from machine import Pin, time_pulse_us
import time

# Pin configuration
trig_pin = Pin(21, Pin.OUT)
echo_pin = Pin(20, Pin.IN)
led1 = Pin(1, Pin.OUT)
led2 = Pin(2, Pin.OUT)
led3 = Pin(3, Pin.OUT)
Bp = Pin(19, Pin.OUT)
buzzer = Pin(18, Pin.OUT)
def measure_distance():
    trig_pin.value(0)
    time.sleep_us(2)
    trig_pin.value(1)
    time.sleep_us(10)
    trig_pin.value(0)
    
    duration = time_pulse_us(echo_pin, 1)
    distance = (duration * 0.0343) / 2  # cm
    return distance

def led_blink_cycle(distance):
    delay = max(100, min(1000, int(2000 / (distance / 200))))  # 100 ms min, 1000 ms max
    while True:
        led1.value(1)
        time.sleep_ms(delay)
        led1.value(0)

        led2.value(1)
        time.sleep_ms(delay)
        led2.value(0)

        led3.value(1)
        time.sleep_ms(delay)
        led3.value(0)

while True:
    distance = measure_distance()
    if distance <= 200:
        led_blink_cycle(distance)
    else:
        buzzer.value(1)
        time.sleep(0.5)
        buzzer.value(0)