#RasPi script to link a passive buzzer to a distance sensor. The effect is similar to a geiger counter. Based on this code to play melodies on a passive buzzer: http://www.linuxcircle.com/2015/04/12/how-to-play-piezo-buzzer-tunes-on-raspberry-pi-gpio-with-pwm/

geyger.py

import RPi.GPIO as GPIO   #import the GPIO library
import time               #import the time library
from gpiozero import DistanceSensor

class Buzzer(object):
 def __init__(self):
  GPIO.setmode(GPIO.BCM)  
  self.buzzer_pin = 22 #set to GPIO pin 22
  GPIO.setup(self.buzzer_pin, GPIO.IN)
  GPIO.setup(self.buzzer_pin, GPIO.OUT)
  print("buzzer ready")

 def __del__(self):
  class_name = self.__class__.__name__
  print (class_name, "finished")

 def buzz(self,pitch, duration):   #create the function “buzz” and feed it the pitch and duration)
 
  if(pitch==0):
   time.sleep(duration)
   return
  period = 1.0 / pitch     #in physics, the period (sec/cyc) is the inverse of the frequency (cyc/sec)
  delay = period / 2     #calcuate the time for half of the wave  
  cycles = int(duration * pitch)   #the number of waves to produce is the duration times the frequency

  for i in range(cycles):    #start a loop from 0 to the variable “cycles” calculated above
   GPIO.output(self.buzzer_pin, True)   #set pin 22 to high
   time.sleep(delay)    #wait with pin 18 high
   GPIO.output(self.buzzer_pin, False)    #set pin 22 to low
   time.sleep(delay)    #wait with pin 18 low


 def play(self, dist):
  GPIO.setmode(GPIO.BCM)
  GPIO.setup(self.buzzer_pin, GPIO.OUT)
  self.buzz((dist+120), 0.04)
  time.sleep(0.01)
  
if __name__ == "__main__":
  buzzer = Buzzer()
  sensor = DistanceSensor(18, 17)
  while True:
      print('Distance to nearest object is', sensor.distance, 'm')
      buzzer.play((sensor.distance)*200)