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Happymodel ES900RX

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ES900RX

Wiring up your receiver

Note: There are Flight Controllers that will pull the RX pads LOW which will put the ESP-based receivers into Bootloader Mode unintentionally. A solid LED light on these receivers even with the TX module off is a sign they are in Bootloader Mode. If this is the case, rewire the receiver to a different UART.

HM2400 connection

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

pull up

Also of note is that the ESP-based receivers require their Boot pads (see figure above) be bridged on first time Passthrough Flash from their factory firmwares. After the first passthrough flashing, the bridge needs to be removed, and is no longer needed for subsequent passthrough flashing.

Flashing via Wifi doesn't need the Boot Pads bridged. Moreover, if it is bridged, the receiver will stay in bootloader mode and won't activate its WiFi Mode.

Configuring your Flight Controller

See this page on how your flight controller should be configured. These settings apply on both INAV and 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 Passthrough

Target: HappyModel_RX_ES900RX_via_BetaflightPassthrough

Device Category: Happymodel 900 MHz

Device: HappyModel RX ES900RX

via Passthrough

With the receiver wired properly to your FC, select the right target and set your Firmware Options in the ExpressLRS Configurator, then click on Build and Flash. First time compiles naturally takes a while but if you do the prep work properly, you'll be greeted with the Success message soon enough!

Flashing via Wifi

Target: HappyModel_RX_ES900RX_via_Wifi

Device Category: Happymodel 900 MHz

Device: HappyModel RX ES900RX

via WiFi

Method 1

(Recommended as first-flash method)

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_RX_ES900RX-<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.

Build

Power 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 Hotspot Mode.

LEDSEQ_WIFI_UPDATE

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.

WiFi 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_RX_ES900RX-<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 the 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 and your module and receiver should now be bound (given you have updated the Tx Module as well, and that they have the same binding phrase and options).

Update for version 2.0

Once you have updated to firmware version 2.0 or newer, the Web Update page on the Hotspot will get a few updates of its own. It will get the Update progress bar, and a Popup will be shown for Success or Error messages. Additionally, you can configure Home Network SSID and Password if you chose not to use ExpressLRS Configurator to set them. Once these are set, you can use the two methods below.

JoinNetwork

Method 2

Note: This method will only work once the Home Network SSID and Password has been configured with the receiver

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_RX_ES900RX-<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.

Build

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.

LEDSEQ_WIFI_UPDATE

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:

Firmware Update

Drag-and-drop the HappyModel_RX_ES900RX-<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

Note: This method will only work once the Home Network SSID and Password has been configured with the receiver

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.

LEDSEQ_WIFI_UPDATE

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.

Build & Flash

RXUpload Log

ES915/868RX (Discontinued)

Flashing via Passthrough

Target: HappyModel_RX_ES915RX_via_BetaflightPassthrough

Device Category: Happymodel 900 MHz

Device: HappyModel RX ES915RX

stm Passthrough

ES915RX

Once wired properly to your FC as shown above, connect your FC to USB. Did your receiver powered up too (with both LEDs lit)? If so, disconnect USB, hold the bind button on your receiver, and reconnect to USB. The LED should start alternating between the Green and Red LEDs. Once it's alternating, you can then let go of the Bind Button.

If your receiver didn't get powered from USB, have a lipo ready and continue with the next steps. On the ExpressLRS Configurator, with your Firmware Options set, click on Build & Flash. Like on the TX module, it will take a while on the first time. Watch out for the Passthrough Init stage. This stage will check your FC Configuration for the Serial RX UART (Software Inversion via "set serialrx_inverted" and Half Duplex mode via "set serialrx_halfduplex" will be checked; both should be off.)

Build & Flash

Once Retry... lines appear, connect a LiPo if your receiver isn't powered by the USB (i.e. power up your receiver and FC). On subsequent flash, you can have the LiPo plugged in and receiver powered up from the start.

Wait for this process to finish. It's done once the "Success" prompt is shown.

Target: HappyModel_RX_ES915RX_via_STLINK

Device Category: Happymodel 900 MHz

Device: HappyModel RX ES915RX

via STLink

ES915RX

Connect your STLink into GND, DIO, CLK, 3V3 of the receiver. These pads are marked clearly in the top left of the image above.

Using the correct target specific for your receiver, set your Firmware Options and hit Build & Flash on the ExpressLRS Configurator.

Build & Flash

Once done, wire your receiver to your Flight Controller. Passthrough flashing can now be used for updating the receiver.