from machine import Pin,PWM
import utime

trigger = Pin(2, Pin.OUT)
echo = Pin(4, Pin.IN)
pin_buzzer = 21


WATER_LEVEL_LOW = 100
WATER_LEVEL_HIGH = 400

def ultra():
    trigger.low()
    utime.sleep_us(2)
    trigger.high()
    utime.sleep_us(5)
    trigger.low()

    while echo.value() == 0:
        signaloff = utime.ticks_us()
    while echo.value() ==1:
        signalon = utime.ticks_us()
    timespeed = signalon-signaloff
    distance = (timespeed*0.0343)/2
    return distance

def activate_buzzer():
    buzzer = PWM(Pin(pin_buzzer))

    buzzer.freq(500)
    buzzer.duty_u16(45618)
    utime.sleep(1)
  
def deactivate_buzzer():
    buzzer = PWM(Pin(pin_buzzer))
    buzzer.duty_u16(0)
    # Or you can deinitialize it if necessary
    # buzzer.deinit()
    print("Buzzer deactivated")

def distance():
    distance = ultra()
    print("The distance measured is:",distance,"cm")

    if distance<WATER_LEVEL_LOW:
        print("Water level is too low")
        activate_buzzer()
    elif distance>WATER_LEVEL_HIGH:
        print("Water level is too high")
        activate_buzzer()
    else:
        print("\nThe water level is normal.")
        deactivate_buzzer()
        

while True:
    distance()
    utime.sleep(1)