RadioMaster XR3 Receiver User Manual

Product Overview

This document provides instructions for the RadioMaster XR3 Nano Multi-Frequency Antenna Diversity ExpressLRS Receiver. It details the product's specifications, configuration settings, and binding procedures.

The XR3 receiver is depicted from its top and bottom views. The top view shows two U.FL antenna connectors, labeled 'U.FL', positioned at the top edge. Various electronic components and integrated circuits are visible on the board. The bottom view highlights the main chips, identified as 'ESP32-C3' and 'LR1121', along with pin labels 'RX', 'TX', '5V', 'GND' on one side, and 'TX2', 'RX2' on another. The overall dimensions are indicated as 15mm across the top and 22mm in length, with a weight of 1.3 grams.

Antennas are connected via two U.FL connectors. The product includes two T-shaped antennas, which can be either 2.4GHz, 900MHz, or dual-band depending on the selected package.

Specifications

• Item: XR3 Nano Multi-Frequency Antenna Diversity ExpressLRS Receiver
• Type: ISM2.4, FCC915
• MCU: ESP32C3
• RF Chip: LR1121
• RF Connector: 2x IPEX-1
• Antenna: 2x T-Antenna (2.4GHz, 900MHz, or Dual-band depending on package)
• Frequency Range: 2.4GHz / Sub-G 900MHz [ISM 2.4GHz / FCC915]
• Maximum Receive Refresh Rate: DK500Hz / K1000Hz
• Minimum Receiver Refresh Rate: 25Hz
• Working Voltage: DC 5.0 - 12.6V
• Weight: 1.3g (without antenna)
• Dimension: 22mm * 15mm * 4mm
• Firmware Version: ExpressLRS v3.5.1 pre-installed
• Bus Interface 1: CRSF
• Bus Interface 2: UART

Includes

• 1 x XR3 Nano Multi-Frequency Antenna Diversity ExpressLRS Receiver
• 2 x T Antenna (2.4GHz, 900MHz, or Dual-band depending on package)
• 1 x CRSF Wire
• 3 x Heat-Shrinkable Tube
• 1 x Manual Card

Default Firmware

The default firmware is RadioMaster XR3 2.4/900 Diversity RX. For more information, please visit the ELRS website: https://www.expresslrs.org/2.0/

Configuration

To configure the receiver, follow these steps using Betaflight Configurator:

1. Open Betaflight Configurator.
2. Navigate to the Ports tab.
3. Enable the corresponding UART as a Serial RX (e.g., UART2 as shown in the diagram). Save and restart the configurator.

In the Configuration tab:

• Ensure the UART for the receiver is set to 'Serial Rx' (in the Ports tab).
• Select the correct data format from the drop-down menu, which should be CRSF.
• On the Configuration tab, click on 'Serial-based receiver' in the Receiver panel and select CRSF.

Traditional Binding

Ensure the Binding Phrase field is uncommented in the Device options on the RX.

1. Power OFF your transmitter/radio.
2. Plug in and unplug your receiver three times.
3. Verify the LED is performing a quick double blink, indicating the receiver is in bind mode.
4. Power ON your transmitter/radio and use the [BIND] button on the ExpressLRS Lua script to send a binding pulse.
5. A solid light on the receiver indicates successful binding.