Resolved! Why ACTVOSRDY bit and VOSRDY bit are always 0 after changing VOS bits in PWR registers?
These bits are always 0 and I can't change the voltage scaling of MCU (The code is stuck at both "while"s). The MCU P/N is STM32H743IIT6. The starting part of the code is:int main(void) { PWR->D3CR=0x0000C000; //changing voltage scaling to VOS1 ...