Radiomaster ER4 2.4Ghz 4CH 10mw ExpressLRS PWM Receiver Instruction Manual

1. Introduction

The Radiomaster ER series of PWM receivers are built upon the innovative ExpressLRS system, offering a blend of high performance, reliability, and flexible configuration. This system provides fast response speeds and an ultra-long range, enhancing your remote control experience.

The ER4 PWM receiver is specifically designed to control up to 4 servos simultaneously. Its compact and lightweight design makes it ideal for small aircraft models, ship models, car models, and other applications where space and weight are critical, while still delivering full-range capabilities.

2. Features

• Based on the Revolutionary ExpressLRS System
• High performance, high reliability, flexible configuration, fast response speed, and ultra-long range
• Supports 4 PWM Channels
• Optimized ground-up PCB design for superior reliability and stability
• Automatically detects and telemeters external battery voltage or built-in receiver voltage
• Supports Wi-Fi updates and WEBUI configuration for easy firmware management
• High quality 2.54 mm connector for secure connections
• Standard 15 cm High Sensitivity Antenna for extended range
• Suitable for small aircraft, boats, cars, and other models

3. Specifications

4. Package Contents

The following items are included in your Radiomaster ER4 receiver package:

• 1 x ER4 2.4GHz ELRS PWM Receiver
• 2 x Heat-shrink tube
• 1 x Voltage telemetry wire (Type-A)
• 1 x User Card

5. Setup & Installation

5.1 Physical Installation

The ER4 receiver is designed for compact installations. Ensure it is mounted securely in your model, away from potential interference sources like motors, ESCs, and large metal objects. The antenna should be positioned to maximize signal reception, typically perpendicular to the main body of the model and away from carbon fiber structures.

5.2 Wiring Connections

The ER4 features 4 PWM output channels and dedicated power input pins. Connect your servos to channels 1-4. Ensure correct polarity when connecting power (DC 4.5 - 8.4V) to the receiver. The optimized PCB design ensures consistent MCU voltage for reliable servo operation.

5.3 Antenna Placement

The ER4 comes with a 15cm high sensitivity antenna. Proper antenna placement is crucial for maintaining a strong and stable radio link. Avoid bending the antenna sharply or placing it near conductive materials that could shield the signal.

6. Binding and Operation

6.1 Binding Procedure

The Radiomaster ER4 receiver uses the ExpressLRS protocol. To bind the receiver to your transmitter, follow the standard ExpressLRS binding procedure:

1. Power on the receiver. The LED will flash slowly.
2. Power off the receiver.
3. Repeat steps 1 and 2 two more times.
4. On the fourth power-up, the receiver LED should flash rapidly, indicating it is in binding mode.
5. On your ExpressLRS compatible transmitter, navigate to the ELRS LUA script or menu and select 'Bind'.
6. Once bound, the receiver LED will turn solid, indicating a successful connection.

6.2 Voltage Telemetry

The ER4 supports automatic voltage telemetry. It can report the built-in receiver voltage or an external battery voltage if connected to the EXT-V port. The battery voltage detection range is DC 4.0-35V. This feature allows you to monitor your model's power status directly from your transmitter.

7. Firmware Updates & Configuration

The ER4 receiver supports convenient Wi-Fi updates and WEBUI configuration. This allows you to easily update the firmware and adjust settings without needing to physically connect the receiver to a computer via USB.

7.1 Wi-Fi Update Procedure

1. Power on the receiver.
2. After a short period, the receiver will enter Wi-Fi mode (if not already bound or if binding fails).
3. Connect to the receiver's Wi-Fi network from your computer or smartphone (SSID typically 'ExpressLRS RX' with password 'expresslrs').
4. Open a web browser and navigate to 10.0.0.1 (or the IP address displayed by the receiver).
5. From the WEBUI, you can upload new firmware files or configure various ExpressLRS settings.
6. After updating or configuring, restart the receiver.

8. Maintenance

The Radiomaster ER4 receiver is a robust electronic component. Minimal maintenance is required:

• Keep the receiver clean and free from dust, dirt, and moisture.
• Inspect all wiring connections periodically for signs of wear or damage.
• Ensure the antenna is securely attached and not damaged.
• Avoid exposing the receiver to extreme temperatures or direct sunlight for prolonged periods.
• If using heat-shrink tubing, ensure it is properly applied to protect the board.

9. Troubleshooting

If you encounter issues with your ER4 receiver, consider the following:

• No Link/Binding Issues: Double-check your binding procedure. Ensure your transmitter's ExpressLRS module is powered on and operating on the correct frequency. Verify that the receiver's LED is flashing rapidly when attempting to bind.
• Intermittent Signal Loss: Check antenna placement and condition. Ensure there are no obstructions or sources of interference near the receiver or antenna. Verify the power supply to the receiver is stable and within the specified voltage range.
• Servo Glitches/Unresponsive Servos: Confirm that servos are correctly plugged into the PWM channels with the correct polarity. Check the power supply to the servos and receiver. Ensure the PCB is not damaged.
• Telemetry Not Working: Verify the external voltage telemetry wire (Type-A) is correctly connected if you are monitoring an external battery. Check your transmitter's telemetry settings.
• Unable to Access Wi-Fi WEBUI: Ensure the receiver is in Wi-Fi mode (LED flashing rapidly). Confirm you are connected to the correct Wi-Fi network and using the correct IP address (usually 10.0.0.1).

For further assistance, refer to the official ExpressLRS documentation or contact Radiomaster support.

10. User Tips

• Optimal Antenna Placement: For best range and signal quality, ensure the receiver antenna is mounted as far as possible from carbon fiber, metal, and other electronic components. Orient the antenna vertically or horizontally, depending on your model's flight orientation, to maintain consistent signal.
• Power Supply Stability: While the ER4 has an optimized PCB for stable MCU voltage, ensuring a clean and stable power supply (within 4.5-8.4V) from your BEC or flight controller is crucial for overall system reliability, especially when driving multiple servos.
• Firmware Management: Regularly check the official ExpressLRS and Radiomaster websites for the latest firmware updates. These updates often include performance improvements, bug fixes, and new features. The Wi-Fi update feature makes this process very convenient.
• Pre-flight Checks: Always perform a range check and verify all control surfaces and telemetry data before each flight or operation to ensure everything is functioning correctly.

11. Support

For technical support, warranty information, or additional resources, please visit the official Radiomaster website or contact their customer service. Ensure you have your product model and any relevant purchase information ready when seeking support.