利用STM32输入捕获写的一个超声波测距的源程序串口显示 -

void TIM3_CAP_Init(u16 arr,u16 psc)
{
GPIO_InitTypeDef GPIO_InitStructure;
TIM_TimeBaseInitTypeDef TIM_TimeBaseInitStructure;
TIM_ICInitTypeDef TIM_ICInitStructure;
NVIC_InitTypeDef NVIC_InitStructure;
//使能相应时钟
RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3,ENABLE);
RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA,ENABLE);
//GPIOA 0 初始化
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IPD; //输入下拉
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_6;
GPIO_Init(GPIOA,&GPIO_InitStructure);
GPIO_ResetBits(GPIOA,GPIO_Pin_0); //设置为低电平
//初始化定时器
TIM_TimeBaseInitStructure.TIM_ClockDivision = TIM_CKD_DIV1; //不分频
TIM_TimeBaseInitStructure.TIM_CounterMode = TIM_CounterMode_Up; //向上计数
TIM_TimeBaseInitStructure.TIM_Period = arr; //自动重装载的值
TIM_TimeBaseInitStructure.TIM_Prescaler = psc; //预分频的系数
TIM_TimeBaseInit(TIM3,&TIM_TimeBaseInitStructure);
//初始化捕获通道
TIM_ICInitStructure.TIM_Channel = TIM_Channel_1; //通道1
TIM_ICInitStructure.TIM_ICFilter = 0x00; //不使用虑波器
TIM_ICInitStructure.TIM_ICPolarity = TIM_ICPolarity_Rising; //设置为上升沿捕获
TIM_ICInitStructure.TIM_ICPrescaler = TIM_ICPSC_DIV1; //分频不分频
TIM_ICInitStructure.TIM_ICSelection = TIM_ICSelection_DirectTI; //通道的映射关系
TIM_ICInit(TIM3,&TIM_ICInitStructure);
//初始化中断
NVIC_InitStructure.NVIC_IRQChannel = TIM3_IRQn; //TIM3中断
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 2;
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;
NVIC_Init(&NVIC_InitStructure);
//开启捕获和更新中断
TIM_ITConfig(TIM3,TIM_IT_Update | TIM_IT_CC1, ENABLE);
//使能定时器
TIM_Cmd(TIM3,ENABLE);
}
u8 TIM3CH1_CAPTURE_STA = 0;
u16 TIM3CH1_CAPTURE_VAL = 0;
//中断服务函数
void TIM3_IRQHandler(void)
{
if((TIM3CH1_CAPTURE_STA & 0x80) == 0) //如果还没完成捕获
{
if(TIM_GetITStatus(TIM3,TIM_IT_Update) != RESET) //更新中断来了
{
if(TIM3CH1_CAPTURE_STA & 0x40) //如果上一次捕获到高电平
{
if((TIM3CH1_CAPTURE_STA & 0x3f) == 0x3f) //如果定时器溢出次数记满了
{
TIM3CH1_CAPTURE_STA |= 0x80; //记满了强制捕获完成
TIM3CH1_CAPTURE_VAL = 0xffff; //记满
}
else //否则
{
TIM3CH1_CAPTURE_STA ++; //每来一次更新中断自加一次
}
}
}
if(TIM_GetITStatus(TIM3,TIM_IT_CC1) != RESET) //如果捕获中断来了
{
if(TIM3CH1_CAPTURE_STA & 0x40) //如果上次捕获到高电平
{
TIM3CH1_CAPTURE_STA |= 0x80; //捕获完成
TIM3CH1_CAPTURE_VAL = TIM_GetCapture1(TIM3); //将通道的值给 VAL
TIM_OC1PolarityConfig(TIM3,TIM_ICPolarity_Rising); //完成捕获还要设置下降沿触发
}
else //第一次捕获
{
TIM3CH1_CAPTURE_STA = 0; //清零
TIM3CH1_CAPTURE_VAL = 0;
TIM_SetCounter(TIM3,0);
TIM3CH1_CAPTURE_STA |= 0x40; //采集到高电平了
TIM_OC1PolarityConfig(TIM3,TIM_ICPolarity_Falling); //设置下降沿触发
}
}
}
TIM_ClearITPendingBit(TIM3,TIM_IT_Update | TIM_IT_CC1); //清除中断标志位
}

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