STM32F07xx单片机Systick配置

#include "main.h"

typedef uint32_t  u32;

typedef uint16_t u16;

typedef uint8_t  u8;

/*----------------------------------------------------------------------------

 * SystemCoreClockConfigure: configure SystemCoreClock using HSI

 *----------------------------------------------------------------------------*/

void SystemCoreClockConfigure(void)

{

  RCC->CR |= ((uint32_t)RCC_CR_HSION);                     // Enable HSI

RCC->CR &= ~((uint32_t)RCC_CR_HSEON);                    // Disable HSE

  while ((RCC->CR & RCC_CR_HSIRDY) == 0);                  // Wait for HSI Ready

  RCC->CFGR = RCC_CFGR_SW_HSI;                             // HSI is system clock

  while ((RCC->CFGR & RCC_CFGR_SWS) != RCC_CFGR_SWS_HSI);  // Wait for HSI used as system clock

  FLASH->ACR  = FLASH_ACR_PRFTBE;                          // Enable Prefetch Buffer

  FLASH->ACR |= FLASH_ACR_LATENCY;                         // Flash 1 wait state

  RCC->CFGR |= RCC_CFGR_HPRE_DIV1;                         // HCLK = SYSCLK

  RCC->CFGR |= RCC_CFGR_PPRE_DIV1;                         // PCLK = HCLK

  RCC->CR &= ~RCC_CR_PLLON;                                // Disable PLL

  //  PLL configuration:  = HSI/2 * 12 = 48 MHz

  RCC->CFGR &= ~(RCC_CFGR_PLLSRC | RCC_CFGR_PLLXTPRE | RCC_CFGR_PLLMUL);

  RCC->CFGR |=  (RCC_CFGR_PLLSRC_HSI_DIV2 | RCC_CFGR_PLLMUL12);

  RCC->CR |= RCC_CR_PLLON;                                 // Enable PLL

  while((RCC->CR & RCC_CR_PLLRDY) == 0) __NOP();           // Wait till PLL is ready

  RCC->CFGR &= ~RCC_CFGR_SW;                               // Select PLL as system clock source

  RCC->CFGR |=  RCC_CFGR_SW_PLL;

  while ((RCC->CFGR & RCC_CFGR_SWS) != RCC_CFGR_SWS_PLL);  // Wait till PLL is system clock src

}

void delay_us(u16 us)

{

SysTick->LOAD = us*8; //设置时间

SysTick->VAL = 0x00;        //清空计数器

SysTick->CTRL = 0x01;      //开始倒数

while((SysTick->CTRL & 0x10000) == 0);

SysTick->CTRL=0x00;       //关闭计数器

SysTick->VAL =0X00;       //清空计数器

}

void delay_ms(u16 ms)

{

SysTick->LOAD = 1000*8; //设置时间为1ms   

SysTick->VAL = 0x00;        //清空计数器

SysTick->CTRL = 0x01;      //开始倒数

while(ms)

{

while((SysTick->CTRL & 0x10000) == 0);

ms--;

}

SysTick->CTRL=0x00;       //关闭计数器

SysTick->VAL =0X00;       //清空计数器

}

void GPIO_test(void)

{                

   GPIO_InitTypeDef GPIO_InitStructure;

RCC_AHBPeriphClockCmd(RCC_AHBPeriph_GPIOC , ENABLE);

   //Latch Pin

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_6;

   GPIO_InitStructure.GPIO_Mode = GPIO_Mode_OUT;

   GPIO_InitStructure.GPIO_Speed = GPIO_Speed_10MHz;

   GPIO_Init(GPIOC, &GPIO_InitStructure);

}

int main(void)

{

  SystemCoreClockConfigure();

// SystemCoreClockUpdate();

USART_Config(115200);

GPIO_test();

  while (1)

  {

GPIO_SetBits(GPIOC,GPIO_Pin_6);

     delay_ms(2000);

GPIO_ResetBits(GPIOC,GPIO_Pin_6);

     delay_ms(2000);

  }

}