June 10, 2021

1051 words 5 mins read



STM32/ESP32/ESP8285-based High-Performance Radio Link for RC applications

repo name ExpressLRS/ExpressLRS
repo link https://github.com/ExpressLRS/ExpressLRS
language C++
size (curr.) 319825 kB
stars (curr.) 911
created 2018-10-01
license GNU General Public License v3.0


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Support ExpressLRS

If you would like to support the development of ExpressLRS please feel free to make a small donation. This helps us buy hardware for porting, development and prototyping. Show your support for which new features you want added by leaving a message when you donate Donate

Quick Start Guide

If you have hardware that you want to flash, please refer to our guides on the wiki, and our FAQ

Build Status Release License Stars Chat

ExpressLRS is an open source RC link for RC applications. It is based on the fantastic semtech SX127x/SX1280 hardware combined with an ESP8285, ESP32 or STM32. ExpressLRS supports a wide range of hardware platforms as well as both 900 MHz and 2.4 GHz frequency options. ExpressLRS uses LoRa modulation as well as reduced packet size to achieve best in class range and latency compared to current commercial offerings.

ExpressLRS can run at various packet rates, up to 500hz or down to 25hz depending on your preference of range or low latency. At 900 MHz a maximum of 200 Hz packet rate is supported. At 2.4 GHz a blistering 500 Hz is currently supported with a custom openTX binary with future plans to extend this to 1000 Hz.

ExpressLRS supports telemetry as optional feature. Enabling telemetry also adds support for the betaflight lua script.

ExpressLRS can be flashed into existing Frsky R9M hardware (RX and TX), Jumper R900 RXs, SiYi FM30 Hardware (Rx and TX), GHOST hardware (RX and TX) or Custom PCBs can be made if you enjoy tinkering. Happy Model released official ExpressLRS hardware (RX and TX) and several other manufacturers are preparing to offer offical ELRS hardware soon so stay tuned.


ExpressLRS aims to achieve the best possible link performance for both latency and range. This is achieved with an optimised over the air packet structure. This compromise allows ExpressLRS to achieve simultaneous better latency AND range compared to other options in the market. For example, ExpressLRS 2.4GHz 150Hz mode offers the same range as GHST Normal while delivering near triple the packet update rate. Similarly, ExpressLRS 900MHz 200Hz will dramatically out-range Crossfire 150Hz and ExpressLRS 50Hz will out-range Crossfire 50Hz watt per watt.

2.4GHz Comparison RangeVsPacketRate

More information can be found in the wiki.

Starting Out

After taking a look at the supported Hardware and making sure you have the required hardware, the Quick Start Guide is written to walk through the process of flashing ELRS for the first time

Supported Hardware

900 MHz Hardware:

2.4 GHz Hardware:

  • TX
    • DIY JR Bay (Full Support, 27dBm, supports WiFi Updates)
    • DIY Slim TX (Full Support, 27dBm, supports Wifi Updates, fits Slim Bay)
    • DIY Slimmer TX (Full Support, 27dBm, supports Wifi Updates, fits Slim Bay)
    • GHOST TX (Full Support, 250 mW output power, OLED support in ELRS v1.1)
    • GHOST TX Lite (Full Support, 250 mW output power, OLED support in ELRS v1.1)
    • HappyModel TX (Full Support, 250 mW output power)
  • RX
    • GHOST Atto (Full Support, Initial flashing with STLINK then both STLINK and BF passthrough)
    • GHOST Zepto (Full Support, Initial flashing with STLINK then both STLINK and BF passthrough)
    • DIY 20x20 RX (Full Support, easy to build. WiFi Updating)
    • DIY Nano RX (Full Support, CRSF Nano Footprint, WiFi Updating)
    • DIY Nano CCG RX (Full Support, CRSF Nano Pinout, STM32 Based)
    • DIY Nano Ceramic RX (Full Support, CRSF Nano Footprint, WiFi Updating, Built in antenna)
    • HappyModel PP RX (Full Support, CRSF Nano Pinout, STM32 Based)
    • HappyModel EP1/EP2 RX (Full Support, CRSF Nano Pinout, ESP8285 Based, WiFi Updating)

For a more exhaustive list refer to the Supported Hardware page on the wiki

Long Range Competition

One of the most frequently asked questions that gets asked by people who are interested in, but haven’t yet tried ELRS is “How far does it go, and at what packet rate?”

The following table is a leaderboard of the current record holder for each packet rate, and the longest distance from home. Note that not every flight resulted in a failsafe at max range, so the link may go (much) futher in some cases.


Anyone can add an entry to the table, and entries should include the:

  • Max distance from home
  • RF freq (900 / 2.4)
  • Packet rate
  • Power level
  • If the link failsafed at max range
  • The pilot name
  • A link to your DVR on youtube (DVR is essential to compete, sorry, no keyboard claims)

Current Leaderboard

Max Dist. Freq Pkt Rate TX Power Failsafe at Max Range? Pilot Handle Link to DVR
40Km 900M 50HZ 10mW No Snipes https://www.youtube.com/watch?v=0QWN9qWoSYY
35Km 2.4G 250HZ 100mW No Snipes https://youtu.be/dBmTRhgVcyY
30Km 900M 50HZ 1W No Snipes https://www.youtube.com/watch?v=SbWvFIpVkto
10Km 2.4G 250HZ 100mW No Snipes https://youtu.be/dJYfWLtXVg8
6Km 900M 100HZ 50mW No Snipes https://youtu.be/kN89mINbmQc?t=58
6Km 2.4G 500HZ 250mW No Spec https://www.youtube.com/watch?v=bVJaiqJq8gY
4.77Km 900M 200HZ 250mW No DaBit https://www.youtube.com/watch?v=k0lY0XwB6Ko
3Km 2.4G (ceramic chip antenna RX) 500HZ 100mW No Spec https://www.youtube.com/watch?v=kfa6ugX46n8
2.28Km 900M 50HZ 10mW No Mike Malagoli https://www.youtube.com/watch?v=qi4OygUAZxA&t=75s

Check the wiki page for previous leaders!

The use and operation of this type of device may require a license and some countries may forbid its use. It is entirely up to the end user to ensure compliance with local regulations. This is experimental software/hardware and there is no guarantee of stability or reliability. USE AT YOUR OWN RISK


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