wolfSSL is announcing wolfBoot support for the STM32N6 series added in PR #720, starting with the NUCLEO-N657X0-Q development board (STM32N657X0H). The STM32N6 is ST’s first Cortex-M55 microcontroller, designed for high-performance edge AI workloads with a dedicated Neural Processing Unit (NPU). wolfBoot provides cryptographic signature verification and secure firmware updates on this new platform.
About the STM32N6
The STM32N6 is built around the Arm Cortex-M55 core running at 600 MHz currently but can be run at up to 800 MHz. It targets edge AI applications such as vision, audio classification, and anomaly detection. Unlike most STM32 parts, the N6 has no internal flash. All firmware resides on external NOR flash connected via the high-speed XSPI2 interface, with over 4.2MB of on-chip SRAM available for code execution and data.
This flash-less architecture makes the STM32N6 a great fit for applications that need large, updateable firmware images without being constrained by internal flash size, while still benefiting from the performance of a modern Cortex-M55 core with Helium vector extensions.
wolfBoot on the STM32N6
wolfBoot serves as the First Stage Boot Loader (FSBL) on the STM32N6. The on-chip Boot ROM copies wolfBoot from external NOR flash into SRAM and executes it. wolfBoot then verifies the application image signature and boots the application, which runs directly from external flash via Execute-In-Place (XIP) memory-mapped mode.
The wolfBoot binary comes in at approximately 22KB default, well within the 128KB FSBL limit. The entire port is self-contained with no external dependencies: no STM32Cube HAL, no CMSIS headers, no RTOS required.
Signature verification uses ECC256 with SHA-256, and the port supports A/B firmware updates with swap-based rollback, all operating on the external NOR flash.
Tested Hardware
- Board: NUCLEO-N657X0-Q (STM32N657X0H, MB1940)
- Flash: Macronix MX25UM51245G, 64MB NOR on XSPI2
- Build + Flash: make && make flash using OpenOCD with ST-Link
Questions or issues?
If you have questions about any of the above, please contact us at facts@wolfssl.com or call us at +1 425 245 8247.
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