How to Flash Ghost Atto Receiver with ExpressLRS Firmware Using STlink Tool

In this tutorial, we will guide you through the process of flashing ExpressLRS firmware to ImmersionRC Ghost Atto Receiver using the STlink V2 Tool. This method also applies to other receivers, like Jumper or Frsky R9. We will break down the process into easy-to-follow steps.

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Warning: as far as I know, there’s no going back. Once you flash ExpressLRS there’s no easy way to flash Ghost firmware.

There’s absolutely no need to buy the Ghost Atto receiver to use ExpressLRS, there are a lot of cheaper alternative that are designed for ExpressLRS. I’m flashing my Ghost Atto receiver because I no longer use Ghost and don’t want them to be sitting around.

Purchasing a STLink Tool

You will need a STM32 STLink Tool that allows you to upload firmware file directly to the processor via the STM32 ST-Link Utility program.

Buy the ST-Link V2 Tool here:

• Amazon: https://amzn.to/3XpI3f4
• AliExpress: https://s.click.aliexpress.com/e/_DCalVOh

Preparing the Receiver

If your receiver is connected to a flight controller, remove it from the drone so you can easily access the four small solder pads as labelled in the above image.

Identify the pinout on the receiver for 3.3V, ground (GND), I/O (DIO), and Clock (CLK). Do not power the receiver from both 5V and 3.3V at the same time, pick one. Connect the receiver to the STlink V2 Tool:

• 3.3V to 3.3V
• GND to GND
• SWCLK to CLK
• SWDIO to DIO

Removing Protection

Download and install the STM32 ST-Link Utility: https://www.st.com/en/development-tools/stsw-link004.html

Connect the receiver to the STLink tool, and plug it into your computer and launch the STM32 Link Utility. Go to Target > Option Bytes.

Remove the read protection by switching “Read out Protection” to level 0.

Then click “Unselect all” under Flash sectors protection, and click ‘Apply’ to save the changes.

After getting the “Option bytes udated successfully” message, you can now close the STM32 ST-LINK Utility program.

Flashing ExpressLRS

Download and install the ExpressLRS Configurator: https://oscarliang.com/setup-expresslrs-2-4ghz/#Download-ExpressLRS-Configurator

Open the configurator and select the appropriate branch and target for your receiver, in this case, ImmersionRC Ghost and GHOST ATTO 2400 RX. Under Flashing method, select STLink.

Configure your binding phrase, connection options, and telemetry settings as desired. This section explains what the settings mean: https://oscarliang.com/setup-expresslrs-2-4ghz/#Compile-and-Flash-TX-Firmware

Click ‘Build and Flash’ to start the flashing process.

Wait for the process to complete, during flashing, the status LED on the ST-Link programmer should blink rapidly. This should only take less than a minute to complete.

Testing and Final Steps

Connect the receiver to your flight controller and ensure it works properly in Betaflight: https://oscarliang.com/setup-expresslrs-2-4ghz/#Connect-ELRS-Receiver-to-FC

From now on, you should be able to flash ExpressLRS to the receiver via Betaflight Pass-through as documented here: https://oscarliang.com/setup-expresslrs-2-4ghz/#Flash-RX-Firmware-via-Betaflight-Passthrough

That’s it.