from ultrasonic import Ultrasonic
from machine import Pin, PWM
import time

ultrasonic_sensor = Ultrasonic(trigger_pin=12, echo_pin=14)

buzzer = Pin(32, Pin.OUT)
pwm_buzzer = PWM(buzzer)
pwm_buzzer.freq(1000)
pwm_buzzer.duty(512)

buzzer_on = False

while True:
    distance = ultrasonic_sensor.distance_cm()
    print("Distance: {:.2f} cm".format(distance))
    
    if distance < 100:
        if not buzzer_on:
            pwm_buzzer.duty(512)
            buzzer_on = True

        frequency = max(500, min(2000, 2000 - int(distance * 30)))
        pwm_buzzer.freq(frequency)
        print(f"Obstacle detected! Buzzer frequency: {frequency} Hz")
    else:
        if buzzer_on:
            pwm_buzzer.duty(0)
            buzzer_on = False
        print("No obstacle. Buzzer OFF")
    
    time.sleep(0.1)