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.

What You'll Need

• ARK 4IN1 ESC

• ST-Link V2 or V3 programmer

• Computer running Windows or Ubuntu

• AM32 bootloader file

Hardware Setup

Connect and program each MCU. If your ESC is powered with a power supply or battery do not connect the 3.3V

• ST-Link SWDIO → Corresponding ESC SWDIO pin

• ST-Link SWCLK → Corresponding ESC SWCLK pin

• ST-Link GND → Pin 10 (GND)

• ST-Link 3.3V → Pin 1 (3.3V) — do not connect if ESC is externally powered

Software Installation

Windows

Download the ST-Link Utility from the ST-LINK website.

Open the GUI and follow the ST Documentation to program the MCU.

Ubuntu

Follow the instructions on the official ST-LINK github page to install the stlink tools.

Test the Connection

st-info --probe

You should see output similar to:

Found 1 stlink programmers
  version:    V2J45S7
  serial:     543C0A135550
  flash:      32768 (pagesize: 1024)
  sram:       4096
  chipid:     0x0440
  dev-type:   STM32F03x/STM32F05x

If you see an error, check your wiring.

Erase Flash Memory

Before flashing the bootloader, erase the flash:

st-flash erase

Flash the Bootloader

Navigate to the directory containing AM32_F051_BOOTLOADER_PB4.bin, then flash it:

st-flash write AM32_F051_BOOTLOADER_PB4.bin 0x08000000

You should see output indicating successful flash:

st-flash 1.8.0
2025-10-01T12:34:56 INFO common.c: F0xx (Low/Medium): 4 KiB SRAM, 32 KiB flash in at least 1 KiB pages.
file AM32_F051_BOOTLOADER_PB4.bin md5 checksum: a3b4c5d6e7f8g9h0i1j2k3l4m5n6o7p8, stlink checksum: 0x001234ab
2025-10-01T12:34:56 INFO common.c: Attempting to write 6144 (0x1800) bytes to stm32 address: 134217728 (0x8000000)
2025-10-01T12:34:56 INFO common.c: Flash written and verified! jolly good!