import machine 
from machine import Pin, PWM 
import time 
 
# Configure pins 
trigger_pin = Pin(12, Pin.OUT) 
echo_pin = Pin(14, Pin.IN) 
led_pin = PWM(Pin(13), freq=5000, duty=0) 
 
while True: 
    # Trigger ultrasonic sensor 
    trigger_pin.value(0) 
    time.sleep_us(2) 
    trigger_pin.value(1) 
    time.sleep_us(10) 
    trigger_pin.value(0) 
 
    # Measure distance 
    duration = machine.time_pulse_us(echo_pin, 1) 
    distance = duration / 58.2 
 
    # Adjust LED brightness based on distance 
    duty_cycle = int((distance/400)*1022) 
    led_pin.duty(duty_cycle) 
 
    # Wait a short time before measuring again 
    time.sleep(0.1)