STM32F103 TIM1比较输出不能输出高频率？

1万 · 2021-10-9 23:35

我的目的是想利用定时器1比较输出500Khz的高低电平信号，也就是用定时器1产生500Khz的中断，
先试用500hz的程序如下：
void timer_init(void)
{
      RCC->APB2ENR |= 1 << 11;
      TIM1->ARR = 0xFFFF;//
      TIM1->PSC = 71;//CPU工作频率72M，预分频72000000/(71+1)=1M，所以定时器1工作频率为1M
      TIM1->CCR1 = 0xFFFF;
      TIM1->RCR = 0x00;
      TIM1->DIER = 0x03;//开启比较中断
      TIM1->BDTR = 0x8000;
      TIM1->CR1 = 0x81;定时器1使能
      nvic_init(2,2,TIM1_CC_IRQn,2);
}

void TIM1_CC_IRQHandler(void) //定时器1中断
{
      u16 temp;

      if (TIM1->SR & 0x0002)
      {
            TIM1->SR &= 0xFFFD;
            LED0 = !LED0;利用LED的高低电平测量验证
            temp = TIM1->CCR1;
            TIM1->CCR1 = temp + 2000; //  1M/2000=500HZ，用示波器测量是很标准的高电平2ms，低电平也是2ms
      }
}

下面是500Khz的程序如下：
void timer_init(void)
{
      RCC->APB2ENR |= 1 << 11;
      TIM1->ARR = 0xFFFF;//
      TIM1->PSC = 71;//CPU工作频率72M，预分频72000000/(71+1)=1M，所以定时器1工作频率为1M
      TIM1->CCR1 = 0xFFFF;
      TIM1->RCR = 0x00;
      TIM1->DIER = 0x03;//开启比较中断
      TIM1->BDTR = 0x8000;
      TIM1->CR1 = 0x81;定时器1使能
      nvic_init(2,2,TIM1_CC_IRQn,2);
}

void TIM1_CC_IRQHandler(void) //定时器1中断
{
      u16 temp;

      if (TIM1->SR & 0x0002)
      {
            TIM1->SR &= 0xFFFD;
            LED0 = !LED0;利用LED的高低电平测量验证
            temp = TIM1->CCR1;
            TIM1->CCR1 = temp + 2; //  1M/2=500KHZ，用示波器测量是畸变的信号，且信号的频率不对，为50HZ
      }
}



下面是1M的程序如下：
void timer_init(void)
{
      RCC->APB2ENR |= 1 << 11;
      TIM1->ARR = 0xFFFF;//
      TIM1->PSC = 71;//CPU工作频率72M，预分频72000000/(71+1)=1M，所以定时器1工作频率为1M
      TIM1->CCR1 = 0xFFFF;
      TIM1->RCR = 0x00;
      TIM1->DIER = 0x03;//开启比较中断
      TIM1->BDTR = 0x8000;
      TIM1->CR1 = 0x81;定时器1使能
      nvic_init(2,2,TIM1_CC_IRQn,2);
}

void TIM1_CC_IRQHandler(void) //定时器1中断
{
      u16 temp;

      if (TIM1->SR & 0x0002)
      {
            TIM1->SR &= 0xFFFD;
            LED0 = !LED0;利用LED的高低电平测量验证
            temp = TIM1->CCR1;
            TIM1->CCR1 = temp + 1; //  1M/1=1MHZ，用示波器测量是畸变的信号，且信号的频率不对，为15HZ
      }
}