print("This program will integrate ESP32 with ultrasonic sensor")

# Import necessary modules/libraries
import hcsr04  # ultrasonic lib
from utime import sleep
from machine import Pin, PWM  # PWM = Pulse Width Modulation

# Create an object called ultrasonic_sensor
ultrasonic_sensor = hcsr04.HCSR04(trigger_pin=13, echo_pin=27, echo_timeout_us=500*2*30)

# Declare buzzer connection
buzzer = PWM(Pin(23), Pin.OUT)

while True:
    # Test the ultrasonic sensor
        distance_cm = ultrasonic_sensor.distance_cm()  # use for decimal point number
            distance_mm = ultrasonic_sensor.distance_mm()  # use for whole number

                # Display the distance values on Serial Monitor
                    print('An object is detected in:', distance_cm, 'cm')
                        print('An object is detected in:', distance_mm, 'mm')
                            print('------------------------------------------------')
                                print('\n')

                                    if distance_cm < 50:
                                            for i in range(10):
                                                        buzzer.init(freq=1703, duty=400)
                                                                    sleep(0.5)
                                                                                buzzer.init(freq=1, duty=0)
                                                                                            sleep(0.5)
                                                                                                elif 50 <= distance_cm < 150:
                                                                                                        for i in range(10):
                                                                                                                    buzzer.init(freq=1703, duty=400)
                                                                                                                                sleep(1)
                                                                                                                                            buzzer.init(freq=1, duty=0)
                                                                                                                                                        sleep(1)
                                                                                                                                                            else:
                                                                                                                                                                    buzzer.init(freq=1, duty=0)

                                                                                                                                                                        sleep(5)