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 reflesh 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

• Power supply for the ESC (3s-8s LiPo or bench power supply, 6-33V)

• Computer running Windows or Ubuntu 22.04+

• AM32 bootloader file (AM32_F051_BOOTLOADER_PB4.bin)

Hardware Setup

You will flash one MCU at a time, connecting three wires from your ST-Link to the appropriate pins on the debug connector:

• ST-Link SWDIO → Corresponding ESC SWDIO pin

• ST-Link SWCLK → Corresponding ESC SWCLK pin

• ST-Link GND → Pin 10 (GND)

Important: Do NOT connect the 3.3V pin from the ST-Link. Power the ESC through its main battery input (6-33V). It's recommended to flash without motors connected.

Software Installation

Windows

1. Download the latest Windows release from the stlink releases page

2. Choose the correct version for your system (i686 for 32-bit or x86_64 for 64-bit)

3. Extract the archive to C:\Program Files\stlink or C:\Program Files (x86)\stlink

4. Add the stlink folder to your system PATH:

   • Open System Properties → Advanced → Environment Variables

   • Edit the PATH variable and add the stlink installation directory

   • Click OK to save

USB Driver Setup:

Windows requires USB driver installation for the ST-Link:

1. Download and install Zadig

2. Connect your ST-Link to your computer

3. Open Zadig and select your ST-Link device from the dropdown

4. Select WinUSB driver

5. Click "Replace Driver" or "Install Driver"

Verify Installation:

Open Command Prompt or PowerShell and run:

st-info --version

Ubuntu

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

Flashing Process

You must flash the bootloader to each of the four MCUs individually.

Step 1: Connect to MCU

For each ESC:

1. Power off the ESC

2. Connect your ST-Link to the corresponding SWD pins

3. Power on the ESC (6-33V on main battery input)

4. Connect the ST-Link to your computer via USB

Step 2: Verify Connection

Test the connection to ensure the MCU is detected:

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 and ensure the ESC is powered.

Step 3: Erase Flash Memory

Before flashing the bootloader, erase the flash:

st-flash erase

Step 4: 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!