from machine import Pin, time_pulse_us
import time

# Define pins
TRIG = Pin(21, Pin.OUT)
ECHO = Pin(27, Pin.IN)
LED = Pin(18, Pin.OUT)

def get_distance():
    # Send a short trigger pulse
    TRIG.low()
    time.sleep_us(2)
    TRIG.high()
    time.sleep_us(10)
    TRIG.low()

    # Measure the duration of the echo pulse
    duration = time_pulse_us(ECHO, 1, 30000)  # 30ms timeout
    distance = (duration * 0.0343) / 2  # Distance in cm
    return distance

while True:
    dist = get_distance()
    print("Measured Distance = %.2f cm" % dist)

    # LED control
    if dist < 100:
        LED.value(1)
    else:
        LED.value(0)
    
    time.sleep(1)