from machine import Pin, PWM, time_pulse_us
import time 

trigger = Pin(13, Pin.OUT) 
echo = Pin(12, Pin.IN)    
led = Pin(5, Pin.OUT)    
alarm = PWM(Pin(12))    

distance_threshold = 20 

def measure_distance():
    trigger.off()
    trigger.on()
    trigger.off()
    pulse_time = time_pulse_us(echo, 1, 30000) 
    distance = (pulse_time / 2) / 29.1 
    return distance

while True:
    jarak = measure_distance()
    print("Jarak:", jarak, "cm")

    if jarak < distance_threshold:
        led.value(1)       
        alarm.freq(400)  
        alarm.duty(512)    
    else:
        led.value(0)        
        alarm.duty(0)