from machine import Pin, PWM, time_pulse_us
import time

trig = Pin(5, Pin.OUT)
echo = Pin(17, Pin.IN)
servo = PWM(Pin(18), freq=50)

print("System Active! Click the ultrasonic sensor and move the slider.")

while True:
    # Trigger sensor
    trig.off()
    time.sleep_us(2)
    trig.on()
    time.sleep_us(10)
    trig.off()
    
    # Calculate distance
    duration = time_pulse_us(echo, 1, 30000)
    distance = (duration * 0.0343) / 2
    
    # Print reading to terminal to debug
    print(f"Current Distance: {distance:.1f} cm")
    
    # Gate Action
    if 0 < distance < 50:
        print("-> GATE OPENING")
        servo.duty(123)
        time.sleep(3)
    else:
        servo.duty(26)
        
    time.sleep(0.4)