14.1.1.5. Restoring the bootloader¶

A normal firmware flash never touches the bootloader, so an interrupted firmware update is almost always recoverable: re-run the same flashing command from Flashing the firmware (dfu-util -w waits for the device) or re-run Load Custom Firmware while the camera is still in its bootloader. This page covers the rarer case where the bootloader itself is damaged and the camera no longer enumerates as a DFU device on reset.

The bootloader lives in a separate flash region from the firmware and filesystem, and every OpenMV-branded camera has a hardware path back, so a camera is difficult to render permanently unrecoverable. The Arduino boards are the only exception – their bootloaders are fixed and not user-restorable.

OpenMV IDE automates all of these recovery procedures, prompting you through the hardware steps (jumpers, switches, buttons) along the way. The sections below document what it does for each camera family, for when you want to run the recovery yourself.

14.1.1.5.1. STM32 cameras (BOOT–RST jumper)¶

For the STM32 OpenMV cameras (M4, M7, H7, H7 Plus, Pure Thermal):

Disconnect the camera.
Connect a jumper wire between the BOOT and RST pins.
Reconnect. The camera now enumerates as the ST system DFU device (0483:df11), independent of the damaged firmware.
Reflash the bootloader only – OpenMV IDE Load Custom Firmware with bootloader.bin, or:
```
dfu-util -w -d ,0483:df11 -a 0 -s 0x08000000 -D bootloader.bin
```
Remove the jumper and reconnect.
Flash the firmware normally (see Flashing the firmware).

14.1.1.5.2. OpenMV Cam N6 (BOOT–VCC jumper)¶

Disconnect the camera.
Connect a jumper wire between the BOOT and VCC pins.
Reconnect. The camera now enumerates as the ST system DFU device (0483:df11), independent of the damaged bootloader.
Reflash with STM32CubeProgrammer (included in the OpenMV SDK), using the flash-layout descriptor shipped alongside bootloader.bin – it rewrites the first-stage bootloader, the external-flash loader, and the bootloader:
```
STM32_Programmer_CLI -c port=USB1 -d OPENMV_N6/FlashLayout.tsv
```
Remove the jumper and reconnect.
Flash the firmware normally (see Flashing the firmware).

14.1.1.5.3. OpenMV Cam RT1062¶

Recreating the RT1062 secure bootloader requires entering the chip’s ROM serial-download (SDP) mode with a jumper, staging a RAM flashloader, then rewriting the flash configuration block, the SBL, and the firmware. The manual sequence:

Disconnect the camera, jumper the SBL and 3.3V pins, and reconnect. The chip enumerates in SDP ROM mode (0x1FC9:0x0135).

Stage and start the RAM flashloader:

sdphost -u 0x1FC9,0x0135 -- write-file 0x20001C00 sdphost_flash_loader.bin
sdphost -u 0x1FC9,0x0135 -- jump-address 0x20001C00

The camera now answers as the flashloader (0x15A2:0x0073). Configure the external flash, write the flash configuration block, then write the SBL:

blhost -u 0x15A2,0x0073 -- fill-memory 0x2000 4 0xC0000008 word
blhost -u 0x15A2,0x0073 -- configure-memory 9 0x2000
blhost -u 0x15A2,0x0073 -t 120000 -- flash-erase-region 0x60000000 0x1000
blhost -u 0x15A2,0x0073 -- fill-memory 0x2000 4 0xF000000F word
blhost -u 0x15A2,0x0073 -- configure-memory 9 0x2000
blhost -u 0x15A2,0x0073 -t 120000 -- flash-erase-region 0x60001000 <sbl_size>
blhost -u 0x15A2,0x0073 -- write-memory 0x60001000 blhost_flash_loader.bin

Write the firmware and set the boot-source fuse so the chip boots the new SBL from external flash:

blhost -u 0x15A2,0x0073 -t 120000 -- flash-erase-region 0x60040000 <firmware_size>
blhost -u 0x15A2,0x0073 -- write-memory 0x60040000 firmware.bin
blhost -u 0x15A2,0x0073 -- efuse-program-once 0x06 00000010
blhost -u 0x15A2,0x0073 -- reset

Remove the jumper and power-cycle the camera.

Warning

efuse-program-once 0x06 00000010 is a one-time, irreversible fuse write that sets the device to boot from external flash. This is another reason to let OpenMV IDE perform RT1062 bootloader recovery rather than running the sequence by hand.

14.1.1.5.4. OpenMV AE3¶

The AE3’s secure bootloader is not restored over USB DFU. It is rewritten into the chip’s MRAM with Alif Semiconductor’s SE Tools (bundled with OpenMV IDE) over a serial ISP connection. This is an interactive, recovery-only procedure – not a routine flashing method – and it is error-prone by hand; of everything on this page, it is the one to leave to OpenMV IDE.

Connection. The SE Tools talk to the AE3 over its debug adapter’s serial ISP port – an FTDI 0403:6015 or a CH340 1A86:55D3 interface, together with a J-Link. Recovery requires putting the device in recovery mode: enable the on-board recovery switch.

SE Tools. OpenMV IDE bundles these Alif executables. They share two config files – isp_config_data.cfg and global-cfg.db – created by maintenance on first connection:

Tool	Purpose
`maintenance`	Query the Secure Enclave (`maintenance -opt sesbanner` reads its version) and place the device in recovery mode.
`updateSystemPackage`	Update the Secure Enclave system package when it is older than the version the firmware requires.
`app-gen-toc`	Generate the table-of-contents (TOC) image (used for an application-only write).
`app-write-mram`	Write image(s) to MRAM – the step that restores the bootloader.

Procedure:

Connect to the AE3 with maintenance; it prompts for the serial port and the device type, creating isp_config_data.cfg and global-cfg.db for the other tools.
If the Secure Enclave system package is out of date, updateSystemPackage updates it; power-cycle when prompted.
app-write-mram -i "bootloader.bin 0x80000000 firmware_pad.toc 0x8057E000" writes the bootloader and TOC into MRAM.
The AE3 re-enumerates as the 37C5:96E3 DFU device. Run the normal four-image flash from OpenMV AE3: dfu-util to load the application.
Power-cycle the camera and turn the recovery switch back off.

Note

OpenMV IDE handles much more than this happy path – a corrupted Secure Enclave firmware, a bad bootloader, and the other failure states each need their own recovery steps, and a lot can go wrong along the way. If the manual steps above don’t bring the camera back, use OpenMV IDE to recover it.