STM32 定时器定时时间的计算

假设系统时钟是72Mhz，TIM1 是由PCLK2 （72MHz）得到，TIM2-7是由 PCLK1得到关键是设定 时钟预分频数，自动重装载寄存器周期的值/*每1秒发生一次更新事件(进入中断服务程序)。RCC_Configuration()的SystemInit()的RCC->CFGR |= (uint32_t)RCC_CFGR_PPRE1_DIV2表明TIM3CLK为72MHz。因此，每次进入中断服务程序间隔时间为： ((1+TIM_Prescaler )/72M)*(1+TIM_Period )=((1+7199)/72M)*(1+9999)=1秒。定时器的基本设置如下：

1、TIM_TimeBaseStructure.TIM_Prescaler = 7199;//时钟预分频数   例如 ：时钟频率=72/(时钟预分频+1)。 

   2、TIM_TimeBaseStructure.TIM_Period = 9999; // 自动重装载寄存器周期的值(定时时间)累计 0xFFFF个频率后产生个更新或者中断(也是说定时时间到)。

   3、TIM_TimeBaseStructure.TIM_CounterMode=TIM1_CounterMode_Up; //定时器模式向上计数。

   4、 TIM_TimeBaseStructure.TIM_ClockDivision = 0x0; //时间分割值。 

   5、 TIM_TimeBaseInit(TIM2, &TIM_TimeBaseStructure);//初始化定时器2。

   6、  TIM_ITConfig(TIM2, TIM_IT_Update, ENABLE);  //打开中断溢出中断。  

   7、 TIM_Cmd(TIM2, ENABLE);//打开定时器或者：

TIM_TimeBaseStructure.TIM_Prescaler = 35999;//分频35999，72M/

(35999+1)/2=1Hz  1秒中断溢出一次。

   8、 TIM_TimeBaseStructure.TIM_Period = 2000; //计数值2000 ((1+TIM_Prescaler )/72M)*(1+TIM_Period )=((1+35999)/72M)*(1+2000)=1秒。

 

通用定时器实现简单定时功能

 

以TIME3为例作为说明，简单定时器的配置如下：

void TIM3_Config(void)

{

    TIM_TimeBaseInitTypeDef  TIM_TimeBaseStructure;

    TIM_DeInit(TIM3);                              //复位TIM2定时器

    /* TIM2 clock enable [TIM2定时器允许]*/

    RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE);

    /* TIM2 configuration */

    TIM_TimeBaseStructure.TIM_Period = 49;          // 0.05s定时       

    TIM_TimeBaseStructure.TIM_Prescaler = 35999;    // 分频36000       

    TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1;  // 时钟分割  

    TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;  //计数方向向上计数

    TIM_TimeBaseInit(TIM3, &TIM_TimeBaseStructure);

    /* Clear TIM2 update pending flag[清除TIM2溢出中断标志] */

    TIM_ClearFlag(TIM3, TIM_FLAG_Update);

    /* Enable TIM2 Update interrupt [TIM2溢出中断允许]*/

    TIM_ITConfig(TIM3, TIM_IT_Update, ENABLE);  

    /* TIM2 enable counter [允许tim2计数]*/

    TIM_Cmd(TIM3, ENABLE);

}

 

通用定时器实现外部脉冲计数功能（对外部时间计数）

 

以TIME2为例作为说明，提供一个小程序以供参考（只提供主程序，不提供其它的基础配置）：

int main(void)

{

     #ifdef DEBUG

     debug();

     #endif

     int i_Loop;

  int n_Counter;

  RCC_Configuration();   // System Clocks Configuration

  NVIC_Configuration();  // NVIC configuration

  GPIO_Configuration();  // Configure the GPIO ports

     USART_InitStructure.USART_BaudRate = 115200;

     USART_InitStructure.USART_WordLength = USART_WordLength_8b;

     USART_InitStructure.USART_StopBits = USART_StopBits_1;

     USART_InitStructure.USART_Parity = USART_Parity_No ;

    USART_InitStructure.USART_HardwareFlowControl=USART_HardwareFlowControl_None;

     USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;

     USART_InitStructure.USART_Clock = USART_Clock_Disable;

     USART_InitStructure.USART_CPOL = USART_CPOL_Low;

     USART_InitStructure.USART_CPHA = USART_CPHA_2Edge;

     USART_InitStructure.USART_LastBit = USART_LastBit_Disable;

     /* Configure the USARTx */

     USART_Init(USART1, &USART_InitStructure);

     /* Enable the USARTx */

     USART_Cmd(USART1, ENABLE)

TIM_TimeBaseStructure.TIM_Period = 0xFFFF;

TIM_TimeBaseStructure.TIM_Prescaler = 0x00;

TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1;

TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;

TIM_TimeBaseInit(TIM2, &TIM_TimeBaseStructure); // Time base configuration

TIM_ETRClockMode2Config(TIM2, TIM_ExtTRGPSC_OFF, TIM_ExtTRGPolarity_NonInverted, 0);

TIM_SetCounter(TIM2, 0);

TIM_Cmd(TIM2, ENABLE);

for(i_Loop = 0; i_Loop < 1000; i_Loop ++)

   {

        GPIO_SetBits(GPIOC, GPIO_Pin_6);

        Delay(100);

        GPIO_ResetBits(GPIOC, GPIO_Pin_6);

        Delay(100);

 }

n_Counter = TIM_GetCounter(TIM2);

    while(USART_GetFlagStatus(USART1, USART_FLAG_TXE) == RESET);

    printf("检测到的脉冲个数为：%d\n",n_Counter);

    while (1) {

              }

}