zephyr-stm32n6-ai-people-detection : Boot from Flash not working

[geethapriya]

Board: STM32N6570-DK
IDE/Toolchain: Zephyr RTOS + west, Zephyr SDK 0.17.4
Repository: stm32-hotspot/zephyr-stm32n6-ai-people-detection
OS: Windows 11

I am trying to run the STM32N6 AI people detection application in flash boot mode using MCUboot RAM_LOAD as described in the README. The application runs correctly in debug/development mode (west debug), but does not boot at all when built and flashed for boot-from-flash mode.

No output is seen on the UART console after the MCUboot banner — inference never starts.

Steps to Reproduce:

Following the README exactly:

# 1. Build
west build -b stm32n6570_dk --sysbuild app -DSB_CONFIG_MCUBOOT_MODE_RAM_LOAD=y -p
# 2. Flash model weights (board in Development Mode: Boot 0: L and Boot 1: H)
west flash-weights
# 3. Flash MCUboot + app (board in Development Mode)
west flash
# 4. Move boot switches to Flash Boot mode (Boot 0: L and Boot 1: L)
# 5. Power cycle
```
---

### Observed Behaviour

After power cycle in Flash Boot mode, the UART console is silent — no MCUboot banner, no application output. Inference does not run.

Debug mode works perfectly with `west debug` and `(gdb) c`.

[Julian E.]

Hi @geethapriya,

This was tested on:

• linux
• windows + wsl

We checked again and did not find any issue.

What are you using?

Have a good day,

Julian

[emmanuel_]

Dear @geethapriya,

I worked with the repository stm32-hotspot/zephyr-stm32n6-ai-people-detection on Windows 11 using Zephyr. After running west init -m https://github.com/stm32-hotspot/zephyr-stm32n6-ai-people-detection and west update, I also tried west flash without success.

While exploring the project directory, I noticed that in the folder:
C:\Users\papam\zephyr-stm32n6-demo\zephyr-stm32n6-ai-people-detection\Binary\

the file zephyr-stm32n6-ai-people-detection-dk.hex needed to be programmed directly using STM32CubeProgrammer. Miraculously, the application works perfectly when programmed this way.

Cheers

Emmanuel

[geethapriya]

Hi Emmanuel,

Yes, the C:\Users\papam\zephyr-stm32n6-demo\zephyr-stm32n6-ai-people-detection\Binary\zephyr-stm32n6-ai-people-detection-dk.hex works fine when flashed using STMCube Programmer.

I wanted to make code changes and build the application again and flash it using west flash/ cube programmer, but they don't work - most likely because the mcuboot's bin file doesn't load the image/boot properly. The final hex file at zephyr-stm32n6-demo\zephyr-stm32n6-ai-people-detection\Binary\ is prebuilt I guess and when we make code changes it doesn't generate a zephyr-stm32n6-ai-people-detection-dk.hex automatically. The newly generated hex/bines can be found in build directory.

Thanks,

Geetha Priya

[geethapriya]

Hi Julian,

I tried it on Windows (without WSL). Can you please try flashing the bootloader bin, application bin and model hex separately via Cube Programmer and confirm if it works.

Steps to reproduce the error:

1. Flash "C:\zephyr-stm-ai-example\workspace\zephyr-stm32n6-ai-people-detection\build\mcuboot\zephyr\zephyr.signed.bin" at address 0x70000000

2. Flash "C:\zephyr-stm-ai-example\workspace\zephyr-stm32n6-ai-people-detection\build\app\zephyr\zephyr.signed.bin" at address 0x70010000

3. Flash "C:\zephyr-stm-ai-example\workspace\zephyr-stm32n6-ai-people-detection\app\Model\network_data.hex"

The west flash method shared in the repo's README also doesn't seem to work.

Thanks,

Geetha Priya

[emmanuel_]

Hi,

I was able to try it by following the documentation in the correct directory and activating the virtual environment (venv). Then I built the project and ran west debug. Press ENTER on the keyboard, then press the c key (to continue). In the end, the program works well for me (display, detection, and Zephyr logo).

https://github.com/stm32-hotspot/zephyr-stm32n6-ai-people-detection?tab=readme-ov-file#boot-modes

in virtual environment : 

PS C:\Users\papam\zephyr-stm32n6-demo\zephyr-stm32n6-ai-people-detection> ls

Directory: C:\Users\papam\zephyr-stm32n6-demo\zephyr-stm32n6-ai-people-detection

Mode LastWriteTime Length Name
---- ------------- ------ ----
d---- 3/17/2026 12:27 PM _htmresc
d---- 3/17/2026 12:27 PM app
d---- 3/17/2026 12:27 PM Binary
d---- 3/19/2026 7:54 PM build
d---- 3/17/2026 12:27 PM Lib
-a--- 3/17/2026 12:27 PM 715 LICENSE.md
-a--- 3/17/2026 12:27 PM 5554 README.md
-a--- 3/17/2026 12:27 PM 1058 Release_Notes.md
-a--- 3/17/2026 12:27 PM 743 west.yml

PS C:\Users\papam\zephyr-stm32n6-demo\zephyr-stm32n6-ai-people-detection> C:\Users\papam\zephyrproject\.venv\Scripts\Activate.ps1
(.venv) PS C:\Users\papam\zephyr-stm32n6-demo\zephyr-stm32n6-ai-people-detection>

 built the project

(.venv) PS C:\Users\papam\zephyr-stm32n6-demo\zephyr-stm32n6-ai-people-detection> west build -b stm32n6570_dk --sysbuild app -DSB_CONFIG_MCUBOOT_MODE_RAM_LOAD=y -p

and after :

(.venv) PS C:\Users\papam\zephyr-stm32n6-demo\zephyr-stm32n6-ai-people-detection> west debug
-- west debug: rebuilding
[0/6] Performing build step for 'app'ninja: no work to do.

[1/6] Performing build step for 'mcuboot'ninja: no work to do.

[6/6] Completed 'mcuboot'
-- west debug: using runner stlink_gdbserver

STMicroelectronics ST-LINK GDB server. Version 7.13.0
Copyright (c) 2026, STMicroelectronics. All rights reserved.

Starting server with the following options:
Persistent Mode : Disabled
Logging Level : 1
Listen Port Number : 61234
Status Refresh Delay : 15s
Verbose Mode : Disabled
SWD Debug : Enabled
InitWhile : Enabled

GNU gdb (Zephyr SDK 0.17.4) 12.1
Copyright (C) 2022 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARWaiting for debugger connection...
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This GDB was configured as "--host=x86_64-host_w64-mingw32 --target=arm-zephyr-eabi".
Type "show configuration" for configuration details.
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For help, type "help".
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Reading symbols from C:/Users/papam/zephyr-stm32n6-demo/zephyr-stm32n6-ai-people-detection/build/app/zephyr/zephyr.elf...
Debugger connected
Waiting for debugger connection...
Remote debugging using :61234
0x18003a1a in ?? ()
Loading section rom_start, size 0x748 lma 0x34000000
Loading section text, size 0x38a54 lma 0x34000748
Loading section .ARM.exidx, size 0x8 lma 0x3403919c
Loading section initlevel, size 0x180 lma 0x340391a4
Loading section device_area, size 0x4c0 lma 0x34039324
Loading section _static_thread_data_area, size 0x30 lma 0x340397e8
Loading section flash_driver_api_area, size 0x18 lma 0x34039818
Loading section gpio_driver_api_area, size 0x24 lma 0x34039830
Loading section i2c_driver_api_area, size 0x18 lma 0x34039854
Loading section reset_driver_api_area, size 0x10 lma 0x3403986c
Loading section clock_control_driver_api_area, size 0x1c lma 0x3403987c
Loading section display_driver_api_area, size 0x2c lma 0x34039898
Loading section video_driver_api_area, size 0x78 lma 0x340398c4
Loading section uart_driver_api_area, size 0x14 lma 0x3403993c
Loading section log_const_area, size 0x108 lma 0x34039950
Loading section log_backend_area, size 0x10 lma 0x34039a58
--Type <RET> for more, q to quit, c to continue without paging--

on the keyboard  : ENTER

Loading section input_callback_area, size 0xc lma 0x34039a68
Loading section rodata, size 0x60df4 lma 0x34039a80
Loading section datas, size 0x438d lma 0x3409a880
Loading section sw_isr_table, size 0x610 lma 0x3409ec10
Loading section device_states, size 0x4c lma 0x3409f220
Loading section log_mpsc_pbuf_area, size 0x3c lma 0x3409f26c
Loading section log_msg_ptr_area, size 0x4 lma 0x3409f2a8
Loading section k_msgq_area, size 0x58 lma 0x3409f2ac
Loading section k_sem_area, size 0x14 lma 0x3409f304
Loading section video_device_area, size 0x40 lma 0x3409f318
Loading section .last_section, size 0x4 lma 0x3409f358
Start address 0x34009770, load size 652093
Transfer rate: 95 KB/sec, 9880 bytes/write.

on the keyboard type c   

(gdb) c
Continuing.

Cheers

Emmanuel

[geethapriya]

Hi @emmanuel_ ,

The developer mode: west debug

works for me as well when I follow the same steps. It is not working in boot from flash mode: west flash

Thanks,

Geetha Priya