/* Enables or disables the PLL. The PLL can not be disabled if it is used as system clock.  */
void RCC_PLLCmd(FunctionalState state)
/* Enables or disables the PLL. The PLL can not be disabled if it is used as system clock.  */
void RCC_PLLCmd(FunctionalState state)
{
    MODIFY_REG(RCC->CR, RCC_CR_PLLON, (state << RCC_CR_PLLON_Pos));
}