RadioMaster RP4TD ExpressLRS 2.4GHz Diversity Receiver User Manual

Introduction

This manual provides essential instructions for the proper installation, operation, and maintenance of your RadioMaster RP4TD ExpressLRS 2.4GHz Diversity Receiver. Please read this manual thoroughly before use to ensure optimal performance and safety.

Safety Information

Warning: This product is not intended for use by children.

Always ensure proper ventilation when operating the receiver.

Avoid exposing the receiver to moisture, extreme temperatures, or direct sunlight.

Disconnect power before performing any maintenance or installation procedures.

Package Contents

Verify that all items listed below are included in your package:

• 1 x RP4TD ExpressLRS 2.4GHz Diversity Receiver
• 1 x CRSF Wire
• 3 x Heat-Shrinkable Tube
• 2 x 65mm 2.4GHz T Antenna (Pre-installed)
• 1 x User Manual (This document)

Image: The RadioMaster RP4TD receiver with its two T-antennas, a CRSF wire, and three heat-shrinkable tubes.

Product Overview

The RadioMaster RP4TD is an advanced ExpressLRS 2.4GHz Diversity Receiver designed for reliable and high-performance radio control applications. It features dual RF chips and antennas for enhanced signal reception and stability.

Key Features

• Gemini mode compatible for advanced signal processing.
• Reliable DCDC power supply circuit for stable operation.
• Class-leading Signal-to-Noise Ratio (SNR) and Received Signal Strength Indicator (RSSI) performance.
• Optimized PCB design for efficient heat dissipation.
• Upgraded antennas for improved durability and signal performance.
• UART pads for extended application connectivity.
• Dual Temperature Compensated Crystal Oscillators (TCXO) for frequency stability.
• 2x 100mW RF Telemetry power output.
• Compatible with all 2.4GHz ExpressLRS modules and transmitters.
• Built-in WiFi for wireless firmware upgrades and configuration via WebUI.

Image: A detailed view of the RP4TD receiver's circuit board, highlighting the ESP32 MCU and SX1281 RF chips.

Specifications

Setup

1. Wiring

Connect the RP4TD receiver to your flight controller or device using the provided CRSF wire. Ensure correct polarity and pin assignments for VCC, GND, TX, and RX. Refer to your flight controller's manual for specific wiring diagrams.

Typical CRSF Wiring:

• VCC: Connect to 4.5-12.0V power supply.
• GND: Connect to ground.
• TX: Connect to RX pad on flight controller (e.g., UART RX).
• RX: Connect to TX pad on flight controller (e.g., UART TX).

2. Binding

The RP4TD receiver comes pre-installed with ExpressLRS V3.3.0 firmware. To bind the receiver to your ExpressLRS transmitter module:

1. Power on the receiver. The LED on the receiver will flash slowly.
2. Power off the receiver, then power it on again. Repeat this process three times.
3. On the third power-up, the LED will begin to flash rapidly, indicating it is in binding mode.
4. On your ExpressLRS transmitter, initiate the binding process. Refer to your transmitter's manual for specific instructions on how to enter binding mode.
5. Once bound, the LED on the receiver will turn solid, indicating a successful connection.

Note:

Ensure your transmitter's ExpressLRS firmware version is compatible with the receiver's firmware (V3.3.0 or compatible version).

3. Firmware Update (Optional)

The RP4TD features built-in WiFi for convenient wireless firmware updates.

1. Power on the receiver.
2. If the receiver is not bound to a transmitter, it will automatically enter WiFi hotspot mode after a short period. If it is bound, you may need to power cycle it rapidly three times to force it into WiFi mode (similar to binding).
3. Connect your computer or mobile phone to the WiFi network broadcast by the receiver (SSID typically "ExpressLRS RX" or similar).
4. Open a web browser and navigate to http://10.0.0.1 (or http://elrs_rx.local).
5. Follow the on-screen instructions in the WebUI to flash new firmware.

Alternatively, firmware can be updated via the UART interface using the ExpressLRS Configurator.

Operating Instructions

Powering On

Connect the receiver to a power source within the specified voltage range (DC 4.5-12.0V). The LED will indicate its status.

LED Status Indicators

• Slow Flash: Not bound, searching for transmitter.
• Rapid Flash: Binding mode.
• Solid On: Successfully bound and receiving telemetry.
• Double Flash: WiFi mode active.

Telemetry

The RP4TD provides telemetry feedback to your compatible ExpressLRS transmitter. Ensure telemetry is enabled and configured correctly on your transmitter and flight controller for full functionality.

Gemini Mode

The RP4TD supports Gemini mode, which utilizes both RF chips for enhanced signal diversity. Ensure your ExpressLRS transmitter and firmware support Gemini mode for optimal performance.

Maintenance

Cleaning

Gently clean the receiver with a dry, soft cloth. Avoid using liquids or solvents that could damage the electronic components.

Antenna Care

Ensure the antennas are securely connected and positioned correctly for optimal signal reception. Avoid bending or damaging the antenna elements.

The included heat-shrinkable tubes can be used to protect antenna connections and wires.

Firmware Updates

Periodically check the official ExpressLRS website or RadioMaster support channels for new firmware releases. Updating firmware can provide performance improvements, new features, and bug fixes.

Troubleshooting

Receiver Not Binding

• Ensure the receiver is powered correctly (4.5-12.0V).
• Confirm the receiver is in binding mode (rapidly flashing LED).
• Verify your transmitter is in binding mode and broadcasting ExpressLRS.
• Check for firmware compatibility between the receiver and transmitter.
• Try moving the transmitter closer to the receiver during the binding process.

No Telemetry

• Confirm the receiver is successfully bound (solid LED).
• Check wiring between the receiver and flight controller (TX/RX connections).
• Ensure telemetry is enabled and configured correctly in your flight controller's firmware (e.g., Betaflight, ArduPilot).
• Verify your transmitter is configured to receive telemetry.

Poor Signal Quality / Range

• Check antenna placement and orientation. Ensure they are not obstructed by carbon fiber or other conductive materials.
• Verify antenna connections are secure.
• Ensure there are no sources of interference near the receiver or antennas.
• Confirm the transmitter's RF power is set appropriately.
• Consider updating firmware on both receiver and transmitter.

Warranty and Support

For warranty information and technical support, please refer to the official Helidirect or RadioMaster website. Keep your proof of purchase for warranty claims.

Online resources for ExpressLRS firmware and configuration can be found at the official ExpressLRS project website.

For further assistance, contact Helidirect customer support.