A Full Information to Flashing and Setting Up ExpressLRS

ExpressLRS is an open-source RC system that has gained recognition resulting from its affordability, ultra-low latency, and long-range capabilities. Nonetheless, establishing ExpressLRS might be fairly a frightening job for newcomers. That’s why on this tutorial, we are going to information you thru the method of flashing and establishing ExpressLRS 2.4GHz transmitter module and receiver on OpenTX/EdgeTX radio and Betaflight.

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New to ExpressLRS? This text explains the benefits of ExpressLRS over different radio management methods and why I desire to make use of 2.4GHz than 900MHz.

ExpressLRS 2.4GHz {Hardware} Choice

All transmitters and receivers with ExpressLRS firmware are appropriate regardless the model.

Radios with Constructed-in ELRS

Getting a radio with ExpressLRS built-in means you’ll be able to get pleasure from this nice radio management hyperlink with out the necessity for a further module. It simplifies the setup course of and reduces the price of upgrading your radio system. Some radios with inner modules solely go as much as 150-250mW, whereas some could go as much as 1W.

Transmitter Module

When you’ve got a radio with out built-in ExpressLRS, you have to to buy an ExpressLRS transmitter module to be able to use the system. Your radio will need to have a appropriate module bay to put in this module to.

Betafpv Expresslrs Elrs Micro Tx Module Display Screen

Selecting a transmitter module might sound daunting as a result of abundance of choices out there. Nonetheless, most of them are primarily based on the identical open supply design by ExpressLRS. The primary variations lie within the construct high quality, options reminiscent of display, most output energy, and cooling. Go for one of many respected model featured beneath.

The transmitter module suits into the exterior JR module bay. Smaller radios may need lite module bay, you have to to get the best dimension module.

Different full dimension module choices:

Different Lite module choices:

TX Antenna Upgrades

Inventory antennas typically have decrease good points as they’re designed for normal use, and their construct high quality just isn’t all the time the most effective. To extend your vary, take into account upgrading to an aftermarket antenna with higher high quality and better acquire. With a variety of shapes and sizes, yow will discover one which fits your wants and surroundings.


All ExpressLRS receivers and transmitter modules are cross-compatible, no matter model, since they’re primarily based on the identical open supply design. The primary variations are construct high quality, dimension, and WiFi help for firmware updates and configuration. Lastly, take into account the kind of antenna that comes with the receiver, as some have a built-in antenna which is extra compact, whereas others include a U.FL connector for an exterior antenna which usually present higher vary.

On the subject of {hardware}, take into account receivers with “PA” and “LNA” for higher vary efficiency. Search for receivers with “TCXO” as they provide a extra secure hyperlink.

PA (Energy Amplifier) and LNA (Low-Noise Amplifier) are parts that enhance the efficiency of the receiver. The PA offers a extra stable telemetry hyperlink for long-range flying, whereas the LNA considerably will increase the sensitivity of the receiver and provides you higher vary.

TCXO (Temperature Compensated Crystal Oscillator) is a kind of oscillator that gives a much more secure frequency with a a lot wider temperature vary. That is necessary as a result of when parts warmth up or calm down, it might probably trigger frequency shift within the oscillator, and if that frequency shift is outdoors of a sure margin, your receiver will lose reference to the transmitter. So, having a receiver with a TCXO will guarantee optimum efficiency and reliability.

Variety Receivers

Variety provides higher vary and sign power. There are two forms of range receivers. “Antenna Variety” makes use of a single radio chip related to 2 antennas, whereas “True Variety” makes use of 2 impartial RF chips, every with its personal antenna. True Variety is dearer than Antenna Variety, however makes more practical use of the dual-antenna setups subsequently offers higher efficiency. True range receivers additionally help Gemini Mode. Extra information on Variety Receivers.

PWM Receivers

Different receiver choices:

RX Antenna Substitute

Is It Essential to Replace ExpressLRS Firmware?

You don’t must however you must.

With every replace, the open-source mission offers bug fixes and efficiency enhancements, making certain optimum performance.

ELRS firmware model makes use of a three-part quantity system: A.B.C

  • A: main model quantity
  • B: minor model quantity
  • C: patch quantity

All releases with the identical main model quantity are cross-compatible, however not with totally different main variations. As an illustration, 2.0 will work with 2.1, 2.2, 2.5 and so forth, however 2.x firmware gained’t bind with 3.x.

Flash EdgeTX

Edgetx Tutorial Feature Image Oscarliang

When you’ve got OpenTX in your radio, take into account flashing EdgeTX. EdgeTX is a more recent, extra cutting-edge fork of OpenTX with frequent updates and plenty of further options. Plus, it provides particular advantages to be used with ExpressLRS, reminiscent of 500Hz gimbal polling. Take a look at our information for flashing EdgeTX to your radio.

If need to proceed to make use of OpenTX, be sure you replace to 2.3.12 or newer earlier than making an attempt to flash ELRS firmware to your transmitter module (the brand new variations help CRSFShot which is crucial for ELRS to work). Our step-by-step information for flashing OpenTX may help you get began.

Easy methods to verify whether or not you might have OpenTX or EdgeTX on the radio? Press the “SYS” button, then press the PAGE button till you’re on the final web page “VERSION”, and you’ll see the firmware and model there.

Edgetx Firmware Version Sys Vers Number

Obtain ExpressLRS Configurator

ExpressLRS Configurator lets you construct, compile and flash firmware for the ExpressLRS receivers and transmitter module.

Obtain: https://github.com/ExpressLRS/ExpressLRS-Configurator/releases/newest

For Home windows, click on the hyperlink with this title: ExpressLRS-Configurator-Setup-X.X.X.exe

Your laptop have to be related to the web whereas utilizing the Configurator.

Expresslrs Elrs Configurator V1.01 Flash Build Rx Firmware

Set up LUA Script

A LUA script is a mini program on the radio. The ExpressLRS LUA script lets you configure the system, reminiscent of altering radio hyperlink settings, activating binding mode, enabling WiFi and so forth.

EdgeTX usually comes with ExpressLRS LUA script and also you don’t must do something. Nonetheless once you replace ExpressLRS, it’s a good suggestion to replace the LUA script as effectively.

Yow will discover and open the LUA script by urgent the SYS button, and choose “ExpressLRS”.

Expresslrs Elrs Lua Script V2 Radio Tx16s Edgetx

If the LUA script just isn’t there, you’ll be able to obtain it within the ExpressLRS Configurator by choosing the newest launch model and any goal, and the “Obtain LUA Script” button will seem.

Expresslrs Elrs Configurator Download Lua Script V3 Before Flash

The downloaded file ought to have “.lua” file extension, put that file on this listing in your radio’s SD card: SCRIPTSTOOLS

Expresslrs Download Lua Script V3 Sd Card Tool

Earlier than continuing, it’s important to get your radio speaking to the ExpressLRS TX module (let it’s inner module or exterior module). In your radio, go to Mannequin setup, scroll right down to “Inner RF” and choose “CRSF” in Mode. When you’ve got an exterior module, do that below “Exterior RF” and depart Inner RF to OFF. No want to alter any of the choices.

If yours is a brand new radio and also you’ve by no means setup a mannequin profile earlier than, I encourage you to check out make a mannequin profile from scratch: https://oscarliang.com/create-new-model-profile-edgetx/

Create New Model Profile Edgetx 9 Internal External Rf

Establish {Hardware} and Firmware Model

There are a lot of producers making receivers and transmitter modules for ExpressLRS. You could know the model and mannequin of the {hardware} to be able to flash the right firmware. Flashing the incorrect firmware will fail the method, it’d even brick your system.

The best approach to verify is by going to the WiFi webpage. Right here’s do it.

Firstly, allow WiFi in your system by going to the ExpressLRS LUA script, choose WiFi Connectivity.

Expresslrs Elrs Lua Script V2 Interface App

Then allow WiFi on the specified system.

Expresslrs Elrs Lua Script V2 Wifi

For receivers, it’s also possible to simply wait 60 seconds with out turning in your transmitter, and it’ll go into WiFi mode robotically.

In your laptop computer, you must see a WiFi community known as ExpressLRS TX (or ExpressLRS RX). Hook up with this community, the password is expresslrs.

Expresslrs Elrs Wifi Network

Open the browser, and kind within the deal with bar, it can open up a web site which can inform you which firmware goal it’s utilizing. It’s also possible to verify the firmware model right here.

Expresslrs Wifi Webpage Shows Device Target Firmware Version

If you happen to beforehand setup the system to affix your property WiFi community, then you definitely gained’t see this WiFi community. As an alternative, keep related to your property WiFi, and enter http://elrs_rx.native/ or http://elrs_tx.native/ within the browser deal with bar.

Alternatively, for ELRS transmitter modules, it’s also possible to discover the maker, mannequin and firmware model within the LUA script (on the high and backside of the web page). For receivers, go to “Different Units” within the LUA script, and click on on the receiver, firmware model needs to be displayed there (solely works since V3).

Expresslrs Bluetooth Joystick Lua Script Ble

Compile and Flash TX Firmware

You possibly can flash the TX module utilizing one among these strategies:

I discovered WiFi to be the simpler and extra dependable methodology, I’ll show do it right here. It’s also possible to use USB which I’ll clarify shortly later.

Constructing ELRS TX Firmware

Earlier than flashing, it’s essential to compile the firmware first utilizing the ExpressLRS Configurator.

Expresslrs Elrs Configurator V3.0 Flash Build Tx Firmware

Underneath Releases, select the newest firmware.

Underneath System Goal, choose the model, and system. On this instance, I’ve the BetaFPV Micro 1W TX, so the Goal System picks could be:

  • System Class: BetaFPV 2.4 GHz
  • System: BetaFPV 2400 TX Micro 1000mW

Let me clarify what a few of the settings imply.

Regulatory Domains – relying on the place you’re, the second possibility “EU_CE” is for folks within the EU, that is often known as LBT. Anyplace else you’ll be able to choose the primary possibility “ISM”, often known as FCC.

What’s FCC and LBT and the way does it have an effect on efficiency?

FCC (Federal Communications Fee) and LBT (Pay attention Earlier than Discuss) are regulatory requirements for radio methods. FCC is globally accepted, whereas LBT is particular to Europe and requires a radio to verify for different transmissions earlier than transmitting itself. Whereas FCC usually permits for constant energy output, LBT could cut back output energy resulting from its “pay attention” requirement, doubtlessly affecting efficiency.

Binding Phrase – it’s like the important thing to your automotive, be inventive and make a singular phrase, so folks you fly with don’t by chance use the identical phrase and trigger issues. Observe that different folks CAN management your drone in the event that they use the identical binding phrase.

Community => Auto WiFi On Interval: what number of seconds it activates WiFi mode if no radio hyperlink is established. Default is 60 however I personally desire to set it to twenty. If the receiver goes into WiFi mode you simply must unplug LiPo and plug in once more.

Community => HOME_WIFI: See right here for extra element.

The Configurator remembers your selections, so that you don’t want to pick them once more the subsequent time.

Flash TX Firmware through WiFI

As soon as you’re proud of the firmware choices, choose WiFi below Flashing methodology.

Click on the BUILD button (NOT Construct and Flash) to compile the firmware. It may well take just a few minutes relying in your web velocity.

When it’s achieved, a home windows ought to pop up containing the firmware file, named “firmware.bin“.

Expresslrs Firmware Compile File

Plug within the TX module to your radio module bay and energy on radio.

Betafpv Expresslrs Elrs Micro Tx Module Jr Bay Tx16s

In your radio, setup a brand new mannequin profile, in Mannequin Setup, below Exterior RF, choose CRSF in Mode. In case your module is an inner module (i.e. constructed into the radio), then it’s essential to choose CRSF below Inner RF.

Open the LUA script by urgent the SYS button, below Instruments, choose ExpressLRS.

Expresslrs Elrs Lua Script V2 Radio Tx16s Edgetx

Choose “WiFi Connectivity“.

Expresslrs Elrs Lua Script V2 Interface App

Choose “Allow WiFi” and depart the radio powered on.

Expresslrs Elrs Lua Script V2 Wifi

Go to your laptop’s WiFi, you must discover a new community known as “ExpressLRS TX Module“. The WiFi password is: expresslrs

Open browser and go to

Click on “Select File” and choose “firmware.bin” generated from the ExpressLRS Configurator earlier.

Click on Replace. That’s it!

Flash TX Firmware through UART/USB

You should use the USB port on the TX module to flash firmware.

You would possibly want to put in CP210x Driver (Obtain: https://www.silabs.com/builders/usb-to-uart-bridge-vcp-drivers). I attempted customary home windows driver because it comes with an installer, model 6.7.6 appears to work advantageous.

This course of will work for nearly any ExpressLRS transmit module. On some newer modules, you’ll be able to simply plug within the USB cable and it’ll flash immediately. Nonetheless some older modules have dip switches, it’s essential to put them in the best place to be able to flash. Seek the advice of the handbook should you see these switches. For instance the BetaFPV Micro TX module has these dip switches.

Betafpv Elrs Micro Tx Module 1w Edition Dip Switch

Plug within the USB cable to the TX module, a brand new COM port ought to seem in your laptop.

Within the ExpressLRS Configurator, below Flashing methodology, choose UART. When you’re prepared, click on the BUILD and FLASH button (not Construct). The flashing will take a couple of minutes.

Join ELRS Receiver to FC

Right here’s the pin-out of the PP, EP1 and EP2 receivers.

Join TX and RX pins to any spare UART in your flight controller. DO NOT use soft-serial as a result of it’s too sluggish.

Join TX to RX, and RX to TX.

Right here’s the pinout for the BetaFPV ELRS Nano RX.

Betafpv Expresslrs Nano Rx Close Up

Construct and Flash RX Firmware

For receivers with WiFi built-in, you’ll be able to flash firmware through WiFi, similar to flashing the TX. However personally I discovered utilizing Betaflight Passthrough simpler for flashing RX, and I’ll show it right here.

Open ExpressLRS Configurator, choose the identical firmware model as your TX module and select the system goal primarily based on the model and receiver sort. For instance:

  • For PP receiver, the System is: HappyModel PP 2400 RX
  • For EP1 and EP2 receivers, the System is: HappyModel EP 2400 RX

Be sure that to set the binding phrase as your TX, your RX will simply bind with the TX robotically after flashing firmware. If you happen to don’t set a binding phrase, you’ll be able to bind it manually as described right here.

Expresslrs Elrs Configurator V2.5 Flash Build Rx Firmware

Flash RX Firmware through Betaflight Passthrough

Earlier than continuing, make certain to configure Betaflight first as described on this part.

Now join the USB cable to your quad to energy the FC and RX.

In ExpressLRS Configurator, select the COM port of the FC (if undecided, verify the COM port in Betaflight Configurator, however keep in mind to disconnect/shut it afterwards).

Hit BUILD & FLASH. It would take a couple of minutes.

Flash RX Firmware through WiFi

Principally the steps are the identical as flashing the TX module through WiFi. Some receivers don’t have WiFi functionality, so be sure you verify earlier than continuing.

Within the ExpressLRS Configurator, hit the BUILD button to compile the firmware.bin file.

By default, should you energy the receiver with out turning on the radio, after 60 seconds it can enter WiFi mode (LED might be flashing quickly to point that). The RX’s WiFi sign is pretty weak so place the RX near the WiFi antenna to your laptop.

Hook up with the WiFi community “ExpressLRS RX“. The WiFi password is: expresslrs

Go to in your browser, and add the firmware file.

Flash RX Firmware through UART

Within the uncommon occasion, if neither of the above strategies work, you’ll be able to attempt UART flashing as described right here.

Flashing RX through FDTI

If for no matter purpose you bricked your RX, which might occur should you misplaced energy or connection throughout flashing, you’ll be able to deliver it again by flashing through FDTI: https://www.expresslrs.org/2.0/quick-start/receivers/hmep2400/#flashing-via-ftdi.

Flashing SPI ExpressLRS Receiver

Some whoop flight controllers have ELRS receiver built-in on the identical board, and it usually makes use of SPI connection as an alternative of an UART connection. An excellent instance could be the Happymodel X12 AIO 5in1 FC within the Mobula7 ELRS Version.

Happymodel Mobula7 1s Bnf Tiny Whoop Flight Controller Happymodel X12 Aio Fc 12a Esc

The great factor is that you just don’t want to fret about wiring because the receiver is simply a part of the flight controller.

However flashing the receiver is a bit tough. In an effort to replace the RX firmware, it’s important to flash the newest Betaflight firmware, as a result of ExpressLRS firmware is embedded within the Betaflight firmware for that flight controller. All of the construct choices (reminiscent of area, swap mode and so forth) are in Betaflight CLI (sort “get expresslrs” will checklist all of them).

To verify you probably have a SPI ELRS receiver, merely go to Betaflight Configurator, Receiver tab, and see if it’s set to SPI RX / ExpressLRS.

Betaflight Configurator Receiver Spi Expresslrs

Binding Receiver

There’s no bind button on ELRS receivers (if there’s a button, it’s the boot button). There are 3 methods to bind your receivers to a transmitter as defined on this tutorial: https://oscarliang.com/bind-expresslrs-receivers/

ExpressLRS transmitter and receiver might be sure utilizing bind phrase, which you’ll be able to set when compiling the firmware on your gadgets, or you’ll be able to enter this within the Internet UI. Each receiver and transmitter will need to have the identical binding phrase to work.

When the receiver first powers up, it appears for the transmitter with the matching binding phrase. As soon as the connection is established it can get synced up, and one other system gained’t have the ability to hook up with it.

Nonetheless if another person makes use of the identical bind phrase on their radio and has a stronger sign than you, it’s attainable your receiver will bind to theirs first, and so they can take management of your quad. This might be a particularly uncommon situation and even when somebody needs to do that on function it could be very onerous to tug off, nonetheless, it’s greatest should you hold your bind phrase a secret and as distinctive as attainable.

It’s also possible to bind a transmitter and receiver manually by placing them in Bind Mode. However this can solely work if the receiver doesn’t have a bind phrase set.

Receiver LED Standing Indicator

Monochrome LED that means:

  • Stable LED means bind efficiently or connection established
  • Double-flash means it’s in bind mode
  • Flash slowly means ready for TX module connection
  • Flash quick means it’s in WIFI hotspot mode, you’ll be able to hook up with the RX’s WiFi community to improve RX firmware by visiting in your browser (password: expresslrs)
  • Triple blink then pause – Mannequin Mismatch (make certain Mannequin Match is both disabled on each TX/RX, or the ID are the identical at each ends)

Shade RGB LED that means:

  • Rainbow fade impact: Beginning up
  • Inexperienced heartbeat: Internet replace mode enabled
  • Sluggish blink: Ready for connection from transmitter
  • Pink speedy flashing: Radio chip not detected
  • Orange double blink then pause: Binding mode enabled
  • Orange triple blink then pause: Related to transmitter, however mismatched model-match configuration
  • Stable single shade: Related to a transmitter, shade signifies packet fee and mode

Betaflight Setup for ExpressLRS Receiver

To setup ExpressLRS RX’s:

Go to the “Ports” tab within the Betaflight configurator, and allow “Serial RX” for the UART you’ve related the ELRS receiver to. Press “Save”.

Within the Receiver tab, below the “Receiver” Part, choose “Serial (through UART)“ because the Receiver Mode, and choose “CRSF” in Serial Receiver Supplier. Allow “Telemetry”, and click on the “Save” button.

Setup Betaflight Receiver Mode Provider Telemetry

Your RX needs to be working now.

To confirm, return to the “Receiver” tab, you must see response from stick motion. If the channels are within the incorrect order, simply attempt a distinct “Channel Map”.

Examine if the tip factors (1000 or evenly decrease / 2000 or evenly greater) and mid factors (1500) are right, see this information on alter in the event that they aren’t right.

To verify Telemetry is working, go to the Telemetry web page within the radio, and choose the choice “Delete all sensors“, then “Uncover new sensors”.

Asterisk flashing means telemetry is updating.

expresslrs telemetry opentx

Within the Modes tab, you MUST set AUX 1 as your arm swap (AUX1 is all the time a 2-position swap, designed particularly for arming in ExpressLRS).

Show LQ and RSSI in OSD

Additional Studying: What are LQ and RSSI?

In a nutshell:

  • RSSI – Sign power, how loud the sign is (worth from -130dBm to 0dBm)
  • LQ – Hyperlink High quality, how effectively your receiver can perceive the sign (worth from 100% to 0%)

Each indicators are helpful, but when it’s important to decide one, LQ might be extra necessary.

To show LQ correctly you must use the newest model of Betaflight (4.2 or newer), the place they launched a brand new RFMD:LQ% format for the LQ OSD component.

  • Within the Receiver tab, Disable RSSI_ADC, set RSSI Channel to Disable
  • Within the OSD tab, allow Hyperlink High quality and RSSI in dBm

It’s helpful to have each measurements. For instance:

  • Excessive LQ, excessive RSSI = wholesome radio hyperlink
  • Low LQ, excessive RSSI = noisy RF surroundings
  • Excessive LQ, low RSSI = In case you are very far-off, warning is required as you’re approaching the tip of vary; If the receiver may be very near the transmitter, that may be an indicator of antenna drawback
  • Low LQ, low RSSI = the tip of vary, you must flip again as failsafe is more likely to occur

Antenna Mounting

My suggestion is to mount your RX antenna vertically if attainable. It’s also possible to mount it horizontally should you solely fly quick vary. See this publish for extra element.

Setup Failsafe

Digital RC protocols usually incorporates a failsafe flag within the information packet that the flight controller can detect robotically, so there’s no want for handbook setup on the radio. Nonetheless, it’s essential to evaluate the Failsafe tab in Betaflight and decide what motion the drone ought to take within the occasion of a failsafe.

To make sure failsafe is working correctly, conduct a bench take a look at. Take away all propellers, plug within the battery, arm the quad, and switch off the radio. The default failsafe settings in Betaflight ought to cease all motors from spinning inside a few seconds. Be ready to unplug the battery in case of any points.

ELRS LUA Script Settings

There are 3 most important settings you must know in ExpressLRS Lua script: Packet Charge, Telem Ratio (telemetry ratio) and TX Energy.

Expresslrs Elrs Lua Script V2 Interface App

TX Energy

Out there choices are: 25mW, 50mW, 100mW, 250mW, 500mW and 1W. Observe that with EU LBT firmware, the RF energy is proscribed to 100mW.

Some modules solely help as much as 250mW, whereas some are able to as much as 1W. Assessments have proven that simply 2.4GHz at 100mW can obtain 33km vary, which may simply outperform most 5.8GHz video hyperlinks, so that you don’t all the time have to make use of the very best energy out there. To not point out greater energy consumption can considerably cut back radio battery life, and improve the chance of overheating with out correct cooling. With RF energy greater than 250mW, turning on the fan is advisable, so this by setting fan threshold to 250mW.

By enabling the choice Dynamic Energy, it permits the system to robotically alter output energy primarily based on sign power. Dynamic Energy makes use of SNR (sign to noise ratio) as an alternative of RSSI to find out energy as RSSI doesn’t issue within the noise ground or if the receiver has an amplifier. This will doubtlessly save battery life as it can decrease the facility when the receiver is shut by, it solely will increase energy when it’s wanted. When you’ve got Dynamic Energy on, MAX Energy would be the higher restrict.

The suitable energy stage on your FPV drone is dependent upon the specified packet fee and vary. Operating ExpressLRS at 50Hz can present extraordinary vary, even at 100mW. Nonetheless, should you plan to make use of the next packet fee, like 500Hz, your vary might be considerably decreased, and it’s possible you’ll want extra output energy to keep up the identical vary. Familiarize your self with dB and you’ll carry out calculations utilizing receiver sensitivity and output energy to find out the vary distinction between numerous packet charges and energy ranges, this can assist you decide. 250mW needs to be sufficient for most individuals flying inside a few miles of vary even at 500Hz, however after all greater energy offers you higher sign penetration too, not simply vary. Regardless the facility, if you would like essentially the most dependable hyperlink or need to fly lengthy vary, it’s usually advisable to stay to a decrease packet fee reminiscent of 50Hz because it provides greater sign sensitivity.

Packet Charge

Packet fee is the variety of information packets transmitted per second. It’s a tradeoff between vary and latency, you simply can’t have each. Larger packet fee has decrease latency, however much less vary.

In ELRS V3, the packet fee modes out there are:

  • 500Hz, 250Hz, 150Hz, 50Hz – These are the conventional modes, utilizing LoRa modulation which has longer vary and higher resistance to RF interference.
  • F1000, F500 – These are F modes, or FLRC, they provide quicker modulation and decrease latency, however shorter vary than the conventional modes. It helps 500Hz and 1000Hz. Nice for racers. The F1000 mode has the bottom latency. It’s not about “really feel”, I doubt most individuals may even inform the distinction between 150Hz and 500Hz, however sending your command even simply 1ms quicker means you could possibly react 1ms sooner which is essential when reacting to essential conditions like racing and would possibly allow you to to keep away from a crash.
  • D500, D250 – These are D mode, or DVDA (Deja Vu Variety Help), offers higher hyperlink connection in complicated interference surroundings by sending the identical information packet a number of occasions to cut back the prospect of information loss. D500 and D250 point out that the identical information packet is shipped twice and 4 occasions respectively. D mode retains your LQ excessive and forestall likelihood of jitter at the price of barely greater latency. Nice for racing. It really works on the FLRC mode (F1000) subsequently vary might be lower than regular mode
  • 333Hz Full, 100Hz Full – as much as 16 full decision (10-bit) channels in 100Hz and 333Hz packet charges. These are appropriate for fastened wings.

FLRC at 1000Hz is the most effective mode for racing, because it has the bottom latency. LoRa modes (regular mode) have the most effective vary. Slower replace charges have greater latency, however longer vary. FLRC D modes have decreased jitter, however greater latency than FLRC F modes. Observe that 500Hz or greater replace charges will not be out there in some radios, for instance the Tango 2 solely helps as much as 250Hz.

Telem Ratio

What’s telemetry?

Telemetry is a function generally out there in radio hyperlinks. It permits the receiver to ship information again to the radio, reminiscent of battery voltage, sign hyperlink high quality, RSSI, GPS coordinates and so forth.

Telemetry is enabled by default in ExpressLRS, it sends radio hyperlink associated information like RSSI and LQ again to the radio. If you happen to intent to make use of Telemetry to ship information about your drone again to the transmitter, reminiscent of battery voltage, it’s important to allow “Telemetry” function in Betaflight’s Obtain tab.

Telemetry Ratio in ExpressLRS settings is how typically telemetry information get despatched. A bigger quantity means slower telemetry replace, e.g. 1:8 means telemetry information is shipped each 8 frames, whereas 1:128 is each 128 frames (e.g. 1:8 is extra frequent replace than 1:128).

Extra frequent telemetry updates will improve latency to the management hyperlink, so you’ll be able to select to decrease telemetry fee and even disable it fully within the LUA script if you would like essentially the most constant management hyperlink. However I like to recommend having telemetry should you fly lengthy vary.

If you happen to get “Telemetry misplaced” warnings whereas your hyperlink high quality continues to be trying good, it could possibly be that your telemetry ratio is about too low. Strive growing Telem Ratio one step at a time till the “Telemetry Misplaced” warning stops.


What number of channels does ELRS help? 9 to16 channels relying on packet fee and swap mode.

For examples:

  • At 500Hz or 1000Hz, in Hybrid or Large swap mode, you get 12 channels.
  • At 100Hz or 333Hz, in Full Res 16CH, you get 16 channels.

The primary 4 channels are on your sticks – roll, pitch, throttle and yaw. These channels are 10-bit full decision and their instructions are despatched each transmission.

The remainder of the channels are AUX channels, usually used for switches on a radio.

The decision the channels are decided by the choice known as “Change Mode”. Larger decision channels end in greater latency.

The primary AUX channel, AUX1 (channel 5) is designed for use for the arming swap, and it’s all the time a 2-position channel (when OFF it sends 1000, when ON it sends 2000) regardless swap mode (aside from Full Res 16ch Charge/2).

Change Mode

Channel 1 to 4 are the management channels (roll, pitch, throttle and yaw) and are all the time 10-bit full decision. However for the remainder of the channels (AUX1-AUX8), these are usually used for switches and their decision is dependent upon your necessities.

The Change Mode setting controls how the channels AUX1-AUX8 (channel 5 to 12) are despatched to the receiver, there are two choices: Hybrid and Large.

With Hybrid swap mode, the AUX channels will solely be 2- or 3-position, that is best for much less latency. Large swap mode makes your channels 64 or 128 place which provides greater than sufficient decision for many issues we need to do.

For FPV drones, I usually advocate to make use of Large swap mode.

Gemini Mode (Antenna Mode)

Beginning with ExpressLRS 3.3, a brand new antenna mode often known as “Gemini” has been launched. This mode is designed to boost the steadiness of information transmission and reception by concurrently utilizing two totally different antennas and frequencies to transmit and obtain a single packet of information.

Be taught extra about how Gemini mode work on this article: https://oscarliang.com/expresslrs-gemini/

Nonetheless, it’s necessary to notice that utilizing Gemini mode could result in elevated battery consumption within the radio.

You want each transmitter and a receiver which can be appropriate with Gemini mode. Moreover, be certain that each gadgets are up to date to ExpressLRS model 3.3 or later. To activate Gemini mode, comply with these steps:

  1. Begin the ExpressLRS Lua script in your radio.
  2. Set the “Antenna Mode” to “Gemini”.
  3. Choose the receiver you’re binding with from the “Different System” menu.
  4. Set the “Rx Mode” to “Gemini”.

In case your receiver doesn’t help Gemini mode, make certain to change to Ant1/Ant2 modes to keep away from interference.

The primary transmitter module that helps Gemini is the BetaFPV SuperG Nano Transmitter Module: https://oscarliang.com/betafpv-superg-nano-transmitter-module/

Antenna Mode Choices

Transmitter Antenna Mode Description
ANT1/ANT2 Makes use of solely one of many two antennas for communication.
Change Alternates communication between two antennas.
Gemini Prompts Gemini mode for simultaneous use of two antennas on totally different frequencies.

Extra Receiver Settings

There are extra settings once you hook up with the receiver through WiFi (on the web page the place you flash RX firmware).

Radiomaster Er5a Er5c Expresslrs Elrs Pwm Receivers Wifi Flash Firmware Options Settings

First, energy on the receiver and wait till it goes into WiFi hotspot mode. It does it robotically after being powered for 60 seconds by default (LED flashing quickly when it’s in WiFi mode). Or it’s also possible to pressure the receiver to enter WiFi mode within the radio’s LUA script.

Now, hook up with the WiFi community (the WiFi password is: expresslrs). In your browser, go to

On this web page, scroll down and you will see the extra settings like Mannequin Match. For PWM receivers, additionally, you will have settings like PWM Output and Failsafe Positions for every channel, and the choice to invert the channel outputs. These setting will not be but out there within the LUA script.

Efficiency Enhancement Settings

In Betaflight, you must apply the acceptable RC_Link preset for the actual packat fee you’re utilizing. Failure to take action will end in issues with feedforward.

See my Betaflight Tuning information for more information.

Including Residence WiFi Community

It makes it a lot simpler to flash firmware once you setup “Residence WiFi Community” in ExpressLRS. While you put your ELRS transmitter module or receiver in WiFi mode, it can join robotically to your property WiFi community, then you definitely would have the ability to flash firmware on a browser out of your laptop. Straightforward!

To set it up, you first must flash your TX module and RX with “HOME_WIFI_SSID” and “HOME_WIFI_PASSWORD”. These are your property WiFi community title and password. Even if you’re already on the newest firmware, it’s important to re-flash to let your transmitter module and receiver know your community login for this to work.

Expresslrs Elrs Configurator V2.5 Home Wifi Network Ssid Password

As soon as that’s achieved, you’ll be able to activate WiFi mode. You are able to do this within the LUA script.

Expresslrs Elrs Lua Script V2 Wifi

Open ExpressLRS Configurator, and it’ll robotically detect your ELRS system. Click on on DNS (elrs_tx.native or elrs_rx.native), or the IP deal with (192.168.0.XXX), if it doesn’t work simply attempt the opposite, one among them ought to work.

This can deliver you to the web page to add the firmware, similar as flashing utilizing the WiFi methodology we lined earlier than.

Expresslrs Elrs Configurator V2.5 Home Wifi Network Dns Ip

Easy methods to Use Mannequin Match

What’s Mannequin Match?

Mannequin Match is a quantity you’ll be able to assign to a receiver, this lets you use a mannequin profile on the radio to solely management a selected receiver.

If you happen to usually use one mannequin profile to regulate all your fashions (as a result of they’re all utilizing the identical sort of radio receiver and setup the identical manner) as an alternative of getting particular person profile for every mannequin, you most likely don’t need to use “mannequin match”. However mannequin match is beneficial for fashions the requires trims, for instance for planes and wings.

To make use of mannequin match in ExpressLRS, go to Mannequin Setup in your radio, scroll right down to Inner RF (or Exterior RF if you’re utilizing an exterior ELRS module). In Receiver, set it to a singular Mannequin ID (any quantity between 0 and 63, on this instance, I’ll use 2).

Expresslrs Model Match Radio Model Setup Receiver Id Internal External Rf

Put your receiver in WiFi mode, go to the webpage configuration, Mannequin, and allow Mannequin Match. Set Mannequin ID to the identical quantity you entered in Mannequin Setup in your radio.

Expresslrs Model Match Webpage Configure Receiver Enable Id Save

Go to ExpressLRS LUA script, and allow Mannequin Match.

Expresslrs Model Match Receiver Lua Script On

Now your receiver can solely speak to this explicit mannequin profile with Receiver ID 2. That’s it.

SPI Receiver

When you’ve got a SPI receiver, or a receiver that doesn’t have WiFi functionality, you’ll be able to set Mannequin ID in CLI. You possibly can’t set the ID by simply rebinding whereas mannequin match is on, so i needed to go to betaflight CLI and enter:

get expresslrs_model_id

to point out me its ID and that i needed to:

set expresslrs_model_id = "your ID quantity"

Easy methods to Output SBUS

ExpressLRS receivers by default output CRSF sign, which requires 2 wire connections (TX and RX). Nonetheless you could possibly configure your receiver to output SBUS which solely wants 1 wire, comply with tutorial right here: https://oscarliang.com/how-to-output-sbus-from-an-expresslrs-receiver/

SBUS is an previous and sluggish protocol and doesn’t help telemetry, subsequently I wouldn’t advocate it except it’s the one protocol you need to use along with your flight controller.

Initialization Charge

While you swap on the receiver, there could also be a delay of some seconds whereas the receiver tries totally different packet charges till a match is discovered with the transmitter. The delay will rely on the packet fee – the slower the speed, the larger the delay.

If you happen to all the time transmit on the similar packet fee, you’ll be able to cut back the delay by doing this: Open LUA script, choose Different Units, choose your receiver and set Initialization Charge to the speed you all the time use. After that, connection might be nearly instantaneous once you energy on the transmitter and receiver.

EdgeTX Telemetry Low/Vital Alarms

EdgeTX and OpenTX use hyperlink high quality (RQly telemetry) as an alternative of RSSI for the low/essential alerts. Beneficial thresholds are 50% for low alarms and 20% for essential alarms. You possibly can enter these values within the Telemetry web page of your radio.

Configurations For Fastened Wings

These settings could be best for fastened wings with out a flight controller or stablizer (if the receiver is related on to servos and ESC).

Utilizing Full Modes

In Packet Charge, use both 100Hz Full or 333Hz Full.

These modes present full 10-bit decision (1024 positions) for all channels which is essential for exact management if you wish to drive servos and ESC straight from a PWM receiver. Between 100Hz and 333Hz full modes, there’s a commerce off between vary and latency. 100Hz is best for vary whereas 333Hz is best for latency.

You then additionally need to resolve which swap mode you need to use, the choices are:

  • 8 Channel (1 to 4 and 6 to 9 are despatched 10bit full fee).
  • 16 Channel (all channels despatched 10 bit however half fee).
  • 12 Channel combined (1 to 4 are 10 bit full fee, 6 to 13 are 10bit however half fee).

For many fixed-wing fashions, 333Hz Full with 8-channel swap mode provides a great stability, making certain every channel is up to date with every transmission for the bottom latency and highest decision. The 16-channel possibility may be tempting but it surely does introduce extra delay as channels are despatched alternately (half fee).

Observe: The entire swap modes use CH5 for arming, which has solely two positions. Channel 5 have to be excessive for the system to transition from standby to energetic mode. This requirement might be seamlessly built-in into fixed-wing configurations through the use of a throttle lower swap to regulate each the throttle and Channel 5’s state. This method not solely simplifies setup but in addition ensures your mannequin is able to fly when you find yourself, with out losing a channel on the receiver. I’ve a tutorial on setup a throttle lower swap right here: https://oscarliang.com/setup-arm-switch-for-wing-no-fc/

Remap PWM Receiver Outputs

Fashionable PWM receivers supply the flexibleness to remap output channels. Given the present requirement of holding Channel 5 excessive throughout flight, it’s sensible to take away Channel 5 from the output mapping in a hard and fast wing with out an FC, making certain no output is wasted.

Setup Failsafe

You possibly can setup failsafe within the WebUI by assigning a predefined worth to every channel when the radio hyperlink is misplaced. It’s necessary to make sure the throttle is about to low in failsafe so your mannequin will glide to a protected touchdown.


What’s ExpressLRS TX BackPack?

The TX Backpack is an non-obligatory function throughout the ExpressLRS ecosystem. It allows wi-fi management of FPV-related gadgets straight out of your radio transmitter. As an illustration, you’ll be able to conveniently alter the channel of your analog FPV goggles utilizing the radio management.

To make the most of TX Backpack, each the ExpressLRS transmitter and the system being managed have to be geared up with an ESP8285 chip. This chip, integral to the performance, is what we seek advice from because the “TX Backpack.”

Ideas for Lengthy Vary

  • Set the very best legally attainable transmit energy
  • Choose a decrease replace fee, e.g. 50Hz can have higher vary than 500Hz on the similar energy
  • Select a real range receiver with PA and LNA functionality
  • Use high-quality antennas in your receiver, ideally half-wave dipole (T-shaped) ones. Keep away from utilizing ceramic antenna for lengthy vary
  • Optimize antennas placement as defined right here: https://oscarliang.com/antenna-positioning/
  • Get the next acquire antenna on your transmitter
  • Think about using 900Mhz as an alternative of two.4Ghz for final lengthy vary. (2.4GHz continues to be very succesful although)
  • For extra recommendations on lengthy vary take a look at my tutorial: https://oscarliang.com/long-range-fpv-flying-mini-quad/

Unable to make use of F1000 packet fee or prompts “Baud fee is simply too low”

F1000 requires a baud fee greater than 400K, and the radio transmitter’s baud fee is 400K by default.

First replace the baud fee (higher than 400K) setting within the {Hardware} in Radio Setup menu, then restart the radio transmitter to make sure the baud fee setting has been utilized. Then change the Packet fee.

In case your radio don’t help greater baudrate then your can’t run F1000 mode.

When the F1000 is turned on, packet fee is lower than 1000

This could possibly be resulting from outdated EdgeTX model. You could replace to 2.8.0 or newer.

Identical radio controlling a number of receivers concurrently

What occurs should you energy up a number of drones which can be all sure to the identical radio?

You possibly can management all of those drones on the similar time, however telemetry gained’t work correctly as all of them attempting to ship telemetry again to the radio and they’ll intrude with one another.

To keep away from this from taking place, you could possibly use mannequin match (every receiver would require an distinctive ID and a separate mannequin profile). See “Easy methods to Use Mannequin Match” on this information for directions set it up.

Why Does My Radio Maintain Saying “Telemetry Misplaced”?

Often, you would possibly get a warning out of your radio saying “Telemetry misplaced,” but nonetheless retain full management and a superbly advantageous video hyperlink. So, what’s the explanation behind this?

Your ExpressLRS radio hyperlink is bi-directional, that means your receiver just isn’t solely receiving indicators but in addition transmitting them. Whereas some transmitters in radios can output as much as 1000mW, receivers usually have a a lot decrease energy output, often round 25mW. Some newer receivers would possibly attain as much as 100mW, however that is nonetheless significantly decrease than the transmitter.

A normal rule of thumb is that 4 occasions the transmission energy doubles the vary. In line with this, 1000mW would have 2.6 occasions the vary of 25mW. To study extra about FPV vary, take a look at this text: https://oscarliang.com/calculate-fpv-range

On condition that the receiver has a a lot shorter vary than the transmitter, when your transmitter isn’t receiving information from the receiver, you’ll hear the fixed “telemetry misplaced” warning. It’s often not a difficulty so long as you continue to preserve full management of the plane. It merely signifies that you just’re not receiving telemetry information, which isn’t important for sustaining a management hyperlink. Nonetheless, remember that your transmitter depends on telemetry for sure options, reminiscent of dynamic energy. If telemetry is weak, your transmitter would possibly unnecessarily use most energy, though much less energy would possibly suffice for reaching the receiver.

If you wish to get rid of this annoying warning, take into account the next strategies:

  • Improve to a receiver with greater telemetry energy (at present, the very best is 100mW).
  • Flip off the telemetry warning in your radio’s settings.
  • Set Telemetry Ratio to plain, or a decrease ratio would possibly assist

Lua Script simply retains Loading, Can’t Enter

When your run the ExpressLRS LUA script and “loading…” seems on the display and nothing else occurs, be sure you have enabled Inner RF (or Exterior RF if you’re utilizing an exterior module).

Be sure to have the newest model, if doubtful, flash your module once more and obtain the newest LUA script.

The baud fee of the radio transmitter is about beneath 400K in radio setup, and it needs to be adjusted to the next baudrate worth. If there isn’t a possibility to switch the baud fee, be certain that EdgeTX is at model V2.7.0 or newer.

“Dangerous Dimension Given” Error

V2 and V3 handles partition in another way (as they moved in direction of unified goal), so once you flash V3 firmware to your module with V2 firmware, the file dimension get tousled and also you get “Dangerous Dimension Given” error.

The repair is to obtain “repartitioner.bin“, on WiFi web page, add this file as an alternative of firmware file. It’s going to say goal mismatch, choose flash anyway.

Now flash the V3 firmware once more, it ought to undergo this time.

Receiver Replace Warning: ”Not sufficient information uploaded!“

If you happen to attempt to flash firmware of a distinct goal, and pressure replace, you’ll get this error “Not sufficient information uploaded”.

It’s a bug/function in ELRS 2.5 that forestalls goal altering. If you happen to nonetheless need to go forward and flash a distinct goal, you first must revert the RX firmware again to 2.0 (on the unique goal), then flash the totally different goal you want.

LUA script solely exhibits “Connecting…”

That’s a sign of the ExpressLRS TX module just isn’t speaking to the LUA script

Doable causes of the issue:

  • TX Module is put in, or is put in incorrectly (pins within the module bay don’t make correct contact or damaged)
  • Perhaps the TX module is in WiFi replace mode, restart the radio and check out once more
  • Be sure to have set RF protocol to CRSF
  • In case you are operating OpenTX, make certain the model just isn’t too previous (it must be 2.3.12 or after)

Easy methods to Set up Cooling Fan on Happymodel TX Module

There isn’t any fan plug for the Happymodel 2.4GHZ TX module, it’s essential to solder it straight. I discovered 3.3V and GND at this capacitor. Be sure to affirm voltage with a multimeter earlier than connecting to keep away from damaging the board.

Happymodel Expresslrs Elrs 2.4ghz Tx Module 3.3v Fan Solder I’m utilizing a 20x20x6mm 5v fan which inserts completely of their new module cowl. The fan might be purchased on Amazon (affiliate hyperlink): https://amzn.to/3ixZpE0. The fan ought to act as an exhaust and take the new air out, not blowing onto the PCB to keep away from mud build up contained in the module. Present draw is sort of low in order that shouldn’t be a difficulty. At 5V, 0.05A.

Happymodel Elrs 2.4ghz Tx Module Fan Solder

Inconsistent Packet Charge – CRSFShot Not Working

Within the ELRS lua script high bar, there may be an indicator (e.g. 0:200) which tells you what number of packets per second it’s getting from the radio. You should use it to substantiate the consistency of the RC hyperlink.

Expresslrs Elrs Lua Script V2 Interface App

Ideally it ought to all the time present a secure quantity that’s the similar because the packet fee you choose. For instance: 0:50, 0:150, 0:250, 0:500.

If it exhibits an inconsistent quantity like 0:63, or is caught at 0:250 at each packet fee you choose, then your radio doesn’t have CRSFShot working correctly.

The most recent official launch of OpenTX (2.3.12 or newer) already consists of CRSFShot, so double verify in case your OpenTX model is outdated.

Utilizing ExpressLRS Brand as Mannequin Picture

I made a brand you need to use as mannequin picture within the TX16S/T16. You possibly can learn to use it right here.

Picture obtain: google drive.

Set up USB to UART Driver

You would possibly or won’t want to put in this driver in your PC if you wish to replace your TX through UART: https://www.silabs.com/builders/usb-to-uart-bridge-vcp-drivers

Taranis QX7

For Taranis QX7 customers, if you’re operating OpenTX, you’ll must carry out this mod to be able to run 400k baud fee in your radio. It’s not wanted, however it is suggested if you wish to get essentially the most out of ELRS: https://www.youtube.com/watch?v=mHfQe05XJn8&ab_channel=edrone

If you happen to run EdgeTX you gained’t want to do that mod because the bug has been addressed in software program.

Edit Historical past

  • Jun 2021 – Up to date information: OpenTX 2.3.12 has been launched, now not must flash nightly
  • Jul 2021 – Up to date: ExpressLRS 1.0 official launch
  • Aug 2021 – Added information for BetaFPV ELRS Nano TX and RX
  • Nov 2021 – Up to date product checklist
  • Feb 2022 – Up to date the entire TX, RX and antenna choices at present out there available on the market
  • Could 2022 – Up to date directions for model 2.5, added information about including house community, up to date screenshot of LUA script (V2)
  • Oct 2022 – Up to date information for ELRS V3 launch, added PWM receiver merchandise
  • Mar 2023 – Added information about mannequin match, added extra FAQ, up to date product hyperlinks
  • Mar 2024 – ELRS 3.3 replace, new merchandise.

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