ST X-CUBE-SBSFU - External Flash on STM32 H7 B3 Devices; Figure 55. JTAG Connection Capability on STM32 H7 B3 Devices; Figure 56. STM32 H7 B3: MPU Isolation + Secure User Memory, with External Flash

STM32H7 Series specificities UM2262
90/94 UM2262 Rev 6
Figure 55. JTAG connection capability on STM32H7B3 devices
I.3 External Flash on STM32H7B3 devices
The STM32H7B3xxx microcontrollers offer the possibility to store the firmware images in an
external memory in case the user application requires more memory size than what it is
available in internal Flash memory.
OTFDEC write-only key registers are configured by Secure Engine protected enclave
before starting user application as illustrated in
Figure 56.
Figure 56. STM32H7B3: MPU isolation + secure user memory, with external Flash
During installation process, Slot #0 firmware remains encrypted to ensure the confidentiality.
On-the-fly decryption is performed by OTFDEC peripheral during the execution of the user
application from the external Flash memory.