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7.10 Reset sources
The reset signal of the STM32U575AII6Q on the STM32U575I-EV Evaluation board is active low.
Sources of reset are:
•
B2 RESET button (black button)
• CN17 JTAG connector, CN12 TRACE connector, CN18 STDC14 connector, and CN13 TAG connector (reset
from debug tools)
• Through CN10 extension connector pin 27 (reset from daughterboard)
• U26 embedded STLINK-V3E MCU
• JP34 OFF optional external RS-232 interface
7.11 RSS/bootloader
7.11.1 Description
The bootloader is located in the system memory, programmed by ST during production. It is used to reprogram
the Flash memory by using USART, I
2
C, SPI, CAN FD, or USB FS in device mode through the DFU (device
firmware upgrade). The bootloader is available on all devices. Refer to the application note STM32 microcontroller
system memory boot mode ( AN2606 ) for more details.
The root secure services (RSS) are embedded in a Flash area named secure information block, programmed
during ST production. For example, it enables secure firmware installation (SFI) thanks to the RSS extension
firmware (RSSe SFI). This feature allows customers to protect the confidentiality of the firmware to be provisioned
into the STM32 when production is sub
‑
contracted to an untrusted third party. The RSS is available on all devices,
after enabling the TrustZone
®
through the TZEN option bit.
The bootloader version can be identified by reading the bootloader ID at the address
0x0BF97FFE
.
7.11.2 Boot from RSS
The BOOT0 value may come from the PH3_BOOT0 pin, connected to the boot switch SW1, or from an option bit
depending on the value of a user option bit.
Table 19 describes the hardware configuration of the SW1 switch for the Boot mode.
Table 19. SW1 boot selection switch
I/O Switch Setting
(1)
Comment
PH3 SW1
BOOT0 = 0
(SW1 down) BOOT0 line is tied LOW. STM32U575AII6Q boot address defined by
the user option bytes NSBOOTADD0 or SECBOOTADD0 according to
TrustZone
®
setting.
BOOT0 = 1
(SW1 up)
BOOT0 line is tied HIGH. STM32U575AII6Q boot address defined by the user
option bytes NSBOOTADD1 or RSS according to TrustZone
®
setting.
1. The default configuration is shown in bold.
BOOT0 line can also be driven by external equipment connected to the CN6 RS-232 connector pin 6. In this case,
the jumper JP3 must be ON.
STM32U575I-EV
Reset sources
UM2854 - Rev 1
page 36/105