware version.
  • Choose the PWM output mode in the firmware options.
  • Build and flash the firmware to your receiver.
  • Repeat the process for the transmitter module, selecting the matching settings.

Note: Always double-check that your firmware versions and settings match on both ends to ensure smooth binding and operation.

Step 2: Wiring the Receiver to Your Fixed Wing

With the firmware ready, it’s time to connect the receiver to your plane:

  • Identify the PWM output pins on your ELRS receiver – usually labelled as CH1, CH2, CH3, and so on.
  • Connect each PWM output pin to the corresponding servo input on your flight controller or directly to servos if you’re not using a flight controller.
  • Ensure the receiver’s ground and power pins are connected properly to your plane’s power distribution board or ESC BEC (Battery Eliminator Circuit).
  • Double-check polarity and connections to avoid damage.

Step 3: Binding the Receiver and Transmitter

Binding pairs your transmitter and receiver so they can communicate:

  • Power on the receiver while holding its bind button (if present) or follow the binding procedure specific to your receiver model.
  • Put your transmitter module into bind mode via the ExpressLRS Configurator or transmitter menu.
  • Wait for the receiver LED to indicate a successful bind (usually a solid light).
  • Test the range and response by moving sticks on your transmitter and observing servo movement.

Step 4: Final Setup and Testing

Once bound, it’s time to check everything:

  • Verify all control surfaces move correctly and in the right direction.
  • Adjust servo reversing or endpoints in your flight controller or transmitter if needed.
  • Perform a range check outdoors to confirm signal strength and reliability.
  • Secure all wiring and receiver inside your airframe, avoiding interference with moving parts.

Tips for UK Pilots

In the UK, make sure to:

  • Fly within the legal line-of-sight range and height limits.
  • Use frequency bands allowed for RC use (ELRS typically operates on 2.4GHz).
  • Keep firmware updated to benefit from the latest features and fixes.

Conclusion

Setting up ExpressLRS with PWM outputs on your fixed wing is a great way to enhance your flying experience. With careful firmware flashing, proper wiring, and thorough testing, you’ll enjoy a reliable, low-latency control link that can outperform many traditional RC systems. Happy flying!

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