from machine import Pin, PWM, time_pulse_us
import time

TRIG = Pin(5, Pin.OUT)
ECHO = Pin(18, Pin.IN)

servo = PWM(Pin(13), freq=50)

def open_gate():
    servo.duty(115)   # ~90 degrees (open)

def close_gate():
    servo.duty(40)    # 0 degrees (closed)

def get_distance_cm():
    TRIG.value(0)
    time.sleep_us(2)
    TRIG.value(1)
    time.sleep_us(10)
    TRIG.value(0)

    duration = time_pulse_us(ECHO, 1, 30000)
    if duration < 0:
        return None

    distance = (duration * 0.0343) / 2
    return distance

close_gate()

while True:
    dist = get_distance_cm()

    if dist is not None:
        print("Distance:", dist, "cm")
        if dist < 10:
            print("Object detected - opening gate")
            open_gate()
            time.sleep(3)
            close_gate()

    time.sleep(0.5)