import time
import board
import digitalio
import pulseio

# Set up pins
TRIG = digitalio.DigitalInOut(board.GP4)
TRIG.direction = digitalio.Direction.OUTPUT
LED = digitalio.DigitalInOut(board.GP13)
LED.direction = digitalio.Direction.OUTPUT

# Threshold
DISTANCE_THRESHOLD = 100  # Distance in cm

# Function to control LED based on distance
def led_alert(LED, distance):
    if distance <= DISTANCE_THRESHOLD:
        LED.value = True  # Turn LED on
    else:
        LED.value = False  # Turn LED off

# Function to send pulse and measure response
def send():
    TRIG.value = False
    time.sleep(0.000002)
    TRIG.value = True
    time.sleep(0.00001)
    TRIG.value = False

    # Measure pulse duration with PulseIn, using board.GP5 directly
    pulse = pulseio.PulseIn(board.GP5, maxlen=1, idle_state=False)
    while len(pulse) == 0:
        pass
    pulse_width = pulse[0]
    pulse.deinit()  # Deinitialize to free up resources

    return pulse_width

# Main loop
while True:
    pulse_width = send()
    distance = pulse_width * 0.034 / 2  # Calculate distance in cm
    
    led_alert(LED, distance)
    print("Distance:", distance, "cm")
    time.sleep(1)