from machine import Pin
import time

# HC-SR04 pins
TRIG = Pin(3, Pin.OUT)
ECHO = Pin(2, Pin.IN)

# Buzzer
BUZZER = Pin(15, Pin.OUT)

def measure_distance():
    # Make sure trigger is LOW
    TRIG.value(0)
    time.sleep_us(2)

    # Send 10 us trigger pulse
    TRIG.value(1)
    time.sleep_us(10)
    TRIG.value(0)

    # Measure echo pulse
    duration = time.ticks_us()

    while ECHO.value() == 0:
        duration = time.ticks_us()

    start = duration

    while ECHO.value() == 1:
        duration = time.ticks_us()

    end = duration

    # Calculate distance in cm
    pulse_time = time.ticks_diff(end, start)
    distance = (pulse_time * 0.0343) / 2

    return distance


while True:
    distance = measure_distance()

    print("Distance:", round(distance, 2), "cm")

    if distance <= 100:
        BUZZER.value(1)
    else:
        BUZZER.value(0)

    time.sleep(0.2)