from machine import Pin, PWM
import time

trigger_pin = Pin(5, Pin.OUT)
echo_pin = Pin(18, Pin.IN)
buzzer_pin = PWM(Pin(2))

def get_distance():
    # Send a short pulse to trigger the measurement
    trigger_pin.off()
    time.sleep_us(2)
    trigger_pin.on()
    time.sleep_us(10)
    trigger_pin.off()

    # Measure the echo duration
    while echo_pin.value() == 0:
        pulse_start = time.ticks_us()

    while echo_pin.value() == 1:
        pulse_end = time.ticks_us()

    pulse_duration = time.ticks_diff(pulse_end, pulse_start)
    # Calculate the distance in cm
    distance = pulse_duration * 0.034 / 2
    return distance

def buzz(frequency):
    buzzer_pin.freq(frequency)
    buzzer_pin.duty(512)  # Set duty cycle to 50% for sound

def stop_buzz():
    buzzer_pin.duty(0)  # No sound

while True:
    distance = get_distance()
    print(f"Distance: {distance:.2f} cm")

    if distance < 20:
        buzz(1000)  # Buzz at 1000 Hz
    elif distance < 50:
        buzz(2000)  # Buzz at 2000 Hz
    else:
        stop_buzz()  # No sound

    time.sleep(0.1)  # Delay for 100ms