非RTOS 的delay功能实现 时钟使用SystemInit()初始化(3.5版本库函数)

uint32_t SystemCoreClock         = SYSCLK_FREQ_72MHz;        /*!< System Clock Frequency (Core Clock) */

#include "delay.h"

static uint16_t factor_us;    //根据系统时钟，延时1uS的计数值
static uint16_t factor_ms; //根据系统时钟，延时1mS的计数值


//---------------------------------------------------------------------------
//函数功能:延时函数初始化
//描述:
//    1.SYSCLOCK：系统时钟
//    2.
// 执行周期:
//日期:2017/10/22 11:53:11
//---------------------------------------------------------------------------
void DelayInit(void)
{
    SysTick->CTRL &= 0xfffffffb;             //清除BIT2 ，0 外部时钟源(STCLK) 1 内核时钟(FCLK)
    factor_us = SystemCoreClock/8000000;    //系统时钟8分频
    factor_ms = factor_us*1000;            
}

//---------------------------------------------------------------------------
//函数功能:延时函数微秒级
//描述:
//    1.SYSCLOCK：系统时钟
//    2.
// 执行周期:
//日期:2017/10/22 11:53:11
//---------------------------------------------------------------------------
void delay_us(uint16_t delay_us_cnt)
{
    uint32_t SysTick_CTRL_buf_us;
    SysTick->LOAD = delay_us_cnt * factor_us; //装载重载计数器初始值    
    SysTick->VAL = 0;            //清零计数器初始值    
    SysTick->CTRL |= SysTick_CTRL_ENABLE_Msk;        //使能systick 定时器
    //开始计时
    do
    {
        SysTick_CTRL_buf_us = SysTick->CTRL ;
    }while( (SysTick_CTRL_buf_us&0x01) && ( !(SysTick_CTRL_buf_us&(1<<16)) ) );
    SysTick->CTRL &= ~SysTick_CTRL_ENABLE_Msk;    //关闭计数器
    SysTick->VAL = 0;                                                   //清空计数器     
}

//---------------------------------------------------------------------------
//函数功能:延时函数微秒级
//描述:
//    1.SYSCLOCK：系统时钟
//    2.
// 执行周期:
//日期:2017/10/22 11:53:11
//---------------------------------------------------------------------------
void delay_ms(uint16_t delay_ms_cnt)
{
    uint32_t SysTick_CTRL_buf_ms;
    SysTick->LOAD = delay_ms_cnt * factor_ms; //装载重载计数器初始值    
    SysTick->VAL = 0;            //清零计数器初始值    
    SysTick->CTRL |= SysTick_CTRL_ENABLE_Msk;        //使能systick 定时器
    //开始计时
    do
    {
        SysTick_CTRL_buf_ms = SysTick->CTRL ;
    }while( (SysTick_CTRL_buf_ms&0x01) && ( !(SysTick_CTRL_buf_ms&(1<<16)) ) );
    SysTick->CTRL &= ~SysTick_CTRL_ENABLE_Msk;    //关闭计数器
    SysTick->VAL = 0;                                                   //清空计数器     
}

---

 SysTick的库函数部分,来自Core_cm3.h

/** @addtogroup CMSIS_CM3_SysTick CMSIS CM3 SysTick
  memory mapped structure for SysTick
  @{
 */
typedef struct
{
  __IO uint32_t CTRL;                         /*!< Offset: 0x00  SysTick Control and Status Register *///控制与状态寄存器
  __IO uint32_t LOAD;                         /*!< Offset: 0x04  SysTick Reload Value Register       *///重装值寄存器
  __IO uint32_t VAL;                          /*!< Offset: 0x08  SysTick Current Value Register      *///当前值寄存器
  __I  uint32_t CALIB;                        /*!< Offset: 0x0C  SysTick Calibration Register        *///校准寄存器
} SysTick_Type;

/* SysTick Control / Status Register Definitions */
#define SysTick_CTRL_COUNTFLAG_Pos         16                                             /*!< SysTick CTRL: COUNTFLAG Position */
#define SysTick_CTRL_COUNTFLAG_Msk         (1ul << SysTick_CTRL_COUNTFLAG_Pos)            /*!< SysTick CTRL: COUNTFLAG Mask */

#define SysTick_CTRL_CLKSOURCE_Pos          2                                             /*!< SysTick CTRL: CLKSOURCE Position */
#define SysTick_CTRL_CLKSOURCE_Msk         (1ul << SysTick_CTRL_CLKSOURCE_Pos)            /*!< SysTick CTRL: CLKSOURCE Mask */

#define SysTick_CTRL_TICKINT_Pos            1                                             /*!< SysTick CTRL: TICKINT Position */
#define SysTick_CTRL_TICKINT_Msk           (1ul << SysTick_CTRL_TICKINT_Pos)              /*!< SysTick CTRL: TICKINT Mask */

#define SysTick_CTRL_ENABLE_Pos             0                                             /*!< SysTick CTRL: ENABLE Position */
#define SysTick_CTRL_ENABLE_Msk            (1ul << SysTick_CTRL_ENABLE_Pos)               /*!< SysTick CTRL: ENABLE Mask */

/* SysTick Reload Register Definitions */
#define SysTick_LOAD_RELOAD_Pos             0                                             /*!< SysTick LOAD: RELOAD Position */
#define SysTick_LOAD_RELOAD_Msk            (0xFFFFFFul << SysTick_LOAD_RELOAD_Pos)        /*!< SysTick LOAD: RELOAD Mask */ //最大装载值24字节

/* SysTick Current Register Definitions */
#define SysTick_VAL_CURRENT_Pos             0                                             /*!< SysTick VAL: CURRENT Position */
#define SysTick_VAL_CURRENT_Msk            (0xFFFFFFul << SysTick_VAL_CURRENT_Pos)        /*!< SysTick VAL: CURRENT Mask */ //最大装载值24字节

/* SysTick Calibration Register Definitions */
#define SysTick_CALIB_NOREF_Pos            31                                             /*!< SysTick CALIB: NOREF Position */
#define SysTick_CALIB_NOREF_Msk            (1ul << SysTick_CALIB_NOREF_Pos)               /*!< SysTick CALIB: NOREF Mask */

#define SysTick_CALIB_SKEW_Pos             30                                             /*!< SysTick CALIB: SKEW Position */
#define SysTick_CALIB_SKEW_Msk             (1ul << SysTick_CALIB_SKEW_Pos)                /*!< SysTick CALIB: SKEW Mask */

#define SysTick_CALIB_TENMS_Pos             0                                             /*!< SysTick CALIB: TENMS Position */
#define SysTick_CALIB_TENMS_Msk            (0xFFFFFFul << SysTick_VAL_CURRENT_Pos)        /*!< SysTick CALIB: TENMS Mask */
/*@}*/ /* end of group CMSIS_CM3_SysTick */

SysTick寄存器地址定义

#define SCS_BASE            (0xE000E000)                              /*!< System Control Space Base Address */
#define SysTick_BASE        (SCS_BASE +  0x0010)                      /*!< SysTick Base Address              */
#define SysTick             ((SysTick_Type *)       SysTick_BASE)     /*!< SysTick configuration struct      */

SysTick function 函数

/* ##################################    SysTick function  ############################################ */

#if (!defined (__Vendor_SysTickConfig)) || (__Vendor_SysTickConfig == 0)

/**
 * @brief  Initialize and start the SysTick counter and its interrupt.
 *
 * @param   ticks   number of ticks between two interrupts
 * @return  1 = failed, 0 = successful
 *
 * Initialise the system tick timer and its interrupt and start the
 * system tick timer / counter in free running mode to generate 
 * periodical interrupts.
 */
static __INLINE uint32_t SysTick_Config(uint32_t ticks)
{ 
  if (ticks > SysTick_LOAD_RELOAD_Msk)  return (1);            /* Reload value impossible */
                                                               
  SysTick->LOAD  = (ticks & SysTick_LOAD_RELOAD_Msk) - 1;      /* set reload register */
  NVIC_SetPriority (SysTick_IRQn, (1<<__NVIC_PRIO_BITS) - 1);  /* set Priority for Cortex-M0 System Interrupts */
  SysTick->VAL   = 0;                                          /* Load the SysTick Counter Value */
  SysTick->CTRL  = SysTick_CTRL_CLKSOURCE_Msk | 
                   SysTick_CTRL_TICKINT_Msk   | 
                   SysTick_CTRL_ENABLE_Msk;                    /* Enable SysTick IRQ and SysTick Timer */
  return (0);                                                  /* Function successful */
}

#endif

---

MISC.h宏定义时钟来源及分频

#define SysTick_CLKSource_HCLK_Div8    ((uint32_t)0xFFFFFFFB)
#define SysTick_CLKSource_HCLK         ((uint32_t)0x00000004)
#define IS_SYSTICK_CLK_SOURCE(SOURCE) (((SOURCE) == SysTick_CLKSource_HCLK) || \
                                       ((SOURCE) == SysTick_CLKSource_HCLK_Div8))

 

Systick的时钟来源有两个:HCLK 或者HCLK的8分频

 

---

 

SysTick 中断

中断向量定义在startup_stm32f10x_hd.s文件 line77

DCD     SysTick_Handler            ; SysTick Handler

中断函数定义在stm32f10x_it.c lin135

/**
  * @brief  This function handles SysTick Handler.
  * @param  None
  * @retval None
  */
void SysTick_Handler(void)
{
}