ELRC Remote Controller Preparation

I. ExpressLRS Module

1.1 External Module

Insert or connect the external ExpressLRS transmitter module to the radio module holder, ensuring no pins are bent or missing. The external ExpressLRS module requires three pins to operate: VCC/VBAT, GND, and S.Port/Data/Signal.
Micro External Holder Pins:

Nano External Holder Pin Layout:

Please ensure your RC transmitter is indeed equipped with a built-in ExpressLRS module. The following handheld transmitters are available in ELRS (ExpressLRS) and 4-in-1 versions, with some models also offering a CC2500 version.
⚠️ Only the ELRS version can be used with ExpressLRS, other versions cannot use ExpressLRS due to hardware incompatibility.
Compatible Transmitter Version Identification for ExpressLRS:

• RadioMaster TX16S Mark II（ELRS, 4-in-1, CC2500） ELRS version: The packaging box has a ELRS sticker.
• RadioMaster TX12 Mark II（ELRS, 4-in-1, CC2500） ELRS version: The packaging box has a ELRS sticker, and there is also a ELRS sticker inside the JR module bay.
• RadioMaster Zorro（ELRS, 4-in-1, CC2500） ELRS version: The packaging box has a ELRS sticker.
• RadioMaster Boxer（ELRS, 4-in-1, CC2500） ELRS version: The packaging box has a ELRS sticker, and there is also a ELRS sticker inside the JR module 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） ELRS version: The barcode sticker on the bottom of the packaging box can be used to distinguish between the ELRS version or CC2500 version.
  

II. Transmitter System

ExpressLRS requires CRSFShot or Mixer Sync to ensure full support for high packet rates.
You should use OpenTX 2.3.12 or later, or EdgeTX 2.4.0 or later, which versions support CRSFShot/Mixer Sync.
How to Determine Your Transmitter's System Version:

1. Press the SYS button on the transmitter

• Older transmitters or those with only one menu key require a long press of the Menu key to access the System Menu.
• Refer to your Radio user manual for instructions on how to access the System Menu.

2. Press the PAGE key until you reach the Version Page.
   
   ExpressLRS strongly recommends using EdgeTX for the best experience and compatibility.
   EdgeTX introduces some new features that both new and old transmitters can benefit from, such as:

• One Bit Sample Mode: Primarily suitable for older FrSky transmitters (such as X9D and QX7).
• Mega Bauds: Supports baud rates over 400K, enhancing communication efficiency.

Important

If you are using an older version, please update your transmitter first. If you don't know how to do this, please refer to this article: https://docs.corewing.com/plane/other/edgetx/buddy-fw-update.html

Important

If you are using the OpenTX system and want to update to the EdgeTX system, please refer to this article: https://docs.corewing.com/plane/other/edgetx/buddy-update-opentx.html

3. Single Selection Settings

3.1 Serial Baud Rate

The baud rate refers to the communication speed between the transmitter module and the RC transmitter in this case, measured in bps (bits per second).
Common baud rates include:

• 115200bps (sometimes marked as 115K)
• 400000bps (sometimes marked as 400K)
  Effects of Baud Rate:
• Higher baud rate means faster communication speed between the module and RC transmitter, thereby reducing end-to-end system latency.
• Hardware limitations: Not all RC transmitters or transmitter modules support higher baud rates; support depends on hardware capabilities.
  Based on your RC transmitter firmware (such as EdgeTX or OpenTX), you can adjust the baud rate settings to better match your equipment.

3.2 How to Access the RC Transmitter's Baud Rate Settings

3.2.1 EdgeTX Internal TX

1. Press the SYS button.
2. Press the PAGE key until you reach the Hardware page.
3. Scroll down until you reach the Internal RF settings.
4. Press the Enter key.
5. Use the scroll wheel to change Baudrate and select the one to use.
6. Press the Enter key once to apply the changes.
7. Restart the RC transmitter (turn it off and then on again).
   

3.2.2 EdgeTX External TX

1. Press the MDL button.
2. Press the PAGE key until you reach the Model Setup page.
3. Scroll down until you reach the External RF settings.
4. Select the Baudrate settings.
5. Press the Enter key.
6. Use the scroll wheel to change Baudrate and select the one to use.
7. Press the Enter key to make the changes.
8. Restart the RC transmitter (turn it off and then on again).
   

3.2.3 OpenTX System

1. Press the SYS button.
2. Press the PAGE key until you reach the Hardware page.
3. Scroll down until you reach the Baudrate settings.
4. Press the Enter key.
5. Use the scroll wheel to change Baudrate and select the one to use.
6. Press the Enter key to make the changes.
7. Restart the RC transmitter (turn it off and then on again).
   

3.3 Recommended Baud Rates

The minimum required baud rate depends on the highest packet rate you plan to run. The baud rate should be set to:

• 400K (400000bps): Suitable for 250Hz and lower packet rates. This setting should be suitable for most Radios and TX Modules.
• 921k (921000bps): Suitable for 500Hz and lower packet rates.
• 1.87M (1870000bps): Suitable for packet rates up to F1000.
  However, there are some exceptions:
• Without a Crossfire Mod, FrSky Taranis QX7 ACCST, Horus X12S, and Horus X10S cannot reliably run at 400K baud rate.
• It has been found that FrSky Taranis X9D is quite particular even with the default 400K baud rate and will benefit from One Bit sampling mode settings and hardware Mod.
  On other transmitters, you can set the baud rate higher than 400K, but this largely depends on the TX module you will be using with it.
  Maximum Usable Baud Rates
  
  
  
  The maximum baud rate for external modules still depends on the hardware capabilities of the transmitter. As mentioned above, older transmitters (such as QX7 and X9D(+)) require hardware modifications and software adjustments to operate stably at higher baud rates, such as enabling One Bit sampling mode.
  Therefore, we recommend that the baud rate for these transmitters should not exceed 400K. If a higher baud rate is set, it may cause instability, and the risk is borne by the user.
  Meanwhile, newer EdgeTX transmitters can easily support higher baud rates without any modifications, so it is recommended to use the highest available baud rate when possible to achieve lower latency and better performance.
  If your TX module is not on the list, it just means that the maintainer's updates are somewhat delayed; new TX modules being released now are basically based on ESP.
  If your TX module has WiFi or Bluetooth connectivity, then it is ESP-based and should theoretically be able to support 5.25M baud rate (depending on your transmitter).

3.4 ADC Filter

In OpenTX, the ADC filter is enabled by default, but it is known to affect RC Command data, which may cause "jagged" RC command responses in Blackbox Logs.
This phenomenon is caused by consecutive RC data packets having the same command values, which are then "smoothed" by the ADC filter.
Therefore, we recommend disabling the ADC filter in OpenTX/EdgeTX to ensure the accuracy and smoothness of RC commands.
How to Check and Change This Setting:

1. Press the SYS button.
2. Press the PAGE key until you reach the hardware HARDWARE page.
3. Scroll down until you reach the ADC Filter settings.
4. Press the Enter key to toggle it to On or Off.
   

4. Model Setup

4.1 RF Protocol

If you are using an external ExpressLRS module, please ensure the internal RF module is Off.
If your radio has an internal ExpressLRS module and you want to use it instead of the external module, set the external RF module to OFF, then set the internal RF module to CRSF protocol.
ExpressLRS uses the CRSF serial protocol for communication between the transmitter and TX module. Follow these steps to set it up on the currently selected Model:

4.1.1 Using an External ExpressLRS Module

1. Press the MDL button.
2. Hold the PAGE key until you reach the Model Setup page.
3. Scroll down until you reach the Internal RF setting. Set this to Off
4. Scroll down until you reach the External RF setting.
5. Set the Mode to CRSF
6. (Optional) Set the Receiver ID to a unique number.
7. Press the RTN key or exit the Model menu.
   Monochrome screen settings:
   
   Color screen settings:
   

4.1.2 Using an Internal ExpressLRS Module

1. Press the MDL button.
2. Press the PAGE key until you reach the Model Setup page.
3. Scroll down until you reach the Internal RF setting.
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 setting, set this to Off.
7. Press the RTN key or exit the Model menu.
   Monochrome screen settings:
   
   Color screen settings:
   

4.2 Switches and Aux Channels

By default, newly created models do not have any Aux Channels configured. Aux channels start from Ch5, while the first 4 channels (Ch1-Ch4) are typically assigned to stick inputs.
Therefore, if nothing happens to the Modes in Betaflight or INAV when you toggle switches on your transmitter, this is likely one of the main reasons.
How to solve this issue:

1. Press the MDL button.
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.
5. (Optional) You can name this channel in a way that reminds you of its purpose.
   
6. Select Source and press Enter.
7. Activate the Switch you want to use for this channel.
   For example, for CH5 (typically used as the arming switch), you need to select a 2-position switch to control it.
8. Press Enter again to set the switch.
9. Press the RTN key once to exit the Channel Mix editor.
10. Repeat steps 3-9 until you have configured all the switches you think you need.
    ——This article is referenced from ExpressLRS Getting Started: https://www.expresslrs.org/quick-start/transmitters/tx-prep/#switches-and-aux-channels**