The flight controllers that support app-based firmware flashing are:

SpeedyBee WING APP V2 paired with SpeedyBee WING WEXT PRO.

1. Detailed Instructions for Removing Peripherals

• Disconnect the battery.
• Remove all peripherals, leaving only the expansion board connected to the flight controller.
• Connect the flight controller to power using a USB data cable through the expansion board.
• Check the option "I have unplugged the peripheral device."
• Click "Connect."

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2. Analysis of the Reason for Removing Peripherals

When the flight controller firmware on the SpeedyBee F405 WING APP V2 is functioning properly, the SpeedyBee APP can automatically enter DFU mode when flashing the firmware.

However, certain peripherals may interfere with the flight controller's boot mode pins (especially the BOOT0 or USB level detection), preventing the flight controller from entering DFU mode or from being recognized as an STM32 DFU device. Therefore, removing peripherals ensures that no such interference occurs during the process.

The following factors may prevent the flight controller from entering DFU mode:

Interference Sources	Explanation of Interference Sources
Serial Peripherals (e.g., GPS, Receiver)	These peripherals occupying the TX/RX lines may interfere with the bootloader's ability to make a proper determination.
I2C/SPI Devices (e.g., Compass)	Level shifting of signals can cause the flight controller to misinterpret the situation and think it is in "external boot" mode.
Unisolated Peripheral Power Supply	When peripherals are not isolated, they may "back-power" the flight controller through the signal lines, causing instability.
High-current Modules (e.g., HD Video Transmission, LiDAR)	These modules may overload the USB power supply, resulting in failure to recognize the flight controller.