/* Configures the External High Speed oscillator (HSE). HSE can not be stopped if it is used directly or through the PLL as system clock.  */
void RCC_HSEConfig(uint32_t RCC_HSE)
/* Configures the External High Speed oscillator (HSE). HSE can not be stopped if it is used directly or through the PLL as system clock.  */
void RCC_HSEConfig(uint32_t RCC_HSE)
{
    assert_param(IS_RCC_HSE(RCC_HSE));
    RCC->CR &= CR_HSEON_Reset;
    RCC->CR &= CR_HSEBYP_Reset;
    switch(RCC_HSE)
    {
    case RCC_HSE_OFF:
        RCC->CR &= ~(CR_HSEBYP_Set | CR_HSEON_Set);
        break;   
		case RCC_HSE_ON:
        RCC->CR |= CR_HSEON_Set;
        break;
    case RCC_HSE_Bypass:
        RCC->CR |= CR_HSEBYP_Set | CR_HSEON_Set;
        break;
    default:
        break;
    }
}