How to update Happymodel series receivers firmware

If you flash directly to version 3.x, and encounter a "Not Enough Space" popup during WiFi flashing, first flash the receiver to version 2.5.2, then flash to version 3.x.

If the receiver firmware is already version 3.x, and you still encounter a "Not Enough Space" error when flashing via WiFi, ensure you have selected the correct flashing method in the configurator (in this case, via WiFi). Please follow the steps listed below.

You can also update directly to version 3.x via Passthrough or UART.

I. Connecting the Receiver

It should be noted that the RX pin on the receiver should be soldered to the TX pad on the flight controller board, and the TX pin on the receiver should be soldered to the RX pad on the flight controller board.

Happymodel EP:

Happymodel PP:

Happymodel ES900RX：

II. Configuring the Flight Controller

To properly configure your flight controller, the following settings apply to INAV, Betaflight, and other flight controller software.

If any of these settings are incorrect, the following steps will not proceed smoothly, and you may encounter issues later.

1. After completing the flight controller software configuration, close its configurator and unplug/replug the flight controller's USB cable, or disconnect and reconnect it from the computer to refresh the connection and ensure the port is not occupied.
2. If these settings are incorrect, subsequent operations, especially updating via the Passthrough method or the receiver not working properly, will be affected.

III. Updating Receiver Firmware

Important

Method 1, 2, and 3 apply to Happymodel EP, Happymodel ES900RX, Method 1 applies to Happymodel PP, Happymodel ES915 RX, Method 4 applies to Happymodel PP, Happymodel ES915 RX

3.1 Method 1: Through Passthrough

1. Ensure you have properly completed receiver wiring and your flight controller is configured.

Important

This is an important step to ensure a successful update. If you have not completed these operations, please go back.

2. Connect the receiver to the flight controller board and connect to the computer via a USB data cable.

3. Launch ExpressLRS Configurator on your computer, ensure the Official Releases tab is active, and select the Released version to flash to the RX module.

4. Select the Device Category and Device target that match your hardware.

If using Happymodel EP:

• Device Category: Happymodel 2.4 GHz

• Device: HappyModel EP1/EP2 2.4GHz RX

  • HappyModel EP Dual 2.4GHz RX

If using Happymodel ES900RX:

• Device Category: Happymodel 900 MHz

• Device: HappyModel ES900 RX

  • HappyModel ES900 Dual RX

If using Happymodel****PP :

• Device Category: Happymodel 2.4 GHz
• Device: HappyModel PP 2.4GHz RX

If using Happymodel ES915 RX;

• Device Category: Happymodel 900 MHz
• Device: HappyModel ES915 RX

5. Set the Flashing Method to BetaflightPassthrough

6. Set the firmware options for the device.

• Regulatory Domain (Required, select the domain suitable for your location or country/region where you will be flying)
• Binding Phrase (Optional but highly recommended. Note this phrase as it should be the same on your other devices, otherwise they won't bind or sync)
• Local WiFi Network Credentials (Optional. Will be used when the device enters WiFi mode next time).

7. Click the Flash button.

8. Wait for the process to complete. A green success bar will appear in ExpressLRS Configurator.

9. After a few seconds, the LED on the receiver should return to slow-blink LED mode.

3.2 Method 2: Through UART

1. Connect the receiver to a UART adapter. You need to disconnect the receiver from the flight controller and connect it to the UART/FTDI adapter as shown below.

2. If your receiver has a Boot Pad instead of a Boot Button, solder the Boot Pad together or ground it. If your receiver has a Boot Button, find it and press and hold it.

3. Insert the UART adapter into a USB port on your computer.

• The LED on the receiver should be solid on. If it's blinking rapidly, repeat the previous step.
• After the LED on the receiver is solid on, release/unpress the button on the receiver (if any).

4. Drivers need to be installed the first time you use a UART adapter. Common USB to UART adapter chips include: CP210x, FTDI FT232, CH340 and CH9102 (driver download page links).

5. Go to your computer's Device Manager to check if the UART adapter is properly detected as a USB to UART device.

6. Launch ExpressLRS Configurator on your computer, ensure the Official Releases tab is active, and select the Released version to flash to the RX module.

7. Select the Device Category and Device target that match your hardware.

If using Happymodel EP:

• Device Category: Happymodel 2.4 GHz

• Device: HappyModel EP1/EP2 2.4GHz RX

  • HappyModel EP Dual 2.4GHz RX

If using Happymodel ES900RX;

• Device Category: Happymodel 900 MHz

• Device: HappyModel ES900 RX

  • HappyModel ES900 Dual RX

8. Set the Flashing Method to UART

9. Set the firmware options for the device.

• Regulatory Domain (Required, select the domain suitable for your location or country/region where you will be flying)
• Binding Phrase (Optional but highly recommended. Note this phrase as