from machine import Pin, time_pulse_us
import time

# Setup the ultrasonic sensor
trigger = Pin(5, Pin.OUT)  # Trigger pin connected to GPIO 5
echo = Pin(18, Pin.IN)     # Echo pin connected to GPIO 18

# Setup the LED on GPIO 2
led = Pin(2, Pin.OUT)

def measure_distance():
    # Send a pulse
    trigger.value(0)
    time.sleep_us(2)
    trigger.value(1)
    time.sleep_us(10)
    trigger.value(0)
    
    # Measures the pulse duration
    duration = time_pulse_us(echo, 1)
    distance_cm = (duration / 2) / 29.1  # Convert to centimeters
    distance_m = distance_cm / 100       # Convert to meters
    
    return distance_m

def main():
    while True:
        distance = measure_distance()
        print("Distance:", distance, "m")
        
        if distance > 3.5:
            led.value(1)
            print("LED turned on")
        else:
            led.value(0)
        
        time.sleep(1)  # Wait for 1 second before the next measurement

if __name__ == "__main__":
    main()