/* SystemFrequency / 1000 1ms中斷一次

* SystemFrequency / 100000 10us中斷一次

* SystemFrequency / 1000000 1us中斷一次

*/

#define SYSTICKPERIOD 0.000001

#define SYSTICKFREQUENCY (1/SYSTICKPERIOD)

/**

* @brief 定時器2的初始化,，定時周期1ms

* @param 無

* @retval 無

*/

void TIM2_Init(void)

{

TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;

/*AHB = 72MHz,RCC_CFGR的PPRE1 = 2，所以APB1 = 36MHz,TIM2CLK = APB1*2 = 72MHz */

RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);

/* Time base configuration */

TIM_TimeBaseStructure.TIM_Period = 999;

TIM_TimeBaseStructure.TIM_Prescaler = SystemCoreClock/SYSTICKFREQUENCY -1;

TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;

TIM_TimeBaseInit(TIM2, &TIM_TimeBaseStructure);

TIM_ARRPreloadConfig(TIM2, ENABLE);

/* 設(shè)置更新請求源只在計數(shù)器上溢或下溢時產(chǎn)生中斷 */

TIM_UpdateRequestConfig(TIM2,TIM_UpdateSource_Global);

TIM_ClearFlag(TIM2, TIM_FLAG_Update);

}

/**

* @brief ms延時程序,1ms為一個單位

* @param

* @arg nTime: Delay_ms( 10 ) 則實現(xiàn)的延時為 10 * 1ms = 10ms

* @retval 無

*/

void Delay_ms(__IO uint32_t nTime)

{

/* 清零計數(shù)器并使能滴答定時器 */

TIM2->CNT = 0;

TIM_Cmd(TIM2, ENABLE);

for( ; nTime > 0 ; nTime--)

{

/* 等待一個延時單位的結(jié)束 */

while(TIM_GetFlagStatus(TIM2, TIM_FLAG_Update) != SET);

TIM_ClearFlag(TIM2, TIM_FLAG_Update);

}

TIM_Cmd(TIM2, DISABLE);

}