ST Nucleo-64 STM32WL3 Series User Manual page 14

7.4 Boot0
The NUCLEO-WL33CCx has a preprogrammed bootloader supporting the UART protocol with automatic baud
rate detection. The main features of the embedded bootloader are:
• Auto baud rate detection up to 1 Mbit/s
• Flash memory mass erase, section erase
• Flash memory programming
• Flash memory readout protections enable/disable
The preprogrammed bootloader is an application, which is stored in the internal ROM at manufacturing time by
STMicroelectronics. This application allows upgrading the flash memory device with a user application using a
serial communication channel (UART).
The bootloader is activated by forcing PA10 high during hardware reset, otherwise, the application in flash
memory is launched.
There are two possibilities on the NUCLEO-WL33CCx to force PA10 high:
• Solder an SB resistor on the R1 footprint of the MCU RF board. Note that this is not ideal, as the
STM32WL33CC does not boot on internal flash memory until the SB is OFF.
• Inserting a jumper between pins 5-7 of the ST morpho connector CN3, as shown in
Jumper CN3 [5-7]
UM3418 - Rev 1
Figure 9. Boot0 jumper location on ST morpho connector (CN3)
UM3418
Hardware layout and configuration
Figure 9.
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