Boot Configuration; Boot Mode Selection; Table 4. Boot Modes When Trustzone Is Disabled (Tzen = 0) - ST STM32U575 Series Application Note

5

Boot configuration

5.1

Boot mode selection

At startup, a BOOT0 pin, nBOOT0 and NSBOOTADDx[24:0]/SECBOOTADD0[24:0] option bytes are used to
select the boot memory address that includes:
• Boot from any address in user Flash memory
• Boot from system memory (bootloader)
• Boot from any address in embedded SRAM
• Boot from root security service (RSS)
The BOOT0 value may come from the PH3-BOOT0 pin or from an option bit depending on the value of a user
option bit to free the GPIO pad if needed.
When TrustZone
below.
nBOOT0
BOOT0
FLASH_
pin PH3
OPTR[27]
-
-
1
0
When TrustZone is enabled by setting the TZEN option bit (TZEN = 1), the boot space must be in a secure area.
The SECBOOTADD0[24:0] option bytes are used to select the boot secure memory address. A unique boot entry
option can be selected by setting the BOOT_LOCK option bit. All other boot options are ignored.
AN5373 - Rev 1
®
is disabled by resetting TZEN option bit (TZEN = 0), the boot space is as detailed in the table
Table 4. Boot modes when TrustZone is disabled (TZEN = 0)
nSWBOOT0
Boot address
FLASH_
option‑byte selection
OPTR[26]
0 1 NSBOOTADD0[24:0]
1 1 NSBOOTADD1[24:0]
- 0 NSBOOTADD0[24:0]
- 0 NSBOOTADD1[24:0]
Boot area
Boot address defined by user option
bytes NSBOOTADD0[24:0]
Boot address defined by user option
bytes NSBOOTADD1[24:0]
Boot address defined by user option
bytes NSBOOTADD0[24:0]
Boot address defined by user option
bytes NSBOOTADD1[24:0]
AN5373
Boot configuration
ST programmed
default value
Flash: 0x0800 0000
Bootloader:
0x0BF9 0000
Flash: 0x0800 0000
Bootloader:
0x0BF9 0000
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