一、輸入捕獲介紹

輸入捕獲模式可以用來測(cè)量脈沖寬度或者測(cè)量頻率。

除了基本定時(shí)器，通用和高級(jí)均有輸入捕獲功能。

TIMx_CCMR1(捕獲/比較模式寄存器) - 通道1和2的控制

TIMx_CCMR2(捕獲/比較模式寄存器) - 通道3和4的控制

以下將分別使用通用定時(shí)器和高級(jí)定時(shí)器實(shí)現(xiàn)超聲波測(cè)距。需要說明的是，代碼中的TIM×CH×_CAPTURE_STA我們定義其低八位含義如下：

二、通用/高級(jí)定時(shí)器實(shí)現(xiàn)超聲波測(cè)距

通用定時(shí)器輸入捕獲以TIM3的CH3為例，對(duì)應(yīng)IO為PB1。PB0實(shí)現(xiàn)觸發(fā)功能

當(dāng)然還需要配合printf一起使用，<參考這里>

完整工程可見github<傳送門>

timer.c

#include "timer.h"

#include "delay.h"

#include "usart.h"

//**************以下TIM1實(shí)現(xiàn)超聲波測(cè)距****************//

u16 TIM1CH1_CAPTURE_STA,TIM1CH1_CAPTURE_VAL;

void TIM1_Cap_Init(u16 arr,u16 psc)

{

GPIO_InitTypeDef GPIO_InitStructure;

TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;

NVIC_InitTypeDef NVIC_InitStructure;

TIM_ICInitTypeDef TIM_ICInitStructure;

RCC_APB2PeriphClockCmd(RCC_APB2Periph_TIM1, ENABLE);

RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA, ENABLE);  

RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB, ENABLE);  //使能GPIOB時(shí)鐘

GPIO_InitStructure.GPIO_Pin  = GPIO_Pin_1;     

GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;     //PB1輸出 

GPIO_InitStructure.GPIO_Speed = GPIO_Speed_2MHz;     //2M

GPIO_Init(GPIOB, &GPIO_InitStructure);

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_8;  

GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IPD; 

GPIO_Init(GPIOA, &GPIO_InitStructure);

TIM_TimeBaseStructInit(&TIM_TimeBaseStructure);//設(shè)置缺省值,這一步最好加上

TIM_TimeBaseStructure.TIM_Period = arr; //自動(dòng)重裝載寄存器周期的值，溢出值

TIM_TimeBaseStructure.TIM_Prescaler =psc; //時(shí)鐘頻率預(yù)分頻值

TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1; //設(shè)置時(shí)鐘分割:輸入捕獲模式用來濾波

TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;  //TIM向上計(jì)數(shù)模式

TIM_TimeBaseStructure.TIM_RepetitionCounter=0;//設(shè)置重復(fù)溢出次數(shù)，就是多少次溢出后進(jìn)入中斷，一般為0，只有高級(jí)定時(shí)器才有用

TIM_TimeBaseInit(TIM1, &TIM_TimeBaseStructure); 

TIM_ICStructInit(&TIM_ICInitStructure);//設(shè)置缺省值,這一步最好加上

TIM_ICInitStructure.TIM_ICPolarity = TIM_ICPolarity_Rising; //上升沿捕獲

TIM_ICInitStructure.TIM_ICSelection = TIM_ICSelection_DirectTI; //映射到TI1上

TIM_ICInitStructure.TIM_ICPrescaler = TIM_ICPSC_DIV1;   //配置輸入分頻,不分頻 

TIM_ICInitStructure.TIM_ICFilter = 0x00;   //IC1F=0000 配置輸入濾波器 0不濾波

TIM_ICInitStructure.TIM_Channel = TIM_Channel_1; //IC1映射到TI1上，這四句不能合并

TIM_ICInit(TIM1, &TIM_ICInitStructure);

//中斷分組初始化

NVIC_InitStructure.NVIC_IRQChannel = TIM1_CC_IRQn;  

NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0; 

NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0; 

NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE; 

NVIC_Init(&NVIC_InitStructure);   

TIM_ITConfig(TIM1,TIM_IT_Update|TIM_IT_CC1,ENABLE);   //允許更新中斷，允許CC1IE,CC2IE,CC3IE,CC4IE捕獲中斷

TIM_CtrlPWMOutputs(TIM1,ENABLE); //主輸出使能

TIM_Cmd(TIM1, ENABLE); //使能定時(shí)器1

}

void Read_TIM1Distane(void)

{   

PBout(1)=1;

delay_us(15);  

PBout(1)=0;

if(TIM1CH1_CAPTURE_STA&0X80)

{

Distance=TIM1CH1_CAPTURE_STA&0X3F;

Distance*=65536;         //溢出時(shí)間總和

Distance+=TIM1CH1_CAPTURE_VAL; //得到總的高電平時(shí)間

Distance = Distance*170/1000;

printf("%d rn",Distance);

TIM1CH1_CAPTURE_STA = 0;

}

}

void TIM1_CC_IRQHandler(void)

{

if((TIM1CH1_CAPTURE_STA&0X80) == 0)

{

if (TIM_GetITStatus(TIM1, TIM_IT_Update) != RESET)

{

  //通道1

if(TIM1CH1_CAPTURE_STA&0X40)//已經(jīng)捕獲到高電平了

{

if((TIM1CH1_CAPTURE_STA&0X3F)==0X3F)//高電平太長(zhǎng)了

{

TIM1CH1_CAPTURE_STA|=0X80;

TIM1CH1_CAPTURE_VAL = 0xFFFF;

}

else

{

TIM1CH1_CAPTURE_STA++;

}

}

}

//通道1

if (TIM_GetITStatus(TIM1, TIM_IT_CC1) != RESET) //捕獲1發(fā)生捕獲事件

{

if (TIM1CH1_CAPTURE_STA & 0X40) //捕獲到一個(gè)下降沿

{

TIM1CH1_CAPTURE_STA|=0X80;

TIM1CH1_CAPTURE_VAL = TIM_GetCapture1(TIM1);//記錄下此時(shí)的定時(shí)器計(jì)數(shù)值

TIM_OC1PolarityConfig(TIM1, TIM_ICPolarity_Rising); //設(shè)置為上升沿捕獲

}

else //發(fā)生捕獲時(shí)間但不是下降沿，第一次捕獲到上升沿，記錄此時(shí)的定時(shí)器計(jì)數(shù)值

{

TIM1CH1_CAPTURE_STA = 0;

TIM1CH1_CAPTURE_VAL = 0;

TIM1CH1_CAPTURE_STA |= 0X40; //標(biāo)記已捕獲到上升沿

TIM_SetCounter(TIM1, 0); //清空計(jì)數(shù)器

TIM_OC1PolarityConfig(TIM1, TIM_ICPolarity_Falling);//設(shè)置為下降沿捕獲

}

}

}

    TIM_ClearITPendingBit(TIM1, TIM_IT_CC1|TIM_IT_Update); //清除中斷標(biāo)志位

}

//**************以下TIM3實(shí)現(xiàn)超聲波測(cè)距****************//

u16 TIM3CH3_CAPTURE_STA,TIM3CH3_CAPTURE_VAL;

void TIM3_Cap_Init(u16 arr,u16 psc)

{  

GPIO_InitTypeDef GPIO_InitStructure;

TIM_TimeBaseInitTypeDef  TIM_TimeBaseStructure;

NVIC_InitTypeDef NVIC_InitStructure;

TIM_ICInitTypeDef  TIM3_ICInitStructure;

RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE); //使能TIM3時(shí)鐘

RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB, ENABLE);  //使能GPIOB時(shí)鐘

GPIO_InitStructure.GPIO_Pin  = GPIO_Pin_0; 

GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IPD; //PB0 輸入  

GPIO_Init(GPIOB, &GPIO_InitStructure);

GPIO_InitStructure.GPIO_Pin  = GPIO_Pin_1;     

GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;     //PB1輸出 

GPIO_InitStructure.GPIO_Speed = GPIO_Speed_2MHz;     //2M

GPIO_Init(GPIOB, &GPIO_InitStructure);

//初始化定時(shí)器3 TIM3  

TIM_TimeBaseStructure.TIM_Period = arr; //設(shè)定計(jì)數(shù)器自動(dòng)重裝值 

TIM_TimeBaseStructure.TIM_Prescaler =psc; //預(yù)分頻器   

TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1; //設(shè)置時(shí)鐘分割:TDTS = Tck_tim

TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;  //TIM向上計(jì)數(shù)模式

TIM_TimeBaseInit(TIM3, &TIM_TimeBaseStructure); //根據(jù)TIM_TimeBaseInitStruct中指定的參數(shù)初始化TIMx的時(shí)間基數(shù)單位

//初始化TIM3輸入捕獲參數(shù)

TIM3_ICInitStructure.TIM_Channel = TIM_Channel_3; //CC1S=03 選擇輸入端 IC3映射到TI1上

TIM3_ICInitStructure.TIM_ICPolarity = TIM_ICPolarity_Rising; //上升沿捕獲

TIM3_ICInitStructure.TIM_ICSelection = TIM_ICSelection_DirectTI;

TIM3_ICInitStructure.TIM_ICPrescaler = TIM_ICPSC_DIV1; //配置輸入分頻,不分頻 

TIM3_ICInitStructure.TIM_ICFilter = 0x00;//配置輸入濾波器 不濾波

TIM_ICInit(TIM3, &TIM3_ICInitStructure);

//中斷分組初始化

NVIC_InitStructure.NVIC_IRQChannel = TIM3_IRQn;  //TIM3中斷

NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 2;  //先占優(yōu)先級(jí)2級(jí)

NVIC_InitStructure.NVIC_IRQChannelSubPriority = 2;  //從優(yōu)先級(jí)0級(jí)

NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE; //IRQ通道被使能

NVIC_Init(&NVIC_InitStructure);  //根據(jù)NVIC_InitStruct中指定的參數(shù)初始化外設(shè)NVIC寄存器

TIM_ITConfig(TIM3,TIM_IT_Update|TIM_IT_CC3,ENABLE);//允許更新中斷 ,允許CC3IE捕獲中斷

TIM_Cmd(TIM3,ENABLE ); //使能定時(shí)器3

}

void Read_TIM3Distane(void)

{   

PBout(1)=1;

delay_us(15);  

PBout(1)=0;

if(TIM3CH3_CAPTURE_STA&0X80)//成功捕獲到了一次高電平

{

Distance=TIM3CH3_CAPTURE_STA&0X3F;

Distance*=65536;         //溢出時(shí)間總和

Distance+=TIM3CH3_CAPTURE_VAL; //得到總的高電平時(shí)間

Distance=Distance*170/1000;

printf("%d rn",Distance);

TIM3CH3_CAPTURE_STA=0; //開啟下一次捕獲

}

}

void TIM3_IRQHandler(void)

{           

if((TIM3CH3_CAPTURE_STA&0X80)==0)//還未成功捕獲

{

if (TIM_GetITStatus(TIM3, TIM_IT_Update) != RESET)//溢出

{     

if(TIM3CH3_CAPTURE_STA&0X40)//已經(jīng)捕獲到高電平了

{

if((TIM3CH3_CAPTURE_STA&0X3F)==0X3F)//高電平太長(zhǎng)了

{

TIM3CH3_CAPTURE_STA|=0X80;//標(biāo)記成功捕獲了一次

TIM3CH3_CAPTURE_VAL=0XFFFF;

}

else 

TIM3CH3_CAPTURE_STA++;

}  

}

if (TIM_GetITStatus(TIM3, TIM_IT_CC3) != RESET)//捕獲3發(fā)生捕獲事件

{

if(TIM3CH3_CAPTURE_STA&0X40) //捕獲到一個(gè)下降沿

{  

TIM3CH3_CAPTURE_STA|=0X80; //標(biāo)記成功捕獲到一次高電平脈寬

TIM3CH3_CAPTURE_VAL=TIM_GetCapture3(TIM3); //獲取當(dāng)前的捕獲值.

TIM_OC3PolarityConfig(TIM3, TIM_ICPolarity_Rising); //設(shè)置為上升沿捕獲

}

else  //還未開始,第一次捕獲上升沿

{

TIM3CH3_CAPTURE_STA=0; //清空

TIM3CH3_CAPTURE_VAL=0;

TIM3CH3_CAPTURE_STA|=0X40; //標(biāo)記捕獲到了上升沿

TIM_SetCounter(TIM3, 0); //清空計(jì)數(shù)器

TIM_OC3PolarityConfig(TIM3, TIM_ICPolarity_Falling);//設(shè)置為下降沿捕獲

}     

}              

}

TIM_ClearITPendingBit(TIM3, TIM_IT_Update|TIM_IT_CC3); //清除中斷標(biāo)志位

}

timer.h

#ifndef __TIMERs_H

#define __TIMERs_H

#include "sys.h"

#include "stm32f10x.h"

extern u32 Distance;

//******TIM1相關(guān)***********//

void TIM1_Cap_Init(u16 arr,u16 psc);

void Read_TIM1Distane(void);

//******TIM3相關(guān)***********//

void TIM3_Cap_Init(u16 arr,u16 psc);

void Read_TIM3Distane(void);

#endif

main.c

#include "led.h"

#include "delay.h"

#include "sys.h"

#include "usart.h"

#include "timer.h"

#define jishu_pinlv_psc 71

/************************************************

 printf使用串口2、波特率115200

 USART2_TX GPIOA.2，USART2_RX GPIOA.3

 超聲波測(cè)距【輸入捕獲】

 TIM1_CH1(PA8) 

 TIM3_CH3(PB0)

************************************************/

u32 Distance;

int main(void)

{

delay_init();     //延時(shí)函數(shù)初始化   

NVIC_PriorityGroupConfig(NVIC_PriorityGroup_2); //設(shè)置NVIC中斷分組2:2位搶占優(yōu)先級(jí)，2位響應(yīng)優(yōu)先級(jí)

uart_init(115200); //串口初始化為115200

LED_Init();

TIM3_Cap_Init(0xFFFF,71);

printf("okrn");

LED = 0;

while(1)

{

Read_TIM3Distane();

delay_ms(200);

}

}