from machine import *
from time import *

trig=Pin(9,Pin.OUT)
echo=Pin(10,Pin.IN)

LED=Pin(13,Pin.OUT)

buzzer=PWM(Pin(18))
buzzer.freq(1000)

LDR=ADC(Pin(26))
LDR_threshold= 2000

while True:
  Light_value=LDR.read_u16()
  print("LDR:",Light_value)

  if Light_value < LDR_threshold:
 print("DAY MODE_system idle")
     LED.value(0)
     buzzer.duty_u16(0)
     sleep(0.2)
     continue

  print("NIGHT MODE ON") 
     trig.value(0)
     sleep_us(2)
     trig.value(1)
     sleep_us(10)
     trig.value(0)

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

  print("distance",distance,"cm")
  if distance>50:
    print("NO PERSON NEAR")
    LED.value(0)
    buzzer.duty_u16(0)

  elif distance>20 and distance<=50:
    print("WELCOME LIGHT")
    LED.value(1)
    buzzer.duty_u16(0)

  elif distance<=20:
    print("SECURITY ALERT")
    LED.value(1)
    buzzer.duty_u16(20000)

sleep(0.1)