在實際的項目開發過程中，常常遇到需要得到一段代碼的運行時間，通常的方法是用示波器來測量，這篇博文將用SysTick來實現精確測量程序運行的時間。STM32F4的內核定時器SysTick是一個24位的定時器，需要注意最大的測量時間。

1，開發環境

1，固件庫：STM32F4xx_DSP_StdPeriph_Lib_V1.8.0

2，編譯器：ARMCC V5.06

3，IDE：Keil uVision5

4，操作系統：Windows 10 專業版

2，程序源碼

MeasureTime.h文件

［cpp］ view plain copy/**

******************************************************************************

* @file MeasureTime.h

* @author XinLi

* @version v1.0

* @date 24-October-2017

* @brief Measure program run time module.

******************************************************************************

* @attention

*

* 《h2》《center》Copyright ? 2017 XinLi《/center》《/h2》

*

* This program is free software： you can redistribute it and/or modify

* it under the terms of the GNU General Public License as published by

* the Free Software Foundation， either version 3 of the License， or

* （at your option） any later version.

*

* This program is distributed in the hope that it will be useful，

* but WITHOUT ANY WARRANTY; without even the implied warranty of

* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the

* GNU General Public License for more details.

*

* You should have received a copy of the GNU General Public License

* along with this program. If not， see 《https://www.gnu.org/licenses/》。

*

******************************************************************************

*/

#ifndef __MEASURETIME_H

#define __MEASURETIME_H

#ifdef __cplusplus

extern “C” {

#endif

/* Header includes -----------------------------------------------------------*/

#include “stm32f4xx.h”

/* Macro definitions ---------------------------------------------------------*/

/* Type definitions ----------------------------------------------------------*/

/* Variable declarations -----------------------------------------------------*/

/* Variable definitions ------------------------------------------------------*/

/* Function declarations -----------------------------------------------------*/

/* Function definitions ------------------------------------------------------*/

/**

* @brief Start measure time.

* @param None.

* @return None.

*/

__STATIC_INLINE void MeasureTimeStart（void）

{

SysTick-》CTRL |= SysTick_CLKSource_HCLK; /* Set the SysTick clock source. */

SysTick-》LOAD = 0xFFFFFF; /* Time load （SysTick-》 LOAD is 24bit）。 */

SysTick-》VAL = 0xFFFFFF; /* Empty the counter value. */

SysTick-》CTRL |= SysTick_CTRL_ENABLE_Msk; /* Start the countdown. */

__nop（）; /* Waiting for a machine cycle. */

}

/**

* @brief Stop measure time.

* @param ［in］ clock： System clock frequency（unit： MHz）。

* @return Program run time（unit： us）。

*/

__STATIC_INLINE double MeasureTimeStop（uint32_t clock）

{

uint32_t count = SysTick-》VAL; /* Read the counter value. */

SysTick-》CTRL &= ~SysTick_CTRL_ENABLE_Msk; /* Close counter. */

double time = 0.0;

if（clock 》 0）

{

time = （double）（0xFFFFFF - count） / （double）clock; /* Calculate program run time. */

}

return time;

}

#ifdef __cplusplus

}

#endif

#endif /* __MEASURETIME_H */

main.c文件

［cpp］ view plain copy/**

******************************************************************************

* @file main.c

* @author XinLi

* @version v1.0

* @date 24-October-2017

* @brief Main program body.

******************************************************************************

* @attention

*

* 《h2》《center》Copyright ? 2017 XinLi《/center》《/h2》

*

* This program is free software： you can redistribute it and/or modify

* it under the terms of the GNU General Public License as published by

* the Free Software Foundation， either version 3 of the License， or

* （at your option） any later version.

*

* This program is distributed in the hope that it will be useful，

* but WITHOUT ANY WARRANTY; without even the implied warranty of

* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the

* GNU General Public License for more details.

*

* You should have received a copy of the GNU General Public License

* along with this program. If not， see 《https://www.gnu.org/licenses/》。

*

******************************************************************************

*/

/* Header includes -----------------------------------------------------------*/

#include “main.h”

#include “MeasureTime.h”

/* Macro definitions ---------------------------------------------------------*/

/* Type definitions ----------------------------------------------------------*/

/* Variable declarations -----------------------------------------------------*/

/* Variable definitions ------------------------------------------------------*/

static __IO double runTime = 0.0;

/* Function declarations -----------------------------------------------------*/

__STATIC_INLINE void delay_1us（void）;

/* Function definitions ------------------------------------------------------*/

/**

* @brief Main program.

* @param None.

* @return None.

*/

int main（void）

{

for（;;）

{

MeasureTimeStart（）;

delay_1us（）;

runTime = MeasureTimeStop（84）;

}

}

/**

* @brief One microsecond delay.

* @param None.

* @return None.

*/

__STATIC_INLINE void delay_1us（void）

{

__nop（）; __nop（）; __nop（）; __nop（）; __nop（）; __nop（）; __nop（）; __nop（）; __nop（）; __nop（）;

__nop（）; __nop（）; __nop（）; __nop（）; __nop（）; __nop（）; __nop（）; __nop（）; __nop（）; __nop（）;

__nop（）; __nop（）; __nop（）; __nop（）; __nop（）; __nop（）; __nop（）; __nop（）; __nop（）; __nop（）;

__nop（）; __nop（）; __nop（）; __nop（）; __nop（）; __nop（）; __nop（）; __nop（）; __nop（）; __nop（）;

__nop（）; __nop（）; __nop（）; __nop（）; __nop（）; __nop（）; __nop（）; __nop（）; __nop（）; __nop（）;

__nop（）; __nop（）; __nop（）; __nop（）; __nop（）; __nop（）; __nop（）; __nop（）; __nop（）; __nop（）;

__nop（）; __nop（）; __nop（）; __nop（）; __nop（）; __nop（）; __nop（）; __nop（）; __nop（）; __nop（）;

__nop（）; __nop（）; __nop（）; __nop（）; __nop（）; __nop（）; __nop（）; __nop（）; __nop（）; __nop（）;

__nop（）; __nop（）; __nop（）; __nop（）;

}