Problem phenomenon: directly from the firmware soft reset to the bootloader update, the pcb board will restart
Cause of the problem: IWDG (Independent Watchdog) is enabled in the firmware program, and the dog is not fed during the firmware update, resulting in
When the count reaches 0, the watchdog resets again.
problem solved:
1. Because the independent watchdog cannot be turned off once it is turned on, either feed the dog in the bootloader or not start it.
2. Use the window watchdog instead, and close the watchdog before soft reset.