STM32超声波测距程序

ID:338925 · 发表于 2018-6-5 21:26

#include "timer.h"
#include "usart.h"
#include "sys.h"
void TIM4_Cap_Init(u16 arr,u16 psc)
{
GPIO_InitTypeDef GPIO_InitStructure;
TIM_ICInitTypeDef TIM4_ICInitStructure;
TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
NVIC_InitTypeDef NVIC_InitStructure;
RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM4, ENABLE); //使能TIM4时钟
RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB, ENABLE); //使能GPIOB时钟
/*TRIG触发信号*/
GPIO_InitStructure.GPIO_Speed=GPIO_Speed_50MHz;
GPIO_InitStructure.GPIO_Mode=GPIO_Mode_Out_PP; //推挽输出
GPIO_InitStructure.GPIO_Pin=GPIO_Pin_8;
GPIO_Init(GPIOB, &GPIO_InitStructure);
GPIO_ResetBits(GPIOB,GPIO_Pin_8);
/*ECOH回响信号*/
GPIO_InitStructure.GPIO_Mode=GPIO_Mode_IN_FLOATING; //浮空输入
GPIO_InitStructure.GPIO_Pin=GPIO_Pin_9;
GPIO_Init(GPIOB, & GPIO_InitStructure);
GPIO_ResetBits(GPIOB,GPIO_Pin_9);
//初始化定时器4 TIM4
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; //不分频
TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up; //TIM向上计数模式
TIM_TimeBaseInit(TIM4, &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TIM4输入捕获参数
TIM4_ICInitStructure.TIM_Channel = TIM_Channel_4; //CC4S=01 选择输入端 IC4映射到TI4上
TIM4_ICInitStructure.TIM_ICPolarity = TIM_ICPolarity_Rising; //上升沿捕获
TIM4_ICInitStructure.TIM_ICSelection = TIM_ICSelection_DirectTI; //映射到TI4上
TIM4_ICInitStructure.TIM_ICPrescaler = TIM_ICPSC_DIV1; //配置输入分频,不分频
TIM4_ICInitStructure.TIM_ICFilter = 0x03;//IC4F=0000 配置输入滤波器不滤波
TIM_ICInit(TIM4, &TIM4_ICInitStructure);
//中断分组初始化
NVIC_InitStructure.NVIC_IRQChannel = TIM4_IRQn; //TIM4中断
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0; //先占优先级0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); //根据NVIC_InitStruct中指定的参数初始化外设NVIC寄存器
TIM_ITConfig(TIM4,TIM_IT_Update|TIM_IT_CC4,ENABLE);//允许更新中断 ,允许CC4IE捕获中断
TIM_Cmd(TIM4,ENABLE);
}
u8 TIM4CH4_CAPTURE_STA=0; //输入捕获状态
u16 TIM4CH4_CAPTURE_VAL; //输入捕获值-----用来记录捕获到下降沿的时候 TIM4 _CNT的值
//定时器4中断服务程序
void TIM4_IRQHandler(void)
{
if((TIM4CH4_CAPTURE_STA&0X80)==0)//还未成功捕获
{
if (TIM_GetITStatus(TIM4, TIM_IT_Update) != RESET)
{
if(TIM4CH4_CAPTURE_STA&0X40)//已经捕获到高电平了
{
if((TIM4CH4_CAPTURE_STA&0X3F)==0X3F)//高电平太长了
{
TIM4CH4_CAPTURE_STA|=0X80;//标记成功捕获了一次
TIM4CH4_CAPTURE_VAL=0XFFFF;
}else TIM4CH4_CAPTURE_STA++;
}
}
if (TIM_GetITStatus(TIM4, TIM_IT_CC4) != RESET)//捕获4发生捕获事件
{
if(TIM4CH4_CAPTURE_STA&0X40) //捕获到一个下降沿
{
TIM4CH4_CAPTURE_STA|=0X80; //标记成功捕获到一次上升沿
TIM4CH4_CAPTURE_VAL=TIM_GetCapture4(TIM4);
TIM_OC4PolarityConfig(TIM4,TIM_ICPolarity_Rising); //CC4P=0 设置为上升沿捕获
}else //还未开始,第一次捕获上升沿
{
TIM4CH4_CAPTURE_STA=0; //清空
TIM4CH4_CAPTURE_VAL=0;
TIM_SetCounter(TIM4,0);
TIM4CH4_CAPTURE_STA|=0X40; //标记捕获到了上升沿
TIM_OC4PolarityConfig(TIM4,TIM_ICPolarity_Falling); //CC4P=1 设置为下降沿捕获
}
}
}
TIM_ClearITPendingBit(TIM4, TIM_IT_CC4|TIM_IT_Update); //清除中断标志位
}

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