STM32超声波测距程序

超声波测距模块：HCSR-04
采用定时器及外部中断方式

/*******************************************************************************    超声波测距   测试平台：STM32F103ZET6最小系统  引脚连接：TRIG--PC0   ECHO--PC1*******************************************************************************/#include "sonar_hcsr04.h"#include "systime.h"#define SONAR_PORT  GPIOC#define TRIG_PIN    GPIO_Pin_0#define ECHO_PIN    GPIO_Pin_1static volatile uint32_t measurement;void hcsr04Init(void){    GPIO_InitTypeDef GPIO_InitStructure;        EXTI_InitTypeDef EXTI_InitStructure;    TIM_TimeBaseInitTypeDef  TIM_TimeBaseInitStructure;    RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOC , ENABLE);    GPIO_InitStructure.GPIO_Pin = TRIG_PIN;    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;    GPIO_Init(SONAR_PORT, &GPIO_InitStructure);    GPIO_InitStructure.GPIO_Pin = ECHO_PIN;                       GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;             GPIO_Init(SONAR_PORT, &GPIO_InitStructure);     GPIO_ResetBits(SONAR_PORT, ECHO_PIN);    GPIO_EXTILineConfig(GPIO_PortSourceGPIOC, GPIO_PinSource1);  // 中断线以及中断初始化配置    EXTI_ClearITPendingBit(EXTI_Line1);    EXTI_InitStructure.EXTI_Line = EXTI_Line1;    EXTI_InitStructure.EXTI_Mode = EXTI_Mode_Interrupt;     EXTI_InitStructure.EXTI_Trigger = EXTI_Trigger_Rising_Falling;    EXTI_InitStructure.EXTI_LineCmd = ENABLE;    EXTI_Init(&EXTI_InitStructure);         /* Enable TIM5 clock */    RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM5, ENABLE);    /* TIME5 base configuration */    TIM_TimeBaseInitStructure.TIM_Period = 0xFFFF;                   //      TIM_TimeBaseInitStructure.TIM_Prescaler = 72-1;                  // 设置预分频,F=72MHz/72=1MHz   T=1us    TIM_TimeBaseInitStructure.TIM_ClockDivision = 0;                 // 设置时钟分频系数,不分频    TIM_TimeBaseInitStructure.TIM_CounterMode = TIM_CounterMode_Up;  // 向上计数模式    TIM_TimeBaseInit(TIM5, &TIM_TimeBaseInitStructure);              // 初始化TIME5    TIM_Cmd(TIM5, DISABLE); }/** * 发出测试信号 */void hcsr04StartRanging(void){    GPIO_SetBits(SONAR_PORT, TRIG_PIN);    delay_us(20);   //  The width of trig signal must be greater than 10us    GPIO_ResetBits(SONAR_PORT, TRIG_PIN);}/** * 根据公式计算距离  * @return distance units:cm  */float hcsr04GetDistance(void){    // distance = measurement/2/1000*340 = measurement/59 (cm)  measurement-units:us    float distance = measurement / 58.8;   // measurement-units:us    return distance;}static void ECHO_EXTI_IRQHandler(void){    if (EXTI_GetITStatus(EXTI_Line1) != RESET) {        if (GPIO_ReadInputDataBit(SONAR_PORT, ECHO_PIN) != 0) {  // 等待高电平回波            TIM_Cmd(TIM5, ENABLE);          } else {            TIM_Cmd(TIM5, DISABLE);              measurement = TIM_GetCounter(TIM5);            TIM_SetCounter(TIM5, 0);         }    }    EXTI_ClearITPendingBit(EXTI_Line1);}void EXTI1_IRQHandler(void){    ECHO_EXTI_IRQHandler();}