from machine import Pin, time_pulse_us, PWM
import time

trig = Pin(3, Pin.OUT)
echo = Pin(2, Pin.IN)

red = Pin(10, Pin.OUT)
green = Pin(11, Pin.OUT)

buzzer = PWM(Pin(15))

def get_distance():
    trig.low()
    time.sleep_us(2)
    trig.high()
    time.sleep_us(10)
    trig.low()

    duration = time_pulse_us(echo, 1)
    distance = (duration * 0.0343) / 2
    return distance

while True:
    dist = get_distance()
    print(dist)

    if dist < 20:
        # NEAR → RED
        red.value(1)
        green.value(0)

        buzzer.freq(2000)
        buzzer.duty_u16(30000)

    else:
        # FAR → GREEN
        red.value(0)
        green.value(1)

        buzzer.freq(500)
        buzzer.duty_u16(15000)

    time.sleep(0.2)