How to flash a bootloader onto the STM32WLE
STM32WLE5xx has 2x USART and 2x SPI bootloaders. You can find more or less complete list of system bootloaders per MCU family in AN2606
Which means, you do not have to program your own. You can use downloadable utilities with system one. It seems this bootloader does not require an access to boot pins, according to &quot;pattern 13&quot; in the same document.