Peripheral_clock

//Includes
#include <stdint.h>                                             //system header
#include "stm32f407xx.h"                  // Non system headers use quotes

//main
    int main(void)
    {
        ADC_TypeDef *pADC;          //set the Type as a pointer
        RCC_TypeDef *pRCC;
        pADC = ADC1;                        //make the pointer address the same as ADC1
        pRCC = RCC;

        //enable clock
        pRCC->APB2ENR = pRCC->APB2ENR | (1 << 8);           //set the 9th bit (bit8) to 1
                                                                                                    //or '1 shifted by 8' (starting from bit position 0)
        //access the peripheral register
        pADC->CR1 = 0x55;                               // -> is 'Member Access' and is used to access the members of pADC(ADC1)
                                                                        //CR! is the 'Control Register 1'
        return 0;
    }