from machine import Pin, PWM
import time

class UltrasonicSensor:
    def __init__(self, trigger_pin, echo_pin):
        self.trigger = Pin(trigger_pin, Pin.OUT)
        self.echo = Pin(echo_pin, Pin.IN)

    def distance(self):
        self.trigger.value(1)
        time.sleep_us(10)
        self.trigger.value(0)
        
        timeout = time.ticks_us() + 1000000  # Timeout set to 1 second
        while self.echo.value() == 0 and time.ticks_us() < timeout:
            pulse_start = time.ticks_us()
        timeout = time.ticks_us() + 1000000  # Reset timeout
        while self.echo.value() == 1 and time.ticks_us() < timeout:
            pulse_end = time.ticks_us()
        
        pulse_duration = pulse_end - pulse_start
        distance_cm = (pulse_duration * 0.0343) / 2
        return distance_cm

led1 = Pin(12, Pin.OUT)
led2 = Pin(13, Pin.OUT)
led3 = Pin(14, Pin.OUT)

buzzer = PWM(Pin(23))
buzzer.freq(1047)

led_pins = [led1, led2, led3]

def activate_buzzer():
    buzzer.duty(512)
    time.sleep(2)
    buzzer.duty(0)

sensor = UltrasonicSensor(trigger_pin=12, echo_pin=13)

try:
    while True:
        distance = sensor.distance()
        print('distance =', distance)

        if distance < 4.5:
            led1.value(1)
            led2.value(0)
            led3.value(0)

        elif 4.5 <= distance < 9:
            led1.value(1)
            led2.value(1)
            led3.value(0)

        else:
            led1.value(1)
            led2.value(1)
            led3.value(1)
            activate_buzzer()

except KeyboardInterrupt:
    buzzer.deinit()
    for led_pin in led_pins:
        led_pin.off()