### 超声波测距原理 超声波测距基于时间飞行法(Time of Flight, TOF)，即通过测量声音脉冲从发射到接收之间的时间差来计算距离。当超声波模块发出高频声波并遇到物体反射回来时，传感器会检测回波所需的时间，并据此推算目标的距离[^1]。 ### 接线说明与硬件连接 对于HC-SR04这类常见的超声波传感器而言，其引脚定义如下： - VCC 连接到电源正极 (通常为5V) - GND 连接到电源负极 - Trig 触发信号输入端子 - Echo 反馈信号输出端子 这些接口应当按照具体开发板的要求正确接入电路中。 ### Python编程实现示例 下面是一个简单的Python程序用于控制树莓派上的HC-SR04超声波传感器完成基本的测距功能： ```python import RPi.GPIO as GPIO # Import GPIO library import time # Import time library GPIO.setmode(GPIO.BCM) # Set pin numbering to board numbering TRIG = 23 # Associate pin 23 to TRIG ECHO = 24 # Associate pin 24 to ECHO print("Distance measurement in progress") GPIO.setup(TRIG, GPIO.OUT) # Set pin as GPIO out GPIO.setup(ECHO, GPIO.IN) # Set pin as GPIO in while True: GPIO.output(TRIG, False) # Set TRIG as LOW print("Waiting For Sensor To Settle") time.sleep(2) # Delay of 2 seconds GPIO.output(TRIG, True) # Set TRIG as HIGH time.sleep(0.00001) # Delay of 0.00001 seconds GPIO.output(TRIG, False) # Set TRIG as LOW while GPIO.input(ECHO)==0: # Check whether the ECHO is LOW pulse_start = time.time() # Saves the last known time of LOW pulse while GPIO.input(ECHO)==1: # Check whether the ECHO is HIGH pulse_end = time.time() # Saves the last known time of HIGH pulse pulse_duration = pulse_end - pulse_start # Get pulse duration to a variable distance = pulse_duration * 17150 # Multiply pulse duration by 17150 to get distance distance = round(distance, 2) # Round to two decimal points if distance > 2 and distance < 400: # Check whether the distance is within range print(f"Distance:{distance} cm") # Print distance with 0.5 cm calibration else: print("Out Of Range") # display out of range ``` 此段代码实现了对超声波传感器的基本操作逻辑，包括触发信号发送、等待响应以及根据返回数据计算实际距离等功能。