定时器1中断溢出时间的计算

秋夏之叶 · 发表于 2014-11-18 14:17:01

各位大神，我将定时器1进行初始化，按STM32系统时钟树来看，TIM1入口时钟应该为72Mhz，那么根据Tout=((arr+1)*(psc+1))/Tcllk公式计算出的中断时间为500ms才对，但实际上不是的，这是为什么呢？
void TIM1_Init(u16 arr,u16 psc)
{
        TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
        NVIC_InitTypeDef NVIC_InitStructure;

        RCC_APB2PeriphClockCmd(RCC_APB2Periph_TIM1, ENABLE); //时钟使能

        //定时器TIM1初始化
        TIM_TimeBaseStructure.TIM_Period = arr;
        TIM_TimeBaseStructure.TIM_Prescaler =psc;
        TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1;
        TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
        TIM_TimeBaseInit(TIM1, &TIM_TimeBaseStructure);

        TIM_ITConfig(TIM1,TIM_IT_Update,ENABLE );

        //中断优先级NVIC设置
        NVIC_InitStructure.NVIC_IRQChannel = TIM1_UP_IRQn;
        NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0X02;
        NVIC_InitStructure.NVIC_IRQChannelSubPriority =0X03;
        NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
        NVIC_Init(&NVIC_InitStructure); //初始化NVIC寄存器

        TIM_Cmd(TIM1, ENABLE);

}
//TIM1中断
void TIM1_UP_IRQHandler(void)
{
        if (TIM_GetITStatus(TIM1,TIM_IT_Update) != RESET) //检查TIM1更新中断发生与否
        {
                led1=!led1;
        }
TIM_ClearITPendingBit(TIM1,TIM_IT_Update ); //清除TIMx更新中断标志
}

主函数中初始化：
TIM1_Init(4999,7199);