Hello there!
I would like to ask for help from those who know this MCU family about the system memory bootloader. As specified in the AN2606 Rev64 document, section 41.2, after the System Reset the microcontroller checks the value of the nDBANK and nDBOOT flags. If these are both equal to zero, it will check the value of the BOOT0 pin, otherwise it will run the System Memory bootloader.
Looking at the RM0410 Rev5 document, it seems that the reset value of these flags is 1, making the start of this bootloader inevitable, at least the very first time, with MCU in factory state, and before to have the possibility to toggle the flags to 0.
We plan to load a custom bootloader through JTAG, but we don't want this default bootloader to start, as we would like to be free to use the MCU pinout. What would happen if a peripheral of a certain type was connected to one of the pins that the System Memory Bootloader configures and during the first flash of the code the JTAG did not take control in time, before the embedded bootloader starts? There could be a possibility of damaging our hardware or the microcontroller itself. I wanted to know if some expert or someone who has already faced the problem had found some solution, or could tell me if we have misinterpreted the information written in the Application Notes above. Thank you very much for the support!
Andrea Moreschi
