Flash Bootloader

This page details flashing the bootloader firmware using am32-configurator or SWD.

Flashing Bootloader via AM32

You can update the bootloader using the AM32 Configurator. Once connected select "Flash firmware" and select the "Bootloader" tab. Download the AM32-bootloader-updaters-amj.zip from the AM32-bootloader release artifacts. Select the AM32_F051_BL_UPDATER_PB4_V15.amj.

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Flashing Bootloader via SWD

If you're flashing an ESC without firmware or the firmware has become corrupted, you can reflash the ESC with SWD to bring it back to a fresh state.

For detailed instructions on ST-LINK setup, software installation, and usage, see the ST-LINK Flashing Guide.

What You'll Need

• ARK 4IN1 ESC

• ST-LINK V3 Mini (recommended) or ST-LINK V2

• Computer running Windows or Ubuntu

• AM32 bootloader file

Hardware Setup

The ARK 4IN1 ESC has 4 separate STM32F051 microcontrollers (one per motor channel), each with their own SWD interface on a single 10-pin debug connector. See the pinout for the full connector diagram.

Pin	Signal
1	3.3V
2	SWDIO 1 (ESC 1)
3	SWCLK 1 (ESC 1)
4	SWDIO 2 (ESC 2)
5	SWCLK 2 (ESC 2)
6	SWDIO 3 (ESC 3)
7	SWCLK 3 (ESC 3)
8	SWDIO 4 (ESC 4)
9	SWCLK 4 (ESC 4)
10	GND

To flash each ESC, connect your ST-LINK to the corresponding SWDIO/SWCLK pair. For example, to flash ESC 1:

ST-LINK Pin	Debug Connector Pin	Signal
SWDIO	Pin 2	SWDIO 1
SWCLK	Pin 3	SWCLK 1
GND	Pin 10	GND
3.3V (optional)	Pin 1	3.3V

If your ESC is powered from a battery or power supply, do not connect the 3.3V line from the ST-LINK.

Repeat the process for ESC 2-4 using their respective SWDIO/SWCLK pins (4/5, 6/7, 8/9).

Flash the Bootloader

Flash each ESC MCU with the bootloader binary:

st-flash write AM32_F051_BOOTLOADER_PB4.bin 0x08000000