Receiver using mLRS firmware for MSP communication - iNav firmware

I. Working Principle

After flashing the CoreWing Sirius high-frequency module with mLRS firmware, it integrates remote control and telemetry functions into a single device, achieving telemetry-control integration with the following advantages:

1. Device Simplification: Only one module needs to be configured to complete both remote control signal uplink and MSP bidirectional transparent communication, reducing device count and connection complexity
2. Strong Anti-Interference Capability: Remote control signals and MSP data share the same radio link, reducing mutual interference
3. USB Transparent Transmission: Connect the high-frequency module to a computer via USB data cable for direct parameter tuning using iNav configurator

II. Device Preparation

2.1 Flight Controller

• CoreWing F405 WING V2

2.2 Wireless Communication Module

• High-frequency module: Sirius 2.4G (requires mLRS firmware)
• Receiver: SkyGuy Nano 2G4 RX (requires mLRS firmware)

Tips

The high-frequency module and receiver must first be flashed with mLRS firmware. Refer to the following article for firmware upgrade:

Sirius High-frequency Module ELRS/mLRS Firmware Switching Tutorial

2.3 RC Transmitter

• Recommended: RadioMaster TX16S
• Compatible: Other RC transmitters that support external modules

III. RC Transmitter Setup and Lua Script Import

3.1 RC Transmitter External RF Parameter Setup

Important

mLRS officially only supports 400k baud rate! If using the ELRS 1.87M/3.75M/5.25M baud rate, it will not work properly.

1. Enter the RC transmitter MODEL SETUP
2. Disable Internal RF
3. Enable External RF
4. Set Mode to CRSF
5. Set Baudrate to 400k

Color Screen Transmitter

Black and White Screen Transmitter

3.2 Import mLRS Lua Script

mLRS Lua Script Import Tutorial

mLRS Lua Script Download:

Color Screen Transmitter

• mLRS.lua

Black and White Screen Transmitter

• mLRS-bw.lua

IV. Receiver Connection to Flight Controller

Important

CoreWing F405 WING V2 Flight Controller to Receiver Connection Method:

1. Interface Requirement: Must connect to Serial 6
2. Reason:
   • Serial 6 has built-in DMA support
   • Supports MSP transparent communication

V. High-frequency Module and Receiver Binding

Click to view mLRS high-frequency module and receiver binding

VI. mLRS Parameter Setup

6.1 High-frequency Module Parameter Setup

Enter the mLRS Lua script and modify the following parameters:

Warning

Remember to click Save to save the parameters!!!

Color Screen Transmitter

Click Edit Tx to enter high-frequency module parameter editing

Black and White Screen Transmitter

Click next to find Tx-related parameters

Parameter	Set to
Tx Ser Dest	serial
Tx Ser Baudrate	115200

Tips

Tx Ser Dest Setting Description:

• serial: Enable high-frequency module USB output, allowing connection to computer via USB data cable
• serial2: Enable BLE Bluetooth function, USB connection cannot be used

This article requires using a USB data cable to connect to the iNav configurator, so set to serial.

6.2 Receiver Parameter Setup

Enter the mLRS Lua script and modify the following parameters:

Warning

Remember to click Save to save the parameters!!!

Color Screen Transmitter

Click Edit Rx to enter receiver parameter editing

Black and White Screen Transmitter

Click next to find Rx-related parameters

Parameter	Set to
Rx Ser Baudrate	115200
Rx Ser Link Mode	mspX
Rx Snd RcChannel	rc_override

Tips

MSP Transparent Mode Description:

• mspX: Enable MSP transparent function, supporting iNav configurator communication with flight controller through the high-frequency module
• Baud rate set to 115200 to match MSP communication standards

VII. Flight Controller Parameter Setup

1. Connect the flight controller to the computer using a data cable

2. Open iNav ground control station

3. Modify the following parameter settings

VIII. Ground Control Station Connection Setup

8.1 USB Data Cable Connection

1. Connect the high-frequency module to the computer using a USB data cable

2. Open iNav ground control station

3. In the port selection dropdown menu, find the serial port corresponding to the high-frequency module (usually displayed as COMx or /dev/ttyUSBx)

4. Select baud rate 115200

5. Click the Connect button

6. Check if the ground control station is receiving data

9. Q&A

Q1: What is the difference between setting Tx Ser Dest to serial and serial2?

A1:

• serial: Enables high-frequency USB output, allowing connection to a computer ground control station via USB cable, but BLE Bluetooth cannot be used.
• serial2: Enables BLE Bluetooth functionality, allowing connection to a mobile phone app via Bluetooth, but USB cable connection cannot be used.

Q2: Why must Rx Ser Baudrate be set to 115200?

A2: The standard communication baud rate for the MSP protocol is 115200, which differs from the MAVLink (57600) used by ArduPilot.

Q3: How to confirm that MSP passthrough is working properly?

A3: After connecting to the iNav configurator, if you can successfully read flight controller parameters and display flight data in real-time, it indicates that the MSP passthrough function is working properly.

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