Sirius RF Module ELRS MAVLink Telemetry for iNav

Overview

ELRS MAVLink mode enables bidirectional telemetry data transmission through the ExpressLRS RF link, allowing the RC transmitter to not only send control commands but also receive real-time aircraft status data. This article will guide you through the entire process, from firmware upgrade to ground control station connection.

1. How MAVLink Mode Works

1.1 Data Link Architecture

After enabling MAVLink functionality, the system establishes a complete bidirectional communication link:

Downlink (Telemetry): The aircraft sends data such as GPS position, barometric altitude, battery voltage, and attitude angles back to the RC transmitter through the receiver.

Uplink (Control): The RC transmitter's channel commands are sent to the aircraft through the receiver.

1.2 MAVLink vs CRSF Mode Comparison

Feature	CRSF Mode	MAVLink Mode
Communication Direction	Unidirectional (Transmitter→Aircraft)	Bidirectional (Transmitter↔Aircraft)
Transmission Content	Control signals + limited telemetry	Control signals + telemetry data
Bandwidth Requirements	Low	Medium to High
Typical Applications	Basic flight control	Long-range flight, mission planning, real-time monitoring

1.3 Practical Application Scenarios

• Real-time Monitoring: RC transmitter screen displays aircraft position, altitude, battery level, speed, and other critical data

• Remote Diagnostics: Analyze aircraft status through telemetry data to quickly locate faults

• Ground Control Station Connection: Use with ground control stations like MissionPlanner for mission planning and flight monitoring

2. Equipment List

2.1 Flight Controller

• CoreWing F405 WING V2

2.2 Wireless Communication Modules

• RF Module: Sirius 2.4G ELRS

• Receiver: SkyGuy Nano 2G4 RX

2.3 RC Transmitter

• Recommended: RadioMaster TX16S

• Compatible: Other RC transmitters supporting CRSF protocol

3. RC Transmitter Basic Settings

3.1 Enable External RF Module

1. Enter the model settings menu and find the "SETUP" page

2. Disable "Internal RF Mode"

3. Enable "External RF Mode"

4. Set "Mode" to CRSF and "Baudrate" to 5.25M

Important

Why set "Baudrate" to 5.25M?

If set to 400k, it may not be possible to enter the ExpressLRS Lua script;
If set to 1.87M, it may not be possible to set Packet Rate to F1000.

3.2 Setting Reference

Black and white screen transmitters:

Color screen transmitters:

3.3 RF Module and Receiver Binding

Important

For RF module and receiver binding tutorial, refer to: How to bind ELRS transmitter/RF module with receiver

4. Firmware Upgrade

Important Note

Before using MAVLink mode, the following firmware must be upgraded to the specified versions:

• RF Module Firmware: ≥ 3.5.6 (factory firmware)

• Receiver Firmware: ≥ 3.5.6 (factory firmware)

• Backpack Firmware: ≥ CW 1.5.4 (CoreWing customized version)

  All firmware can be upgraded through the CoreWing APP.

For information on how to update Sirius RF module and SkyGuy receiver ELRS firmware through CoreWing APP, please refer to this article:

5. MAVLink Mode Parameter Configuration

Note

When configuring RF module parameters, ensure the receiver is powered off to avoid configuration issues.

5.1 RF Module Parameter Settings

In the RC transmitter ExpressLRS script page, configure according to the following table:

Configuration Item	Setting Value	Description
Packet Rate	F1000	Frequency 1000Hz, sensitivity -104dBm
Telemetry Ratio	1:2	Ratio mode, rate 19921bps
Mode Switch	Hybrid	Hybrid mode
Link Mode	MAVLink	Telemetry protocol

5.2 Receiver Parameter Settings

1. RC transmitter enters ExpressLRS script → Select Other Devices

   

2. Select SG Nano 2G4 RX receiver

   

3. Set receiver protocol to MAVLINK, keep other parameters default

   

6. Flight Controller Configuration

6.1 Hardware Connection

UART Selection Note

CoreWing flight controller receiver connection:

• Must connect to UART6

• Reason: UART6 has built-in DMA support, can stably run at high baud rate of 460800bps

⚠️ Note: Other UARTs (like UART4) are hardware compatible but lack DMA support, MAVLink communication will not work properly.

6.2 Flight Controller Parameter Settings

Prerequisite: Open CoreWing APP, connect to the aircraft wireless module, enter the parameter settings page

1. Enter the Port Settings page

2. Find UART6, configure as follows:

   • Telemetry Output: MAVLink

   • Baud Rate: 460800

3. Click save and restart

   

Step 2: Configure Receiver

1. Enter the Receiver Settings page

2. Configure as follows:

   • Receiver Type: SERIAL

   • Serial Receiver Protocol: MAVLINK

   • Serial Invert: OFF

   • Serial Receiver Half Duplex Mode: AUTO

3. Click save and restart

   

Step 3: Verify Connection

After restarting the flight controller, enter the Receiver Channels (Real-time) page, move the sticks to check if channel values change in real-time.

If there's no change, please check the MAVLink mode parameter settings in Chapter 5.

VII. Ground Station Connection

7.1 MissionPlanner Ground Station Connection

Step 1: Configure Backpack WiFi

1. Enter ExpressLRS script on RC transmitter → Click Backpack settings

2. Set Backpack to On

3. Set Telemetry to WiFi

4. Restart the RC transmitter to apply settings

Step 2: Computer WiFi Connection

Find and connect to the ExpressLRS TX Backpack 000000 WiFi (password: expresslrs)

Step 3: MissionPlanner Connection Configuration

1. Open MissionPlanner

2. Select UDP connection mode

3. Set baud rate to 115200

4. Set port to 14550

5. Click Connect

   

   

Step 4: Verify Connection

After successful connection, click Connection Statistics to view the MAVLink telemetry link status: