RadioMaster XR1 Receiver User Manual

Product Overview

This document provides user information for the RadioMaster XR1 Nano Multi-Frequency ExpressLRS Receiver. The XR1 receiver supports both 2.4GHz and 900MHz frequency bands, utilizing the ESP32C3 MCU and Semtech LR1121 RF chip.

Diagram Description

The XR1 Receiver User Manual features a prominent diagram illustrating the physical layout and connectivity of the XR1 receiver. This diagram is divided into two main views: 'TOP' and 'BOTTOM'.

Top View: This perspective shows the receiver board with its compact form factor. Key components and connectors are clearly labeled. A U.FL connector is visible, typically used for attaching an external antenna. The main integrated circuits are identified as the ESP32C3 MCU and the Semtech SX1276 chip (labeled as 2419 480309 1). A small LED indicator and a BIND button are also present. The pinouts are clearly marked with labels: RX, TX, 5V, and G (Ground). The diagram indicates the 900 MHz frequency capability and the 2.4 GHz frequency capability, with dimensions suggesting the board is approximately 20mm in length.

Bottom View: This view complements the top perspective, showing the underside of the board. It also highlights the BIND button and pinouts (5V, TX, RX, G). The diagram indicates the 2.4 GHz frequency band and provides overall dimensions for the receiver, showing a length of 13.3mm and a width of 11.5mm, with a total height of 15mm.

The manual also includes a visual representation of the Betaflight Configurator interface, showing the 'Ports' tab and the 'Configuration' tab with specific settings for enabling Serial RX and selecting CRSF as the receiver protocol.

Specifications

• Type: ISM2.4 or FCC915
• MCU: ESP32C3
• RF chip: Semtech LR1121
• RF connector: IPEX-1
• Antenna: 1x T-Antenna (options for 2.4GHz, 900MHz, or Dual-band depending on package)
• Frequency Range: 2.4GHz or Sub-G 900MHz
• Telemetry Power: 100mW
• Maximum Packet rate: DK500Hz / K1000Hz
• Minimum Packet refresh rate: 50Hz
• Working voltage: 5V
• Weight: 1.0g (without antenna)
• Dimension: 20mm * 13mm * 3mm
• Bus interface 1: CRSF
• Bus interface 2: UART
• Firmware Version: ExpressLRS v3.5.1 (pre-installed)

Includes

• 1 * XR1 Nano Multi-Frequency ExpressLRS Receiver
• 1 * T Antenna (2.4GHz, 900MHz, or Dual-band, depending on selected package)
• 1 * CRSF wire
• 3 * Heat-Shrinkable Tube
• 1 * Manual Card

Default Firmware

The default firmware is RadioMaster XR1 2.4/900 RX.

For more information, visit the ELRS website: https://www.expresslrs.org/2.0/

Configuration

This section outlines how to configure the receiver, typically within flight controller software like Betaflight.

Configuration Steps:

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).
4. Save and restart the configurator.
5. In the 'Configuration' tab, under the 'Receiver' panel, select 'Serial-based receiver' and choose 'CRSF' as the provider.

Traditional Binding

Follow these steps to bind the receiver to your transmitter:

1. Ensure the 'Binding Phrase' field is uncommented in the Device options on the RX.
2. Power OFF your transmitter/radio.
3. Plug in and unplug your receiver three times. The LED should blink rapidly (double blink) indicating bind mode.
4. Power ON your transmitter/radio.
5. Use the [BIND] button within the ExpressLRS Lua script on your transmitter to send a binding pulse.
6. A solid LED light on the receiver indicates a successful bind.