1. Introduction
The DX-LR20 is a programmable, low-power, ultra-long-distance LoRa pure RF module designed for intelligent wireless data transmission. It is available as a standalone module (DX-LR20-433M22S, DX-LR20-900M22S) or integrated into a development board (DX-LR20-433M22SP, DX-LR20-900M22SP) featuring an STM32F103C8T6 microcontroller. These modules support 430-470MHz and 850-960MHz global Sub-GHz frequency bands, offering reliable communication up to 8KM in open visibility.
Video: DX-LR20 LoRa Module Overview and Features
2. Product Highlights
- Original Semtech LLCC68 Chip for secure and reliable communication.
- Supports LoRa® and (G)FSK modulation.
- Maximum transmit power up to +22dBm.
- Receiver sensitivity as low as -148dBm (LoRa® mode).
- Ultra-low power consumption: Receive current 4.6mA, sleep current as low as 0.7µA.
- Long-range communication up to 8KM in open visibility.
- Integrated STM32F103C8T6 microcontroller on development boards for easy prototyping.
- Multiple antenna interface options: stamp hole, round hole, and detachable RF connectors (e.g., U.FL).
- Industrial-grade quality: Dustproof, ESD protected, EMI resistant, operating temperature -40°C to +85°C.
Image: Key features of the Semtech LLCC68 chip.
Image: LR20-433M22SP Key Features and module dimensions.
Image: Performance comparison between LLCC68 and SX1278/SX1276 chips.
3. Setup
3.1 Package Contents
A typical developer package includes:
- DX-LR20 LoRa Module (e.g., LR20-433M22S or LR20-900M22S)
- DX-LR20 Development Board (e.g., LR20-433M22SP or LR20-900M22SP)
- USB Type-C Cable
- Antenna(s)
Image: DX-LR20 Development Board Kit showing modules, USB cables, and antennas.
3.2 Module vs. Development Board
The DX-LR20 module (e.g., LR20-433M22S) requires soldering for integration into custom circuits. The DX-LR20 development board (e.g., LR20-433M22SP) is designed for direct use, offering a plug-and-play experience for quick verification and development.
3.3 Development Board Components
Image: Labeled diagram of the DX-LR20 Development Board.
- Bottom board pins
- Base antenna connector
- Module antenna connector
- Module
- Power indicator
- User-customizable function
- Reset button
- Key button
- Type-C powered, UART download port
- ONBOARD MAIN CONTROL STM32F103
3.4 Pin Definitions
SMD Module Pin Definitions:
| Pin number | Pin name | Pin function | Description |
|---|---|---|---|
| 1,2,3,4,10,11,12,20,22 | GND | Power Ground | - |
| 5 | DIO3 | Multi functional digital input/output - external TCXO power supply voltage | input/output |
| 6 | RX | Antenna switch | Used to switch between receiving and transmitting |
| 7 | TX | Antenna switch | Used to switch between receiving and transmitting |
| 8 | DIO2 | Multi purpose digital input/output | input/output |
| 9 | VCC | Power input pin | 3.3V (typical value) |
| 13 | DIO1 | Multi purpose digital input/output | input/output |
| 14 | BUSY | Used for status indication | - |
| 15 | RESET | Reset foot | - |
| 16 | MISO | SPI data output pin | - |
| 17 | MOSI | SPI data input pin | - |
| 18 | SCK | SPI clock input pin | - |
| 19 | NSS | Module chip selection pin, used to start an SPI communication | - |
| 21 | ANT | Radio Frequency Interface | - |
Development Board Pin Definitions:
| Pin number | Pin name | Pin function | Description |
|---|---|---|---|
| 1,19,20,22 | 3.3V | 3.3V power supply | - |
| 2,3,4,6,7,8,13,14,15,16,24,25,26,27,28,31,32,33,34,35,36,37,38,39,40 | PC13,PC14,PC15,PA0,PA1,PA2,PA3,PA8,PB1,PB10,PB11,PB12,PB13,PB14,PB15,PA11,PA12,PA15,PB3,PB4,PB5,PB6,PB7,PB8,PB9 | IO | User defined |
| 9 | NSS | Module CE pin for SPI communication initiation. | - |
| 10 | SCK | SPI clock input pin | - |
| 11 | MISO | SPI data output pin | - |
| 12 | MOSI | SPI data input pin | - |
| 17 | RST | Reset | - |
| 18,23 | GND | Power Ground | - |
| 29 | 5V | 5V power supply | - |
| 30 | PA9 | TX | Send Data |
| 30 | PA10 | RX | Receive Data |
Image: Detailed pinout diagram for the DX-LR20 Development Board.
3.5 Antenna Connection
It is crucial to connect the antenna before powering on the module or development board to prevent damage from unloaded operation. The modules support both on-board stamp hole antennas (default, suitable for most applications) and U.FL antenna connectors for external antennas, which are ideal for extended range and complex environments.
Image: Illustration of U.FL and Stamp Hole antenna options.
4. Operating Instructions
4.1 Communication Modes
The DX-LR20 modules support various communication modes:
- Transparent Transmission: Requires the sender and receiver to be on the same channel to send data.
- Fixed-Point Transmission: Communicate with modules using specified addresses and channels. Data transmission format is hexadecimal: receiving address + receiving channel + data.
- Broadcast Transmission: Communicate with designated channel modules. Data transmission format is hexadecimal: receiver channel + data.
Image: Diagrams illustrating transparent, fixed-point, and broadcast communication modes.
4.2 LoRa Spread Spectrum Technology
The DX-LR20 utilizes LoRa spread spectrum technology for ultra-stable, long-range communication, significantly surpassing traditional single-frequency methods in anti-interference capabilities and stability.
Image: Explanation of LoRa Spread Spectrum Technology and global license-free ISM bands.
4.3 Frequency Bands
Our LoRa solutions are globally applicable across multiple countries, supporting license-free ISM bands. Please verify local RF spectrum regulations prior to operation.
| Area | Frequency Band | Center Frequency |
|---|---|---|
| North America | 902-928MHz | 915MHz |
| South America | 915-928MHz | 915MHz / 928MHz |
| Europe | 866-915/433MHz | 433MHz / 868MHz / 915MHz |
| Oceania | 915-928MHz | 915MHz / 928MHz |
| Asia Pacific | 915-923MHz | 920MHz |
| South Asia | 865-867MHz | 866MHz |
| Southeast Asia | 920-925MHz | 923MHz |
4.4 Technical Documentation
Professional technical documentation is available to help you use the module more easily and conveniently. This includes:
- Development Environment IDE
- Chip Technical Manual
- Module Technical Manual
- Development Board Technical Manual
- Testing Tools
- Hardware Documentation
- Code Examples
- Reference Links
For DX-LR20-433M22S documentation, visit: DX-LR20-433M22S Documentation
For DX-LR20-900M22S documentation, visit: DX-LR20-900M22S Documentation
5. Maintenance
The DX-LR20 modules are designed for industrial-grade quality, featuring dustproof, ESD protection, and EMI resistance. To ensure optimal performance and longevity:
- Operate within the specified temperature range of -40°C to +85°C.
- Avoid exposing the module to excessive dust or moisture.
- Handle with care to prevent electrostatic discharge (ESD) damage.
- Ensure proper antenna connection before powering on.
6. Troubleshooting
If you encounter issues, please refer to the comprehensive technical documentation provided via the download links in Section 4.4. The documentation includes detailed guides, code examples, and troubleshooting tips that can help resolve common problems.
6.1 Common Issues & Solutions
- No communication: Verify antenna connection, power supply, and correct pin wiring. Check communication protocol settings (e.g., SPI).
- Limited range: Ensure line-of-sight, proper antenna placement, and correct frequency band for your region.
- Module not powering on: Check Type-C cable connection and power source.
7. Specifications
7.1 General Specifications (LR20 Module & Development Board)
| Parameter | Details |
|---|---|
| Chip Model | Semtech LLCC68 Chip (Module), STM32F103C8T6 Chip (Development Board) |
| Module Size | 20mm × 14mm × 2.3mm (Module), 70mm × 30mm × 20mm (Development Board) |
| Communication Protocol | LoRa protocol |
| Transmission Power | 0 ~ +22dBm |
| Frequency Band | 430-470MHz (for 433Mhz variants), 850-930MHz (for 900Mhz variants) |
| Modulation Methods | LoRa and GFSK |
| Working Voltage | 1.8V-3.7V (Module), 5V (Development Board) |
| Receiver Sensitivity | -138dBm (LoRa mode) / -124dBm |
| RF Input Impedance | 50 Ω |
| Transmission Distance | Open transmission distance of 8km |
| FIFO | 256Byte |
| Hardware Interface | SPI |
| Working Temperature | -40°C ~ +85°C |
| Crystal Oscillator Frequency | 32MHz |
Image: Detailed specifications table for LR20 modules and development boards.
8. User Tips
- Meshtastic Compatibility: Users have inquired about flashing the module with Meshtastic firmware. While the module supports custom programming, compatibility with specific third-party firmware like Meshtastic may require additional development or specific configurations. Refer to the technical documentation and community resources for guidance.
- Initial Development: For first-time users, purchasing a developer package (e.g., LR20-433M22SP Kit) is recommended as it includes a development board, USB cable, and antennas, allowing for quick product verification and prototyping without needing to solder the module directly.
9. Support
For any further questions, technical support, or if you are unable to download the provided documentation, please contact our after-sales team:
Email: Manager@szdx-smart.com
We aim to respond to your inquiries within 24 hours.
