【STM32模块化程序】定时器输入捕获实现超声波测距

一、输入捕获介绍

输入捕获模式可以用来测量脉冲宽度或者测量频率。

除了基本定时器，通用和高级均有输入捕获功能。

TIMx_CCMR1(捕获/比较模式寄存器) - 通道1和2的控制

TIMx_CCMR2(捕获/比较模式寄存器) - 通道3和4的控制

以下将分别使用通用定时器和高级定时器实现超声波测距。需要说明的是，代码中的TIM×CH×_CAPTURE_STA我们定义其低八位含义如下：

二、通用/高级定时器实现超声波测距

通用定时器输入捕获以TIM3的CH3为例，对应IO为PB1。PB0实现触发功能

当然还需要配合printf一起使用，<参考这里>

完整工程可见github<传送门>

timer.c

#include "timer.h"

#include "delay.h"

#include "usart.h"

//**************以下TIM1实现超声波测距****************//

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时钟

GPIO_InitStructure.GPIO_Pin  = GPIO_Pin_1;     

GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;     //PB1输出 

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);//设置缺省值,这一步最好加上

TIM_TimeBaseStructure.TIM_Period = arr; //自动重装载寄存器周期的值，溢出值

TIM_TimeBaseStructure.TIM_Prescaler =psc; //时钟频率预分频值

TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1; //设置时钟分割:输入捕获模式用来滤波

TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;  //TIM向上计数模式

TIM_TimeBaseStructure.TIM_RepetitionCounter=0;//设置重复溢出次数，就是多少次溢出后进入中断，一般为0，只有高级定时器才有用

TIM_TimeBaseInit(TIM1, &TIM_TimeBaseStructure); 

TIM_ICStructInit(&TIM_ICInitStructure);//设置缺省值,这一步最好加上

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

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

TIM_ICInitStructure.TIM_ICPrescaler = TIM_ICPSC_DIV1;   //配置输入分频,不分频 

TIM_ICInitStructure.TIM_ICFilter = 0x00;   //IC1F=0000 配置输入滤波器 0不滤波

TIM_ICInitStructure.TIM_Channel = TIM_Channel_1; //IC1映射到TI1上，这四句不能合并

TIM_ICInit(TIM1, &TIM_ICInitStructure);

//中断分组初始化

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);   //允许更新中断，允许CC1IE,CC2IE,CC3IE,CC4IE捕获中断

TIM_CtrlPWMOutputs(TIM1,ENABLE); //主输出使能

TIM_Cmd(TIM1, ENABLE); //使能定时器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;         //溢出时间总和

Distance+=TIM1CH1_CAPTURE_VAL; //得到总的高电平时间

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)//已经捕获到高电平了

{

if((TIM1CH1_CAPTURE_STA&0X3F)==0X3F)//高电平太长了

{

TIM1CH1_CAPTURE_STA|=0X80;

TIM1CH1_CAPTURE_VAL = 0xFFFF;

}

else

{

TIM1CH1_CAPTURE_STA++;

}

}

}

//通道1

if (TIM_GetITStatus(TIM1, TIM_IT_CC1) != RESET) //捕获1发生捕获事件

{

if (TIM1CH1_CAPTURE_STA & 0X40) //捕获到一个下降沿

{

TIM1CH1_CAPTURE_STA|=0X80;

TIM1CH1_CAPTURE_VAL = TIM_GetCapture1(TIM1);//记录下此时的定时器计数值

TIM_OC1PolarityConfig(TIM1, TIM_ICPolarity_Rising); //设置为上升沿捕获

}

else //发生捕获时间但不是下降沿，第一次捕获到上升沿，记录此时的定时器计数值

{

TIM1CH1_CAPTURE_STA = 0;

TIM1CH1_CAPTURE_VAL = 0;

TIM1CH1_CAPTURE_STA |= 0X40; //标记已捕获到上升沿

TIM_SetCounter(TIM1, 0); //清空计数器

TIM_OC1PolarityConfig(TIM1, TIM_ICPolarity_Falling);//设置为下降沿捕获

}

}

}

    TIM_ClearITPendingBit(TIM1, TIM_IT_CC1|TIM_IT_Update); //清除中断标志位

}

//**************以下TIM3实现超声波测距****************//

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时钟

RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB, ENABLE);  //使能GPIOB时钟

GPIO_InitStructure.GPIO_Pin  = GPIO_Pin_0; 

GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IPD; //PB0 输入  

GPIO_Init(GPIOB, &GPIO_InitStructure);

GPIO_InitStructure.GPIO_Pin  = GPIO_Pin_1;     

GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;     //PB1输出 

GPIO_InitStructure.GPIO_Speed = GPIO_Speed_2MHz;     //2M

GPIO_Init(GPIOB, &GPIO_InitStructure);

//初始化定时器3 TIM3  

TIM_TimeBaseStructure.TIM_Period = arr; //设定计数器自动重装值 

TIM_TimeBaseStructure.TIM_Prescaler =psc; //预分频器   

TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1; //设置时钟分割:TDTS = Tck_tim

TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;  //TIM向上计数模式

TIM_TimeBaseInit(TIM3, &TIM_TimeBaseStructure); //根据TIM_TimeBaseInitStruct中指定的参数初始化TIMx的时间基数单位

//初始化TIM3输入捕获参数

TIM3_ICInitStructure.TIM_Channel = TIM_Channel_3; //CC1S=03 选择输入端 IC3映射到TI1上

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

TIM3_ICInitStructure.TIM_ICSelection = TIM_ICSelection_DirectTI;

TIM3_ICInitStructure.TIM_ICPrescaler = TIM_ICPSC_DIV1; //配置输入分频,不分频 

TIM3_ICInitStructure.TIM_ICFilter = 0x00;//配置输入滤波器 不滤波

TIM_ICInit(TIM3, &TIM3_ICInitStructure);

//中断分组初始化

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 = 2;  //从优先级0级

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

NVIC_Init(&NVIC_InitStructure);  //根据NVIC_InitStruct中指定的参数初始化外设NVIC寄存器

TIM_ITConfig(TIM3,TIM_IT_Update|TIM_IT_CC3,ENABLE);//允许更新中断 ,允许CC3IE捕获中断

TIM_Cmd(TIM3,ENABLE ); //使能定时器3

}

void Read_TIM3Distane(void)

{   

PBout(1)=1;

delay_us(15);  

PBout(1)=0;

if(TIM3CH3_CAPTURE_STA&0X80)//成功捕获到了一次高电平

{

Distance=TIM3CH3_CAPTURE_STA&0X3F;

Distance*=65536;         //溢出时间总和

Distance+=TIM3CH3_CAPTURE_VAL; //得到总的高电平时间

Distance=Distance*170/1000;

printf("%d rn",Distance);

TIM3CH3_CAPTURE_STA=0; //开启下一次捕获

}

}

void TIM3_IRQHandler(void)

{           

if((TIM3CH3_CAPTURE_STA&0X80)==0)//还未成功捕获

{

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

{     

if(TIM3CH3_CAPTURE_STA&0X40)//已经捕获到高电平了

{

if((TIM3CH3_CAPTURE_STA&0X3F)==0X3F)//高电平太长了

{

TIM3CH3_CAPTURE_STA|=0X80;//标记成功捕获了一次

TIM3CH3_CAPTURE_VAL=0XFFFF;

}

else 

TIM3CH3_CAPTURE_STA++;

}  

}

if (TIM_GetITStatus(TIM3, TIM_IT_CC3) != RESET)//捕获3发生捕获事件

{

if(TIM3CH3_CAPTURE_STA&0X40) //捕获到一个下降沿

{  

TIM3CH3_CAPTURE_STA|=0X80; //标记成功捕获到一次高电平脉宽

TIM3CH3_CAPTURE_VAL=TIM_GetCapture3(TIM3); //获取当前的捕获值.

TIM_OC3PolarityConfig(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

{

TIM3CH3_CAPTURE_STA=0; //清空

TIM3CH3_CAPTURE_VAL=0;

TIM3CH3_CAPTURE_STA|=0X40; //标记捕获到了上升沿

TIM_SetCounter(TIM3, 0); //清空计数器

TIM_OC3PolarityConfig(TIM3, TIM_ICPolarity_Falling);//设置为下降沿捕获

}     

}              

}

TIM_ClearITPendingBit(TIM3, TIM_IT_Update|TIM_IT_CC3); //清除中断标志位

}

timer.h

#ifndef __TIMERs_H

#define __TIMERs_H

#include "sys.h"

#include "stm32f10x.h"

extern u32 Distance;

//******TIM1相关***********//

void TIM1_Cap_Init(u16 arr,u16 psc);

void Read_TIM1Distane(void);

//******TIM3相关***********//

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

 超声波测距【输入捕获】

 TIM1_CH1(PA8) 

 TIM3_CH3(PB0)

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

u32 Distance;

int main(void)

{

delay_init();     //延时函数初始化   

NVIC_PriorityGroupConfig(NVIC_PriorityGroup_2); //设置NVIC中断分组2:2位抢占优先级，2位响应优先级

uart_init(115200); //串口初始化为115200

LED_Init();

TIM3_Cap_Init(0xFFFF,71);

printf("okrn");

LED = 0;

while(1)

{

Read_TIM3Distane();

delay_ms(200);

}

}