Hello everyone — I’m running an AI image-classification model on the STM32N6570-DK and I’m stuck with a reproducible problem. The first inference completes successfully (EVENT_DONE), but on the second run the code gets stuck inside the runtime (run_epoch) with no event returned; on the third attempt it again stalls and then triggers a HardFault. I followed the ST tutorial here when creating the project:
https://community.st.com/t5/stm32-mcus/how-to-build-an-ai-application-from-scratch-on-the-stm32n6570-dk/ta-p/825591
Below are the full details, steps to reproduce, debug info, things I’ve tried, and the files I’ve attached.
Environment
Board: STM32N6570-DK
Model: Image Classification (generated with STM32Cube.AI)
Model and weights: placed in xSPI1 / xSPI2 (QSPI/XSPI) and also copied to internal SRAM for some buffers
SRAM clocks: enabled for SRAM3, SRAM4, SRAM5, SRAM6
Toolchain: STM32Cube IDE - Latest version
CubeMX / Cube.AI version: Latest Version
RTOS: (bare-metal / FreeRTOS) : Bare-metal
What I did (exact steps)
Followed ST tutorial linked above to generate the project and AI code.
Integrated the Image Classification model and generated C sources/weights with Cube.AI.
Placed model weights and buffers in external XSPI1/XSPI2 and also set some buffers in internal SRAM.
Enabled clocks for SRAM3/4/5/6 so the SRAM regions are accessible.
Confirmed the input buffer address is readable after SRAM clocks are enabled.
Run the code:
1st inference: completes normally — returns event EVENT_DONE.
2nd inference: code enters run_epoch and blocks (no event).
3rd inference: same block in run_epoch, then Hard Fault occurs.
I have attached:
Observed behavior (more details)
First ai_run returns as expected.
On subsequent calls, execution enters the AI runtime’s run_epoch (or similar), but the runtime never completes or calls the EVENT_DONE callback.
Eventually a Hard Fault occurs; the first HardFault image shows stacked registers (I’ll attach the screenshot).
There are no obvious warnings during build; project builds clean.
