STM32F4(用SysTick实现Delay函数)[通俗易懂]

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STM32F4(用SysTick实现Delay函数)

PS：博文不再更新，后续更新会在GitHub仓库进行。

1，开发环境

      1，适用芯片：STM32F4全部芯片

      2，固件库：STM32F4xx_DSP_StdPeriph_Lib_V1.8.0

      3，IDE：MDK517

2，驱动源码

      Delay.h文件

/****************************************************************
 * Copyright (C) 2016, XinLi, all right reserved.
 * File name:    Delay.h
 * Date:         2016.03.22
 * Description:  Delay Driver
*****************************************************************/

#ifndef __DELAY_H
#define __DELAY_H

/****************************************************************
 *                        Header include
*****************************************************************/
#include "stm32f4xx.h"

/****************************************************************
 *                       Macro definition
*****************************************************************/


/****************************************************************
 *                       Type definition
*****************************************************************/


/****************************************************************
 *                     Structure definition
*****************************************************************/



#ifdef __cplusplus
 extern "C" {
#endif  /* __cplusplus */

/****************************************************************
 *                     Variable declaration
*****************************************************************/


/****************************************************************
 *                     Function declaration
*****************************************************************/
void Delay_us(uint64_t nus);
void Delay_ms(uint64_t nms);
void Delay_s(uint64_t ns);

#ifdef __cplusplus
}
#endif  /* __cplusplus */

#endif	/* __DELAY_H */

      Delay.c文件

/****************************************************************
 * Copyright (C) 2016, XinLi, all right reserved.
 * File name:    Delay.c
 * Date:         2016.03.22
 * Description:  Delay Driver
*****************************************************************/

/****************************************************************
 *                        Header include
*****************************************************************/
#include "Delay.h"

/****************************************************************
 *                       Global variables
*****************************************************************/


/****************************************************************
 *                     Function declaration
*****************************************************************/
static void Delay_Init(void);

/****************************************************************
 *                     Function definition
*****************************************************************/

/****************************************************************
 * Function:    Delay_Init
 * Description: Delay Configuration.
 * Input:
 * Output:
 * Return:
*****************************************************************/
static void Delay_Init(void)
{
  static uint8_t first = 0;
  
  if(first == 0)
  {
    first = 1;
    
    SysTick_CLKSourceConfig(SysTick_CLKSource_HCLK_Div8);
    SysTick->CTRL &= ~SysTick_CTRL_ENABLE_Msk;  /* Disability SysTick counter */
  }
}

/****************************************************************
 * Function:    Delay_us
 * Description: Microsecond delay.
 * Input:       nus
 * Output:
 * Return:
*****************************************************************/
void Delay_us(uint64_t nus)
{
  uint32_t temp = 0;
  uint64_t nms = 0;
  
  Delay_Init();
  
  if(nus == 0)
  {
    return;
  }
  
  nms = nus / 1000;
  nus = nus % 1000;
  
  if(nms > 0)
  {
    Delay_ms(nms);
  }

  if(nus > 0)
  {
    SysTick->LOAD = SystemCoreClock / 8000000 * nus;  /* Time load (SysTick-> LOAD is 24bit) */
    SysTick->VAL = 0x000000;                          /* Empty counter */
    SysTick->CTRL |= SysTick_CTRL_ENABLE_Msk;         /* Start the countdown */

    do
    {
      temp = SysTick->CTRL;
    }
    while(temp&0x01 && !(temp&(1<<16)));        /* Wait time is reached */

    SysTick->CTRL &= ~SysTick_CTRL_ENABLE_Msk;  /* Close Counter */
    SysTick->VAL = 0x000000;                    /* Empty counter */
  }
}

/****************************************************************
 * Function:    Delay_ms
 * Description: Millisecond delay.
 * Input:       nms
 * Output:
 * Return:
*****************************************************************/
void Delay_ms(uint64_t nms)
{
  uint32_t temp = 0;
  
  Delay_Init();
  
  if(nms == 0)
  {
    return;
  }
  
  while(nms > 500)
  {
    SysTick->LOAD = SystemCoreClock / 8000 * 500; /* Time load (SysTick-> LOAD is 24bit) */
    SysTick->VAL = 0x000000;                      /* Empty counter */
    SysTick->CTRL |= SysTick_CTRL_ENABLE_Msk;     /* Start the countdown */

    do
    {
      temp = SysTick->CTRL;
    }
    while(temp&0x01 && !(temp&(1<<16)));        /* Wait time is reached */

    SysTick->CTRL &= ~SysTick_CTRL_ENABLE_Msk;  /* Close Counter */
    SysTick->VAL = 0x000000;                    /* Empty counter */
    
    nms -= 500;
  }
  
  SysTick->LOAD = SystemCoreClock / 8000 * nms; /* Time load (SysTick-> LOAD is 24bit) */
  SysTick->VAL = 0x000000;                      /* Empty counter */
  SysTick->CTRL |= SysTick_CTRL_ENABLE_Msk;     /* Start the countdown */

  do
  {
    temp = SysTick->CTRL;
  }
  while(temp&0x01 && !(temp&(1<<16)));        /* Wait time is reached */

  SysTick->CTRL &= ~SysTick_CTRL_ENABLE_Msk;  /* Close Counter */
  SysTick->VAL = 0x000000;                    /* Empty counter */
}

/****************************************************************
 * Function:    Delay_s
 * Description: Second delay.
 * Input:       ns
 * Output:
 * Return:
*****************************************************************/
void Delay_s(uint64_t ns)
{
  while(ns > 0)
  {
    Delay_ms(1000);
    ns--;
  }
}