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

on

Introduction to ExpressLRS and PWM Outputs

If you're a hobby RC pilot or maker in the UK looking to upgrade your fixed-wing aircraft control system, ExpressLRS (ELRS) is a fantastic choice. It offers long-range, low-latency radio control using open-source technology. While many ELRS setups use serial protocols like CRSF, some fixed wings still rely on traditional PWM outputs to control servos. This guide will help you set up ExpressLRS with PWM outputs, ensuring compatibility with your existing servos and ESCs.

What You Need

Before starting, make sure you have the following components:

  • An ExpressLRS compatible receiver with PWM output pins (e.g., some ELRS RX modules or boards with PWM ports)
  • A fixed-wing aircraft with standard servos and ESCs that accept PWM signals
  • A compatible transmitter with ExpressLRS module or built-in ELRS support
  • A computer for flashing your receiver with the ELRS Configurator software
  • Basic tools: soldering iron (if needed), connectors, and wiring

Step 1: Flash the ExpressLRS Receiver

Start by downloading the latest ELRS Configurator from the official ExpressLRS website. Connect your receiver to your PC using a USB-to-serial adapter or built-in USB port if available. Follow these steps:

  • Open ELRS Configurator and select your receiver model.
  • Choose the correct firmware version (make sure PWM output support is enabled if applicable).
  • Set the desired RF parameters (frequency, power, etc.) based on your flying environment.
  • Flash the firmware and confirm the process completes successfully.

Step 2: Wiring the Receiver to Your Servos

Once the receiver is flashed, you’ll need to connect the PWM outputs to your servos and ESC. Typically, ELRS receivers with PWM outputs have individual channels exposed as separate pins:

  • Identify each PWM output pin on the receiver (e.g., CH1, CH2, CH3, CH4).
  • Use servo extension cables or solder wires to connect these pins to your servos’ signal inputs.
  • Ensure the ground and power (usually 5V) lines are connected properly between the receiver and servos/ESC.

Double-check the polarity to avoid damage to your components.

Step 3: Binding the Receiver and Transmitter

Power on your receiver while holding the bind button (or follow your receiver’s specific binding instructions). Then, activate the binding mode on your ExpressLRS transmitter module or radio. Wait for the LEDs to indicate a successful bind (usually a steady green light). After binding, power cycle the receiver and transmitter to confirm communication.

Step 4: Testing and Calibration

With everything wired and bound, test each servo channel by moving sticks and switches on your transmitter. Verify that each control surface responds correctly and smoothly.

Adjust endpoints and trims in your transmitter if needed to ensure neutral positions and full control throws. This step is crucial for safe flying.

Tips for a Smooth Setup

  • Use high-quality, shielded servo cables to reduce interference.
  • Secure all wiring to prevent vibrations or disconnections during flight.
  • Keep your receiver antenna clear of metal parts and carbon fibre to maintain good signal quality.
  • Always perform a range check before flying to ensure reliable communication.

Conclusion

Setting up ExpressLRS on a fixed wing with PWM outputs is straightforward once you have the right hardware and follow the steps carefully. This setup combines the modern, robust ELRS radio link with the familiar PWM servo controls, making it perfect for pilots upgrading older models or those who prefer traditional servo interfaces. Happy flying and tinkering!

Comments

Post a Comment