import machine
import utime

# GPIO Pin assignments
TRIG_PIN = 15  # GPIO Pin for Trigger
ECHO_PIN = 14  # GPIO Pin for Echo
BUZZER_PIN = 16  # GPIO Pin for Buzzer

# Set up GPIO pins
trigger = machine.Pin(TRIG_PIN, machine.Pin.OUT)
echo = machine.Pin(ECHO_PIN, machine.Pin.IN)
buzzer = machine.Pin(BUZZER_PIN, machine.Pin.OUT)

# Function to measure distance using the Ultrasonic Distance Sensor
def measure_distance():
    # Send a trigger pulse
    trigger.off()  # Set trigger pin low
    utime.sleep_us(2)
    trigger.on()   # Set trigger pin high
    utime.sleep_us(10)
    trigger.off()  # Set trigger pin low

    # Measure the duration of the echo pulse
    while echo.value() == 0:
        pulse_start = utime.ticks_us()
    while echo.value() == 1:
        pulse_end = utime.ticks_us()

    # Calculate distance from pulse duration
    pulse_duration = utime.ticks_diff(pulse_end, pulse_start)
    speed_of_sound = 34300  # Speed of sound in cm/s
    distance = (pulse_duration * speed_of_sound) / 2 / 1000000  # Convert to meters
    return distance

# Set minimum distance threshold for buzzer activation (in cm)
MIN_DISTANCE_THRESHOLD = 20

# Continuously acquire distance measurements while the board has power
while True:
    distance_cm = measure_distance() * 100  # Convert to cm
    print("Distance: {:.2f} cm".format(distance_cm))

    # Check if distance is below the threshold for buzzer activation
    if distance_cm < MIN_DISTANCE_THRESHOLD:
        buzzer.on()  # Turn on the buzzer
    else:
        buzzer.off()  # Turn off the buzzer

    utime.sleep(0.1)