void RCC_Config(){

ErrorStatus HSEStartUpStatus;

RCC_DeInit();
RCC_HSEConfig(RCC_HSE_ON);
HSEStartUpStatus = RCC_WaitForHSEStartUp();
if(HSEStartUpStatus == SUCCESS){
FLASH_PrefetchBufferCmd(ENABLE);
FLASH_SetLatency(FLASH_Latency_4);
RCC_HCLKConfig(RCC_SYSCLK_Div1);
RCC_PCLK2Config(RCC_HCLK_Div1);
RCC_PCLK1Config(RCC_HCLK_Div1);
RCC_PLLConfig(RCC_PLLSource_HSE,8,360,2,7);
RCC_PLLCmd(ENABLE);
while( RCC_GetFlagStatus(RCC_FLAG_PLLRDY) == RESET);
RCC_SYSCLKConfig(RCC_SYSCLKSource_PLLCLK);
SystemCoreClockUpdate();
while(RCC_GetSYSCLKSource() !=0x08);