18 tim3外部计数器 实现

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附件: 18tim3外部计数器.rar  

  设置tim3 为外部计数器模式，从信号发生器中输入 100hz 的方波， tim3计数器中每100个方波产生一个中断

void test(void)
{
    GPIO_InitTypeDef GPIO_InitStructure;
    NVIC_InitTypeDef NVIC_InitStructure;
    TIM_TimeBaseInitTypeDef      TIM_TimeBaseStructure;

    RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA,ENABLE);

    GPIO_InitStructure.GPIO_Pin =  GPIO_Pin_7;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_2MHz;
    GPIO_Init(GPIOA, &GPIO_InitStructure);

/************************************************/


    RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE); //TIM3时钟配置选择
    //TIM3输出初始化
    TIM_DeInit(TIM3); //TIM3 ch2 pin17 pa7

    TIM_TimeBaseStructure.TIM_Period = 99; //计数值=100-1
    TIM_TimeBaseStructure.TIM_Prescaler = 0; //预分频
    TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1; //时钟分割
    TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Down; //模式
    TIM_TimeBaseInit(TIM3, &TIM_TimeBaseStructure); //基本初始化

    TIM_SetCounter(TIM3, 99); //设置 TIM3 计数器寄存器值
    TIM_ARRPreloadConfig(TIM3, ENABLE); //设置 TIMx 自动重装载寄存器值
    TIM_SelectInputTrigger(TIM3, TIM_TS_TI2FP2);
    TIM_SelectSlaveMode(TIM3, TIM_SlaveMode_External1);

    //TIM3通道的捕捉初始化
    TIM_SetCompare2(TIM3, 99);
    TIM_Cmd(TIM3, ENABLE); //启动TIM3
    TIM_ClearFlag(TIM3, TIM_IT_CC2);
    TIM_ITConfig(TIM3, TIM_IT_CC2, ENABLE); //打开中断


//#if 0
#ifdef  VECT_TAB_RAM
    /* Set the Vector Table base location at 0x20000000 */
    NVIC_SetVectorTable(NVIC_VectTab_RAM, 0x0);
#else  /* VECT_TAB_FLASH  */
    /* Set the Vector Table base location at 0x08000000 */
    NVIC_SetVectorTable(NVIC_VectTab_FLASH, 0x0);
#endif
//#endif

    NVIC_PriorityGroupConfig(NVIC_PriorityGroup_2);//抢占式优先级别, 无抢占优先级


    NVIC_InitStructure.NVIC_IRQChannel = TIM3_IRQn; //
    NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 1; //抢占优先级0
    NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0; //响应优先级0
    NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE; //允许中断
    NVIC_Init(&NVIC_InitStructure);    //写入设置
}