How do I set up mLRS with ArduPilot for telemetry?

Connect the mLRS receiver to your flight controller's serial port, enable MAVLink telemetry in ArduPilot parameters, and use the mLRS transmitter with CRSF passthrough to wirelessly link to ground control stations like MissionPlanner. The README mentions optimizations for smoother MAVLink flow.

mLRS vs ExpressLRS for long-range drones: which is better?

mLRS excels with multi-band support and MAVLink optimizations, making it ideal for telemetry-heavy applications, while ExpressLRS focuses on low-latency RC control. mLRS offers higher serial data rates but may have steeper setup; choose based on whether you prioritize telemetry or pure control.

What's the best mLRS transmitter for 900 MHz?

The MatekSys boards are recommended for full feature support and up to 1 W power, but ExpressLRS modules like RadioMaster Ranger offer ready availability. Note that some 900 MHz gear only supports the 19 Hz 7x mode, limiting compatibility.

How to flash mLRS firmware on an ESP32 module?

Use PlatformIO with VSCode as per the ESP Development documentation, or the mLRS Flasher Web App for supported devices. Ensure your hardware is compatible and follow the guidelines in the README for target-specific steps.

Does mLRS work with Betaflight?

mLRS supports MSP protocol, which is used by Betaflight for configuration, but it's primarily optimized for INAV. You can use it with Betaflight for RC control and basic telemetry, though features like MspX are tailored for INAV.

Can I use mLRS for dual-band operation?

Yes, devices with two LoRa chips in different bands (e.g., 2.4 GHz and 915 MHz) support dual-band operation with full diversity, allowing simultaneous transmission on both bands for improved reliability, as highlighted in the features.

Open-Awesome

mLRS

GPL-3.0Cv1.4-release

Open-source LoRa-based long-range radio link for RC vehicles, providing bidirectional serial connection and full remote control.

GitHub

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What is mLRS?

mLRS is an open-source, LoRa-based long-range radio link system designed for remote-controlled vehicles like drones. It provides bidirectional serial communication and full remote control capabilities across multiple frequency bands (2.4 GHz, 915/868 MHz, 433 MHz), optimized for MAVLink and MSP protocols while maintaining high data rates.

Target Audience

RC vehicle enthusiasts, drone builders, and developers working with MAVLink-based autopilot systems (ArduPilot, PX4, INAV) who need reliable, long-range telemetry and control links.

Value Proposition

Developers choose mLRS because it's a fully open-source alternative to commercial systems, supports multiple frequency bands and hardware platforms, offers high data rates without sacrificing range, and includes specific optimizations for popular autopilot systems.

Overview

2.4 GHz & 915/868 MHz & 433 MHz/70 cm LoRa based telemetry and radio link for remote controlled vehicles

Use Cases

Best For

Building long-range FPV drone systems with reliable telemetry
Creating custom RC vehicle control links with bidirectional data
Integrating MAVLink-based autopilots with robust radio communication
Developing DIY LoRa-based radio systems for remote control applications
Replacing commercial radio links with open-source alternatives
Implementing dual-band or diversity antenna setups for improved signal reliability

Not Ideal For

Projects demanding maximum possible range at the cost of very low data rates (e.g., under 1 kB/s)
Teams seeking plug-and-play commercial systems with dedicated customer support and warranties
Applications requiring serial data rates consistently above 10 kB/s for high-bandwidth video or sensor streams
Users unfamiliar with embedded systems who prefer pre-assembled, tested hardware with simple setup

Pros & Cons

Pros

Multi-Band Flexibility

Supports 2.4 GHz, 915/868 MHz, and 433 MHz bands using Semtech LoRa chips, allowing adaptation to different regulatory environments and range vs. data rate trade-offs, as detailed in the operation modes table.

Autopilot Optimization

Includes features like MavlinkX and MSP support specifically for ArduPilot, PX4, and INAV systems, enabling smoother data flow and reduced packet loss for drone applications.

Hardware Versatility

Compatible with a wide range of platforms including STM32, ESP32, and ExpressLRS hardware, making it accessible for various budgets and DIY setups, as listed in the supported hardware section.

No Reflash Configuration

Parameters can be set via Lua script, CLI, or OLED display without reflashing firmware, improving usability and allowing on-the-fly adjustments for different models.

Full Diversity Support

Devices with two LoRa chips offer full diversity for both transmitting and receiving, significantly improving link quality in far-range scenarios, as noted in the features.

Cons

Hardware Incompatibility Issues

Some ExpressLRS and Frsky devices only support the 19 Hz 7x mode and are incompatible with MatekSys or Wio-E5 based gear, limiting cross-hardware flexibility and requiring careful selection.

Complex Initial Setup

Requires firmware flashing via a web app or IDEs like STM32CubeIDE, along with hardware assembly and configuration, which can be daunting for users without embedded systems experience.

Limited Power on Entry Hardware

Boards like Wio-E5 max out at 22 dBm transmit power, which is lower than the 1 W offered by premium options, potentially affecting range in demanding environments without upgrades.

Documentation Fragmentation

Information is spread across GitHub docs, forums, and Discord, making it harder for newcomers to find consolidated, step-by-step guidance for common tasks.

Open Source Alternative To

mLRS is an open-source alternative to the following products:

TBS Crossfire

TBS Crossfire is a long-range radio control system for drones and RC vehicles, known for its reliability and low latency.

ExpressLRS

RFD900

RFD900 is a family of long-range, high-performance radio modems designed for UAV and robotic applications, supporting MAVLink and other protocols.

OpenLRS

OpenLRS is an open-source long-range radio system for remote control applications, often used in drone and RC vehicle communication.

DragonLink

DragonLink is a long-range RC control system for drones and UAVs, providing reliable telemetry and control links for FPV flying.

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