from machine import Pin, PWM
import utime

TRIG = Pin(3, Pin.OUT)
ECHO = Pin(2, Pin.IN)
led = PWM(Pin(15)) 
led.freq(1000)  

def get_distance():
    TRIG.low()
    utime.sleep_us(2)
    TRIG.high()
    utime.sleep_us(10)
    TRIG.low()

    signal_off = utime.ticks_us()  # Initialize to avoid errors
    signal_on = utime.ticks_us()

    while ECHO.value() == 0:
        signal_off = utime.ticks_us()
    while ECHO.value() == 1:
        signal_on = utime.ticks_us()

    time_passed = signal_on - signal_off
    distance = (time_passed * 0.0343) / 2  # Convert to cm
    return distance

while True:
    dist = get_distance()
    print("Distance:", dist, "cm")

    if dist > 100:
        brightness = 0  
    else:
        brightness = int((1 - (dist / 100)) * 65535)  

    led.duty_u16(brightness)  
    utime.sleep(0.1)