How to use ExpressLRS (ELRS): Long-distance / high-speed communication protocolHere, I have summarized the basics of the procedure for controlling a drone using ExpressLRS(ELRS) : new communication protocol for radio-controlled aircrafts.
For more information on Tiny Whoops, see Introduction to FPV drone for beginner: How to fly Tiny Whoop / Racing drone .
Table of contents
What is ExpressLRS(ELRS)ExpressLRS (ELRS) is a new communication protocol for radio-controlled aircrafts that is being developed as open source. It is developed based on LoRa (SX127x / SX1280 chip), an open power-saving wireless communication technology developed by Semtech . The first firmware (Ver 0.1.0 RC1) was released in January 2021, and has been actively developed since then. The bands used are 915 MHz(FCC), 868 MHz(EU) and 2.4 GHz. It has a long radio wave range ( about 10km - 30km at 2.4GHz output 100mW ) and enables high-speed communication with low latency (adjustable in the range of 50Hz-250Hz (868/915 MHz) / 500Hz (2.4GHz)). Can be used with transmitters that support OpenTX/EdgeTX LUA scripts or TBS Crossfire (CRSF). Each manufacturer is releasing compatible products one after another. However, since it is a specification under development, improved versions of each product and firmware are appearing one after another, and some research is required to master it.
ExpressLRS official site holds competition for the range of radio waves . If you get good results, why don't you try to enter?
What is TX BackpackIt is one of the optional functions of Express LRS. You can wirelessly control FPV-related devices from the radio using a protocol called espnow. For example, you can change the reception frequency of FPV goggles with the radio. To use this feature, both the ExpressLRS transmitter and thecontrolling device must have ESP8285 chip. This ESP8285 chip is called "TX-Backpack".
ExpressLRS(ELRS) setting procedureHere, we will explain step by step how to set the transmitter / receiver of ExpressLRS (ELRS).
To use ELRS transmitter, OpenTX on the radio must be upgraded to 2.3.12 or later. (Available in all versions of EdgeTX)
- Install ExpressLRS Configurator
- Install the tool "ExpressLRS Configurator" on your computer. This is a tool used to configure, build and update transmitter and receiver firmware.
- Attach ExpressLRS transmitter to radio
- If you use an external ELRS transmitter, install it in the module bay of your radio. Then store ELRS Lua script in "\SCRIPTS\TOOLS\" folder of SD card in the radio. And create "MODEL" of the drone you want to bind in radio (OpenTX/EdgeTX).
- Update ExpressLRS transmitter firmware
- ExpressLRS is a protocol under development, so it is being upgraded frequently. There are two ways to update, one is to use a USB cable (UART) and the other is to use Wifi.
- Set up ExpressLRS transmitter
- You can configure ExpressLRS transmitter by launching ELRS Lua script in radio. You can change packet rate and output power .e.t.c,. If the transmitter itself has a display and joystick, you can also use it instead of Lua script to configure it.
- Update ExpressLRS receiver firmware
- Update receiver firmware to match transmitter version. For external receivers connected via UART, use ExpressLRS Configurator to update. For receivers built in FC (Flight Controller) connected via SPI, receiver firmware is included in the firmware of FC. In this case, use Betaflight Configurator , to update the FC firmware by upgrading it.
- Bind transmitter and receiver
- There are two ways to bind, one is to use "watchword" called "Binding Phrase" and the other is to bind manually. And the setting method differs depending on whether you are using external receiver or FC (Flight Controller) built in receiver.