Radio Preparation

External ExpressLRS Modules¶

Insert or attach your External ExpressLRS Transmitter Module into your Radio module bay, making sure no pins are bent or missing. External ExpressLRS Modules require three (3) pins to work: VCC/VBAT, GND and S.Port/Data/Signal.

Internal ExpressLRS Modules¶

Make sure you do have an Internal ExpressLRS Module on your shiny new radio. The following handsets come in both ELRS (ExpressLRS) or 4-in-1 variants; with some coming in with a third (CC2500). Only the ELRS variant works with ExpressLRS. The others will not work as they have a different Hardware incompatible with ExpressLRS.

• RadioMaster TX16S Mark II (ELRS, 4-in-1 CC2500) - ExpressLRS variant will have an ELRS sticker on the box.
• RadioMaster TX12 Mark II (ELRS, 4-in-1, CC2500) - ExpressLRS variant will have an ELRS sticker on the box and a blue ELRS sticker in the JR module bay.
• RadioMaster Zorro (ELRS, 4-in-1, CC2500) - ExpressLRS variant will have an ELRS sticker on the box.
• RadioMaster Boxer (ELRS, 4-in-1, CC2500) - ExpressLRS variant will have an ELRS sticker on the box and a blue ELRS sticker inside the battery bay.
• RadioMaster Pocket (ELRS, CC2500) - ExpressLRS variant will have an ELRS sticker on the box and a blue ELRS sticker inside the radio.
• RadioMaster MT12 (ELRS, 4-in-1) - ExpressLRS variant will have an ELRS sticker on the box and a blue ELRS sticker within the battery bay.
• Jumper T-Lite V2 (ELRS, 4-in-1, CC2500)
• Jumper T-Pro V1/V2 (ELRS, 4-in-1)
• BetaFPV Lite Radio 3 Pro (ELRS, CC2500) - A sticker with the barcode at the bottom of the box should tell you it's an ELRS variant or the CC2500 variant.

FlySky is also now offering handsets with an ExpressLRS-compatible internal module like the PA01. Early batches of the radio comes with AFHDS3 firmware and can be converted to ExpressLRS via FlySky's online tool under the RF Firmware Tab or by just flashing via the ExpressLRS Configurator or Webflasher.

Radio Operating System¶

ExpressLRS requires CRSFShot or Mixer Sync to ensure full support for high packet rates. You should have OpenTX 2.3.12 or newer, or EdgeTX 2.4.0 or newer; These versions have full CRSFShot/Mixer Sync support.

To determine your Radio Operating System Version, load the Version page from the System Menu of your Radio:

1. Press the SYS Key.
   • Older Radios or those with only one Menu Key will need to long-press the Menu Key to access the System Menu.
   • Consult your Radio User's Manual on how to access the System Menu.
2. Press PAGE Key until you reach the Version Page.

If you have an older version, please first update your Radio OS to at least the mentioned versions. Please consult your Radio Operating System Updating Procedure if you don't know how.

ExpressLRS highly recommends EdgeTX for the best experience and compatibility. EdgeTX has introduced options that old and new Radio handsets will benefit from, like One Bit Sample Mode (mainly for old FrSky Radios like the X9D and the QX7) and Mega Bauds (baud rates higher than 400K).

Check this page for the EdgeTX installation instructions if you're coming in from OpenTX or updating from an earlier EdgeTX version.

Radio Settings¶

Serial Baud Rate¶

The Baud Rate is the speed to which (in this instance) the Transmitter module and the Radio Handset communicate. It is measured in bits per second. Common baud rates include 115200bps (sometimes shown as 115K) and 400000bps (sometimes shown as 400K).

A faster or higher baud rate means that the module and radio can talk much faster, further lowering the end-to-end latency of the system. However, not all radio handsets or transmitter modules are capable of higher baud rates as this is highly dependent on the hardware.

Depending on the firmware that is running on your radio handset, you can change the baud rate setting to better suit your setup.

To get to the baud rate setting on your radio:

EdgeTX, Internal ModuleEdgeTX, External ModuleOpenTX

1. Press the SYS Key.
   • Older Radios or those with only one Menu Key will need to long-press the Menu Key to access the System Menu.
   • Consult your Radio User's Manual on how to get to the System Menu.
2. Press the PAGE Key until you get to the Hardware page.
3. Scroll down until you reach the Baudrate setting.
4. Press the Enter Key.
5. Use the Scroll wheel to change and select the Baudrate you want to use.
6. Press Enter Key once to apply the changes.
7. Reboot the Radio (turn it Off, then turn it On again).

1. Press the MDL Key.
   • Older Radios or those with only one Menu Key will need to short-press the Menu Key to access the Model Menu.
   • Consult your Radio User's Manual on how to get to the Model Menu.
2. Press the PAGE Key until you get to the Model Setup page. On Colored Screen Radios, this should not be needed.
3. Scroll down until you reach the External RF settings.
4. Select the Baudrate setting.
5. Press the Enter Key.
6. Use the Scroll wheel to change and select the Baudrate you want to use.
7. Press Enter Key once to apply the changes.
8. Reboot the Radio (turn it Off, then turn it On again).

1. Press the SYS Key.
   • Older Radios or those with only one Menu Key will need to long-press the Menu Key to access the System Menu.
   • Consult your Radio User's Manual on how to get to the System Menu.
2. Press the PAGE Key until you get to the Hardware page.
3. Scroll down until you reach the Baudrate setting.
   • If you don't see this setting, that means your radio doesn't support changing the baud rate in this firmware and is locked at 400000.
4. Press the Enter Key.
5. Use the Scroll wheel to change and select the Baudrate you want to use.
6. Press Enter Key once to apply the changes.
7. Reboot the Radio (turn it Off, then turn it On again).

Recommended Baud Rates¶

The minimal required Baudrate depends on the highest Packet Rate you intend to run. The Baudrate should be set to:

• 400K (400000bps): for Packet Rates of 250Hz and lower. This setting should work on most Radios and TX Modules.
• 921k (921000bps): for Packet Rates of 500Hz and lower.
• 1.87M (1870000bps): for Packet Rates F1000 and lower.

However, there are some exceptions:

• The FrSky Taranis QX7 ACCST, Horus X12S and Horus X10S cannot reliably run 400K baud rate without the Crossfire Mod.

• The FrSky Taranis X9D has proven to be finicky even with the default 400K baud rate and will benefit from the One Bit Sample Mode setting and a Hardware Mod. See Troubleshooting the X9D for more details.

On other Radios, you can set the Baudrate higher than 400K but will highly depend on what TX Module you will use with it.

Max Usable Baud Rates¶

ADC Filter¶

The ADC filter is enabled by default in OpenTX and is known to cause issues with RC Command data. This can result in "jagged" RC command responses in black box logs, caused by sequential RC packets that have the same command value (which were "smoothed" by the ADC filter). We recommend turning the ADC filter OFF in OpenTX/EdgeTX for applications involving a flight controller that can smooth out or filter the channel data (like Betaflight, etc.).

To check and change this setting, follow these steps:

1. Press SYS Key.
   • Older Radios or those with only one Menu Key will need to long-press the Menu Key to access the System Menu.
   • Consult your Radio User's Manual on how to get to the System Menu.
2. Press the PAGE Key until you reach the Hardware Page.
3. Scroll down until you reach the ADC Filter setting.
4. Press Enter Key to toggle it On or Off.

Model Setup¶

RF Protocol¶

ExpressLRS uses the CRSF serial protocol to communicate between the transmitter and the TX module. Follow the following procedure to set it up on the currently selected Model:

External ExpressLRS ModulesInternal ExpressLRS Modules

1. Press the MDL Key.
   • Older Radios or those with only one Menu Key will need to short-press the Menu Key to access the Model Menu.
   • Consult your Radio User's Manual on how to get to the Model Menu.
2. Press the PAGE Key until you reach the Model Setup Page. On Colored Screen Radios, this should not be needed.
3. Scroll down until you reach the Internal RF settings. Set this to Off.
4. Scroll down until you reach the External RF settings.
5. Set the Mode to CRSF.
   • You can also change the baud rate setting at this point.
6. (Optional) Set the Receiver ID to a Unique Number.
7. Press the RTN Key or Exit the Model Menu

1. Press the MDL Key.
   • Older Radios or those with only one Menu Key will need to short-press the Menu Key to access the Model Menu.
   • Consult your Radio User's Manual on how to get to the Model Menu.
2. Press the PAGE Key until you reach the Model Setup Page. On Colored Screen Radios, this should not be needed.
3. Scroll down until you reach the Internal RF settings.
4. Set the Mode to CRSF.
5. (Optional) Set the Receiver ID to a Unique Number.
6. Scroll down until you reach the External RF settings. Set this to Off.
7. Press the RTN Key or Exit the Model Menu

No CRSF Mode Option? (click/tap to expand)

If for some reason, you cannot find the CRSF Protocol under the Internal RF Modes, set the Internal Module Type to CRSF via your Radio's System Menu -> Hardware page.

1. Press the SYS Key.
   • Radios without a dedicated SYS Key will need to long-press the Menu Key to access the System Menu.
   • Consult your Radio User's Manual on how to get to the System Menu.
2. Press the PAGE Key until you get to the Hardware page.
3. Scroll down until you reach the Internal RF settings.
4. Set the Type to CRSF.
   • You can also set the Baudrate at this point.
5. Press the RTN Key or Exit the Hardware Menu, and go back into setting your Internal RF module.

Version 4.0 Arming Options¶

Starting with ExpressLRS v4.0.0 an additional Arming method is introduced.

The traditional Arming method, using Channel 5 (Aux1) driven by EdgeTX Mixer's Channel 5 is the default and is still encouraged to be used by majority of FPV pilots using Betaflight, INAV or Ardupilot (and their respective derivatives like Emuflight, Rotorflight, etc.) more so when using non-Full Res modes. This is because you are still required to have a mode for arming using an Aux channel. This will now be called Arm using CH5 and is set by EdgeTX (2.11 or newer) as default.

See the next section on how to configure your Channel Mixes.

The alternative Arming method, Arm using switch is more suited to users who aren't familiar with drone-side arming concept, or primarily those using PWM receivers. Arm using Switch is performed by user selected sources, e.g. physical or logical switches, anything EdgeTX offers as a source. It works in all packet rates and switch modes, with varying channel reactions, explained below.

When in Full Res modes, Channel 5 will behave as any of the other full proportional channels. This means:

• No need to remap Output 5 with other channel input sources.
• No need to skip Output 5 on your PWM receivers if you don't know how to remap outputs.
• SBUS-dependent Stabilizer gain control requiring Channel 5 will work now.
• Flight Modes requiring Channel 5 will also work.

When not in Full Res mode, Channel 5 will behave as a 2-position switch, but it will not use the configured Mix for Channel 5 and instead use the configured arming switch as the Channel source.

Arm using Switch can be enabled in the EdgeTX Internal/External RF Model Setup menu by changing “Arm using” to “Switch”.

How to set up Arming Mode Switch:¶

1. Press the MDL Key.
   • Older Radios or those with only one Menu Key will need to short-press the Menu Key to access the Model Menu.
   • Consult your Radio User's Manual on how to get to the Model Menu.
2. Press the PAGE Key until you reach the Model Setup Page.
   • On radios with Colored screens, this should be the first page when you activate the Model Menu.
   • On radios with Monochrome screens, this should be the second page upon activating the Model Menu.
3. Scroll down until you reach the Internal or External RF settings, depending on which module you want to use for this model.
   • Color screen radios provide separate pages for these.
   • On Monochrome screens, the options are all in one page.

4. Short-press the scroll-wheel button or press the Enter Key and change the setting to "Switch". This option will not show up for External RF unless an External ExpressLRS Module is being detected by the handset.

   

   

5. Press the Enter Key to apply your selection.

   

6. Select the next option to set your arming switch.

7. Press the Enter Key and use the scroll-wheel to set your new arming switch. It can be any switch on the radio, a Logical Switch or any source. You can also flick the physical switch on the radio to set it.

   

8. Press the Enter Key once more to set the switch.

9. Press RTN Key once you're done with the rest of your changes.

Switches and Aux Channels¶

By default, a fresh model does not have any Aux Channels configured (Aux channels start from Ch5, with the first 4 Channels assigned to your joysticks/gimbals). If moving any of the switches in your radio doesn't affect your Modes in Betaflight or INAV, this is one of the main reasons. So let's get this sorted out!

1. Press the MDL Key.
   • Older Radios or those with only one Menu Key will need to short-press the Menu Key to access the Model Menu.
   • Consult your Radio User's Manual on how to get to the Model Menu.
2. Press the PAGE Key until you reach the Mixes Page.
3. Scroll down and select the Channel you want to configure.
4. Long press Enter and select Edit and press Enter once more.
5. (Optional) You can name this channel however you want to remind you of its purpose.
6. Select Source. Press the Enter Key.
7. Activate or flick the Switch you'd want to use for this channel.
   • An example would be for CH5, which can be your Arming switch, you'd want to choose a 2-position switch.
8. Press the Enter Key once more to set the switch.
9. Press RTN Key once to exit the Channel Mix editor.
10. Repeat steps 3-9 until you have configured all the switches you think you will need.

Mono-Screen RadioColored-Screen Radio

Channel Mixing¶

This is important for those using PWM Receivers, and isn't using flight controllers. You would want to configure at least a basic channel mix for your application. Consult the EdgeTX documentation for a few simple mixes or utilize their Model Wizard for basic setup.

Once you have your PWM Receiver sync'd with your TX module or Radio, revisit your mix to confirm your control surfaces work as they should and adjust your mix as necessary, BEFORE attempting your first flight.