ELRS Quick Start Guide
I. What is ExpressLRS (ELRS)
ExpressLRS (abbreviated as ELRS) is an open-source, high-performance remote control protocol designed specifically for FPV and fixed-wing aircraft. Developed based on LoRa technology, it achieves long-range transmission while maintaining ultra-low latency, making it one of the most popular remote control protocols in the RC aviation field.
1.1 Core Features
- Ultra-low latency: Rapid control response for a more responsive flying experience
- Long-range transmission: Maintains stable connection over several kilometers
- High refresh rate: Supports multiple rate options from 25Hz to 1000Hz
- Open-source and free: Active global community with continuous optimization and updates
1.2 Applicable Scenarios
| Scenario | Description |
|---|---|
| Fixed-wing | Long-range gliding, aerial surveying, line patrol missions |
| FPV racing drones | High-speed flight, precise control |
| Multirotors | Aerial photography, inspection, light-duty operations |
II. ELRS Core Advantages
Compared to traditional remote control protocols, ELRS offers the following significant advantages:
| Advantage | Description |
|---|---|
| Ultra-low latency | Control signal delay as low as 5ms for faster aircraft response |
| Long-range transmission | Can achieve control distances of several kilometers under ideal conditions |
| High refresh rate | Supports multiple data packet rates to suit different flight needs |
| Bidirectional communication | Supports telemetry data feedback for real-time aircraft status monitoring |
| Strong anti-interference capability | Based on LoRa frequency hopping technology, remains stable in complex environments |
| Open-source ecosystem | Free to use with continuous iteration and optimization by the community |
III. ELRS Working Mode Comparison
ELRS primarily supports two working modes: CRSF and MAVLink:
3.1 Mode Comparison Table
| Comparison Item | CRSF Mode | MAVLink Mode |
|---|---|---|
| Core Purpose | Standard remote control control | Remote control + Telemetry + Ground control station |
| Transmission Content | Control signals + Basic telemetry | Control signals + Complete MAVLink data |
| Communication Direction | Bidirectional (limited telemetry data) | Bidirectional (complete telemetry data) |
| Setup Difficulty | Simple | Moderate |
| Recommended Scenarios | Daily flying, sport flying, training | Long-range, aerial surveying, mission planning |
3.2 How to Choose a Mode?
Mode Selection Recommendation
CRSF Mode: If you simply want your aircraft to stably receive remote control commands for daily flying and training, choose CRSF mode for simpler setup
MAVLink Mode: If you need ground station telemetry, mission planning, or real-time aircraft status monitoring (GPS, battery level, attitude, etc.), choose MAVLink mode
IV. CoreWing ELRS Product Ecosystem
CoreWing provides a complete ELRS solution:
4.1 Transmitter Devices
Sirius 2.4G ELRS Transmitter Module
- Supports both ELRS CRSF and ELRS MAVLink dual modes
- Built-in Backpack function supporting BLE/Wi-Fi telemetry output
- One-click firmware upgrade via CoreWing APP
4.2 Receiver Devices
SkyGuy Nano 2G4 RX Receiver
- Ultra-compact size, lightweight design
- Supports CRSF and MAVLink protocol switching
- RGB status indicator for clear connection status visualization
4.3 Flight Controller Compatibility
CoreWing F405 WING V2
- Serial port 6 DMA support, perfect for ELRS MAVLink mode
- Supports high baud rate communication up to 460800bps
- One-click receiver parameter configuration via CoreWing APP
V. Quick Start Guide
5.1 Hardware Preparation List
| Device | Recommended Model | Description |
|---|---|---|
| RC Transmitter | RadioMaster TX16S | Any transmitter supporting CRSF protocol |
| Transmitter Module | Sirius 2.4G ELRS | CoreWing custom transmitter module |
| Receiver | SkyGuy Nano 2G4 RX | Compact receiver |
| Flight Controller | CoreWing F405 WING V2 | Supports ELRS MAVLink |
5.2 Four-Step Getting Started
Step 1: Enable Transmitter Module
Enter transmitter model settings → SETUP page → Enable External RF Mode → Set Mode to CRSF, Baudrate to 1.87M
Important
It is recommended to set the baud rate to 1.87M, otherwise you may not be able to enter the ELRS Lua script or set F1000 rate.
Step 2: Bind Transmitter Module and Receiver
- Method 1: Triple power-on binding (power on the receiver three times consecutively to enter binding mode)
- Method 2: WiFi configuration binding (connect to receiver WiFi with a computer to modify password)
Step 3: Firmware Upgrade
Use the "Sirius Upgrade" function in the CoreWing APP toolbar to upgrade the transmitter module, receiver, and Backpack firmware with one click.
Step 4: Mode Configuration
Select CRSF or MAVLink mode according to your needs and configure accordingly in the ELRS Lua script.
5.3 Receiver Connection Notes
Warning
CoreWing Flight Controller Receiver Connection:
- Must be connected to serial port 6 (UART6)
- Reason: Serial port 6 has built-in DMA support, enabling stable operation at high baud rates of 460800bps
⚠️ Note: Other serial ports (such as serial port 4) may be hardware compatible but lack DMA support, which will prevent MAVLink communication from working properly.
VI. Firmware Switching Guide
The CoreWing Sirius transmitter module supports both ELRS and mLRS firmware, allowing flexible switching according to needs:
| Switching Requirement | Tutorial Link |
|---|---|
| Continue using ELRS, upgrade firmware | Sirius Transmitter Module and SkyGuy Upgrade ELRS Firmware |
| ELRS CRSF ↔ ELRS MAVLink | Sirius Transmitter Module and SkyGuy Upgrade ELRS Firmware |
| ELRS → mLRS | Sirius Transmitter Module Firmware Switching Guide: ELRS → mLRS |
Baud Rate Setting Reminder
- ELRS uses
5.25Mbaud rate - mLRS uses
400kbaud rate
Be sure to modify the transmitter baud rate after switching firmware!
VII. Recommended Learning Path
Choose the appropriate learning path based on your usage needs:
7.1 Beginner Learning Path
- Understand ELRS basics (this article)
- Complete transmitter module and receiver binding
- Configure CRSF mode to start daily flying
- Learn to use ELRS Lua script to adjust parameters
7.2 Advanced Learning Path
- Master basic CRSF mode operations
- Learn MAVLink mode configuration
- Connect to CoreWing APP via Backpack
- Use ground control station for mission planning
7.3 Related Tutorials
| Tutorial | Link |
|---|---|
| ELRS Binding Tutorial | View |
| ELRS Firmware Upgrade Tutorial | View |
| ELRS MAVLink Mode Configuration | View |
| Sirius Transmitter Module APP Connection | View |
VIII. Common Questions (Q&A)
Q1: What is the difference between ELRS and traditional RC systems?
A: Compared to traditional FM/DSM protocols, ELRS offers the following advantages:
- Lower latency: Starting from 5ms, while traditional protocols typically exceed 20ms
- Longer range: Greater transmission distance at the same power
- Stronger anti-interference: LoRa frequency hopping technology maintains stability in complex environments
- Richer features: Supports full telemetry, parameter configuration, etc.
Q2: How to choose between CRSF or MAVLink mode?
A:
- Choose CRSF: For daily flying, recreational flying, when no ground control station is needed
- Choose MAVLink: For long-distance flights, survey missions, when real-time flight data monitoring is required
Tips
Both modes can be switched at any time. You can flash the ELRS CRSF / ELRS Mavlink firmware through the CoreWing APP.
Q3: What to do if binding fails?
A: Common causes and solutions for binding failures:
- Firmware version mismatch: Ensure the version of the transmitter module and receiver match
- Different binding passwords: Modify to the same password via WiFi
- Receiver not in binding mode: Confirm that after triple-power-on, the green light flashes rapidly
- Too far apart: During binding, place the transmitter module close to the receiver (within 1 meter)
Q4: Why must it be connected to serial port 6?
A: Serial port 6 on the CoreWing flight controller has built-in DMA (Direct Memory Access) support, which can stably handle the high-speed 460800bps data stream in MAVLink mode. Although other serial ports are hardware compatible, they lack DMA support, which can lead to data loss or communication failures.
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