void tiM3_Configuration(void)
{
TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
GPIO_InitTypeDef GPIO_InitStructure;
TIM_ICInitTypeDef TIM3_ICInitStructure;
NVIC_InitTypeDef NVIC_InitStructure;
RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOD, ENABLE);
RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE);
/*GPIOA Configuration*/
GPIO_InitStructure.GPIO_Pin=GPIO_Pin_2;
GPIO_InitStructure.GPIO_Mode=GPIO_Mode_IN_FLOATING;
GPIO_InitStructure.GPIO_Speed=GPIO_Speed_50MHz;
GPIO_Init(GPIOD, &GPIO_InitStructure);
TIM_DeInit(TIM3);
/***72M下定时值的计算（（1+预分频EXTI_Prescaler）/72*(1+定时周期EXTI_Period)）*/
TIM_TimeBaseStructure.TIM_Period=0xffff;//预分频：72M/(TIM_Period+1)=72
TIM_TimeBaseStructure.TIM_Prescaler=71; //定时时间：(1/TIM_Period)*（TIM_Prescaler+1）=0.0139Us
TIM_TimeBaseStructure.TIM_ClockDivision=TIM_CKD_DIV1; //时钟分割
TIM_TimeBaseStructure.TIM_CounterMode=TIM_CounterMode_Up; //向上计数
TIM_TimeBaseInit(TIM3, &TIM_TimeBaseStructure);//Time base configuration
TIM3_ICInitStructure.TIM_Channel = TIM_Channel_1; // 选择输入端 IC1 映射到 TI1 上
TIM3_ICInitStructure.TIM_ICPolarity = TIM_ICPolarity_Rising;// 捕获下降沿
TIM3_ICInitStructure.TIM_ICSelection = TIM_ICSelection_DirectTI; //映射到TI1上
TIM3_ICInitStructure.TIM_ICPrescaler = TIM_ICPSC_DIV1; //捕获在捕获输入上每探测到一个边沿执行一次
TIM3_ICInitStructure.TIM_ICFilter = 0x00; //输入比较滤波器
TIM_ICInit(TIM3, &TIM3_ICInitStructure);
NVIC_InitStructure.NVIC_IRQChannel = TIM3_IRQn; //TIM3 中断
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 2; //先占优先级 2 级
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0; //从优先级 0 级
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE; //IRQ 通道被使能
NVIC_Init(&NVIC_InitStructure); //⑤根据指定的参数初始化 NV
// TIM_ETRClockMode2Config(TIM3, TIM_ExtTRGPSC_DIV8, TIM_ExtTRGPolarity_Inverted, 4);//8分频
TIM_ITRxExternalClockConfig(TIM3,TIM_TS_ETRF); //配置外部触发，否则不会计数
//TIM3->SMCR=0X43;
TIM_ITConfig( TIM3,TIM_IT_Update|TIM_IT_CC1,ENABLE);//允许更新中断和捕获中断
TIM_Cmd(TIM3,ENABLE ); //⑥使能定时器 3
}
void TIM3_IRQHandler(void)
{
//Fre_flag=1;
if((TIM3CH1_CAPTURE_STA&0X80)==0)//还未成功捕获
{
// Fre_flag=2;
if (TIM_GetITStatus(TIM3, TIM_IT_Update) != RESET)
{
// Fre_flag=5;
if(TIM3CH1_CAPTURE_STA&0X40)//已经捕获到高电平了
{
// Fre_flag=6;
if((TIM3CH1_CAPTURE_STA&0X3F)==0X3F)//高电平太长了
{
// Fre_flag=7;
TIM3CH1_CAPTURE_STA|=0X80;//标记成功捕获了一次
TIM3CH1_CAPTURE_VAL=0XFFFF;
}else TIM3CH1_CAPTURE_STA++;
}
}
if (TIM_GetITStatus(TIM3, TIM_IT_CC1) != RESET)//捕获 1 发生捕获事件
{
// Fre_flag=3;
if(TIM3CH1_CAPTURE_STA&0X40) //捕获到一个下降沿
{
// Fre_flag=8;
TIM3CH1_CAPTURE_STA|=0X80; //标记成功捕获到一次上升沿
TIM3CH1_CAPTURE_VAL=TIM_GetCapture1(TIM3);
TIM_OC1PolarityConfig(TIM3,TIM_ICPolarity_Rising); //设置为上升沿捕获
}
else //还未开始,第一次捕获上升沿
{
// Fre_flag=4;
TIM3CH1_CAPTURE_STA=0; //清空
TIM3CH1_CAPTURE_VAL=0;
TIM_SetCounter(TIM3,0);
TIM3CH1_CAPTURE_STA|=0X40; //标记捕获到了上升沿
TIM_OC1PolarityConfig(TIM3,TIM_ICPolarity_Falling); //设置为下降沿捕获
}
}
}
TIM_ClearITPendingBit(TIM3, TIM_IT_CC1|TIM_IT_Update); //清除中断标志位
} |
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