用定时器输入捕获
[mw_shl_code=c,true]void Timerx_Init(u16 arr,u16 psc) //
{ //
RCC->APB1ENR|=1<<0; // ?????¨?±?÷2?±??
RCC->APB2ENR|=1<<2; //????IO??A?±??
GPIOA->CRL&=0XFFFFFF0F; //?è??PA1??????????
GPIOA->CRL|=0X00000080;
GPIOA->ODR|=0<<1; //????
TIM2->ARR=arr; // ?è?¨?????÷×?????×°?????¨1ms?©
TIM2->  SC=psc; // ?¤·????÷7200??????10KH???±??
TIM2->CCMR1|=1<<8; // CC2?¨??±?????????????IC2??????TI2??
TIM2->CCMR1|=0<<12; // ????????2???¨?÷
TIM2->CCMR1|=0<<10; // ????/????2?¤·????÷
TIM2->CCER&=~(1<<5); // ????/????2????????
TIM2->CCER|=1<<4; // ????/????2????????
TIM2->DIER|=1<<2; // ???í??·?????
TIM2->CR1|=0X01; // ?????¨?±?÷2
TIM2->CCR1=500; //?¤×°??
TIM2->CCR2=500;
MY_NVIC_Init(0,0,TIM2_IRQChannel,2);// ????0??×???????0??×é2
}[/mw_shl_code]
[mw_shl_code=c,true]void TIM2_IRQHandler(void) // ????2????
{ //
u16 tsr;
tsr=TIM2->SR;
if((TIM2CH2_CAPTURE_STA&0X80)==0)
{
if(tsr&0x04)
{
if(TIM2CH2_CAPTURE_STA&0X40)
{
if(TIM2CH2_CAPTURE_STA&0X20)
{
TIM2CH2_CAPTURE_VAL2=TIM2->CCR2;
TIM2CH2_CAPTURE_STA|=0X80;
TIM2->CNT=0;
TIM2->CCER&=~(1<<5);
TIM2->SR&=~(1<<2);
TIM2->CCER&=~(1<<4);
}
else
{
TIM2CH2_CAPTURE_VAL1=TIM2->CCR2;
TIM2CH2_CAPTURE_STA|=0X20;
TIM2->CCER&=~(1<<5) ;
TIM2->CNT=0;
TIM2->SR&=~(1<<2);
//TIM2->CCER&=~(1<<4);
}
}else
{
TIM2->CNT=0;
TIM2CH2_CAPTURE_STA=0;
TIM2CH2_CAPTURE_VAL1=0;
TIM2CH2_CAPTURE_VAL2=0;
TIM2CH2_CAPTURE_STA|=0X40;
TIM2->CCER|=1<<5;
}
TIM2->SR&=~(1<<2);
}
}
}[/mw_shl_code]
[mw_shl_code=c,true] if(TIM2CH2_CAPTURE_STA&0X80)
{
temp2=TIM2CH2_CAPTURE_VAL1*100/(TIM2CH2_CAPTURE_VAL2+TIM2CH2_CAPTURE_VAL1);
temperature=(temp2-32)*100/47;
// if( temperature>50)time++;
// USART1->DR=temperature;
// while ((USART1->SR&0X40)==0);//????·????ê??
TIM2CH2_CAPTURE_STA=0;
TIM2->CCER|=1<<4; // ????/????2????????
} [/mw_shl_code]
以上程序完成了对一个周期的波形进行高低电平持续时间的测量，以此计算外部PWM信号的占空比，实际应用是对PWM输出型温度传感器SMT160-30输出的温度信号解析。对一帧数据的测量可以采用类似的办法，正负边沿交替触发，用寄存器组存储每次边缘变化时的定时器捕获值并清零计数器。 | 
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发表于 2015-7-16 15:38:49
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