Happymodel EP

Wiring up your receiver¶

The image above show the receiver pinouts and their connections. As we're dealing with UART connection, Rx on the receiver goes to a TX pad on the FC, and Tx on the receiver goes to an uninverted Rx pad on the FC.

There are Flight Controllers that put their Receiver UART's RX pads Low, which in turn, puts the ESP-based (e.g. EP1 and EP2) receivers to Bootloader mode unintentionally. One remedy is to wire them into a different UART, or wire a pull-up resistor (300-1k ohm) between the Rx pad of the FC and a 3.3v or 5v pad, as shown below.

Configuring your Flight Controller¶

To configure your flight controller properly, please go through Configure FC page. These settings apply on INAV, Betaflight and other flight controller software.

Ports Tab should be setup so that Serial RX is on the UART where you have soldered the receiver.

Receiver protocol is CRSF with serialrx_inverted = off and serialrx_halfduplex = off.

The next step will not be able to proceed properly and you'll have issues later if any of these are set differently. Once you have configured your Flight Controller software, close its Configurator and unplug-replug the USB cable from the FC or your computer. This will refresh the connection and you'll be ensured that the port is not busy (of high importance with the Passthrough Flashing Method).

Flashing via WiFi¶

• Target: HappyModel_EP_2400_RX_via_WIFI

• Device Category: Happymodel 2.4 GHz

• Device: HappyModel EP 2400 RX

Method 1¶

(Recommended as first-flash method)

Before your proceed, make sure you have the receiver wired properly to your FC.

Build the firmware using the ExpressLRS Configurator using the correct Target and Firmware Options. Once done, it should open a new window where the HappyModel_EP_2400_RX-<version>.bin is. Do not close this window so you can easily navigate to it once it's time to upload the firmware into the receiver.

Power your Flight Controller by either connecting a LiPo or attaching the USB cable (if receiver gets powered from USB via a 4v5 pad). Receiver's LED will blink slow at first, and after 20s or 30s (can be adjusted via ExpressLRS Configurator using AUTO_WIFI_ON_INTERVAL), it should blink fast indicating it's on Wifi Hotspot Mode.

Connect to the Wifi Network the receiver has created. It should be named something like ExpressLRS RX with the same expresslrs password as the TX Module Hotspot.

Navigate to the same web address as the TX Module (usually http://10.0.0.1). The Firmware upload page should load, and using the File Upload Form, navigate where the correct Receiver HappyModel_EP_2400_RX-<version>.bin is (like with the Tx module, you can also drag-and-drop the firmware file into the form field or use the Browse or Choose File button). Click on Update button and the firmware file will be uploaded and the update process should commence.

A white page should load momentarily with the message Update Success! Rebooting.... Wait a little bit (you can wait until the LED on the Receiver starts to blink slowly again) and the receiver should be updated. Power cycle the receiver and it should be able to bind with your TX module now (given you have updated the Tx Module as well, and that they have the same binding phrase and options).

Method 2¶

With the receiver wired properly to your FC, select the right target and set your Firmware Options in the ExpressLRS Configurator.

Build the firmware. Once done, it should open a new window where the HappyModel_EP_2400_RX-<version>.bin is. Do not close this window so you can easily navigate to it once it's time to upload the firmware into the receiver.

Power up your Flight Controller by either connecting a LiPo or attaching the USB cable (if the receiver gets powered from USB via a 4v5 pad). The receiver's LED will blink slowly at first, and after 20s or 30s (can be adjusted via ExpressLRS Configurator using AUTO_WIFI_ON_INTERVAL), it should blink fast indicating it's on Wifi AP Mode. The fast blink will pause and flash fast once again, indicating connection to your Home Network.

Using your browser, navigate to http://elrs_rx.local/. The Wifi Update page should load. It should show your device target along with the version of the firmware it currently has.

Scroll down to the Firmware Update section, shown below:

Drag-and-drop the HappyModel_EP_2400_RX-<version>.bin file created by the ExpressLRS Configurator into the Choose File field, or manually navigate to the Folder by clicking the Choose File button. Once the correct file is selected, click the Update. Wait for the process to complete, indicated by a Green popup screen.

Wait a little bit (you can wait until the LED on the Receiver starts to blink slowly again) and the receiver should be updated.

You can now power down your Flight Controller along with the receiver.

Method 3¶

With the receiver wired properly to your FC, select the right target and set your Firmware Options in the ExpressLRS Configurator.

Power up your Flight Controller by either connecting a LiPo or attaching the USB cable (if the receiver gets powered from USB via a 4v5 pad). The receiver's LED will blink slowly at first, and after 20s or 30s (can be adjusted via ExpressLRS Configurator using AUTO_WIFI_ON_INTERVAL), it should blink fast indicating it's on Wifi Mode.

Build & Flash the firmware using the ExpressLRS Configurator. Wait for the process to complete, indicated by the "Success" prompt and the Receiver LED has gone back to the Slow Blink mode. You can now power down the Flight Controller.

Flashing via Passthrough¶

• Target: HappyModel_EP_2400_RX_via_BetaflightPassthrough

• Device Category: Happymodel 2.4 GHz

• Device: HappyModel EP 2400 RX

Make sure you have your receiver wired properly. Rx pad on the Receiver wired up to a Tx pad on the FC, and the Tx pad on the Receiver wired up to an Rx pad on the FC. Also make sure you have setup your FC firmware to use CRSF Protocol, and that the UART is not inverted or running in half duplex.

For the following steps, you should be disconnected from Betaflight or INAV Configurator. Close the FC Configurator and unplug the FC from USB to refresh the connection.

To increase the chance of a successful flashing, you will need to bridge the Boot pads on the receiver. The Wiring Guide shows where the Boot pads are. A solid LED indicates the receiver is in Bootloader mode when the TX module is OFF (Solid LED also indicates Radio+module & Receiver is bound and has connection) when the receiver is on a good UART. EP receivers with the Green LED usually don't need their boot pads bridged.

Bridging the Boot pads is no longer needed past 1.0.0-RC6.

Power your FC with a LiPo, or if receiver is powered via USB (receiver is connected to a 4v5 pad), connect the FC to your USB port. Using the ExpressLRS Configurator, with the correct Target selected and Firmware Options set, click on Build & Flash. Wait for the process to finish and you should be greeted with the "Success" banner.

Unplug USB and LiPo, and removed the solder on the bridged Boot pads. You no longer need it (past 1.0.0-RC6). Power your TX Module and then your FC to verify you are bound and has connection.

Flashing via FTDI¶

• Target: HappyModel_EP_2400_RX_via_UART

• Device Category: Happymodel 2.4 GHz

• Device: HappyModel EP 2400 RX

Wire the receiver into the FTDI, with TX on receiver connected to the Rx on the FTDI, and RX on receiver connected to the Tx of the FTDI. Wire 5V and GND of the FTDI to 5V and GND of the Receiver. Short the boot pad while powering the RX on, and release - the LED should now be solid.

Select the target and set your Firmware Options then click on Build and Flash.

Once the process is done, unsolder the receiver from the FTDI Adapter, unbridge the boot pads and rewire it into your FC as per the Wiring Guide.