from machine import *
from time import *

trig = Pin(27,Pin.OUT)
echo = Pin(26,Pin.IN)
rled = Pin(4,Pin.OUT)
gled = Pin(6,Pin.OUT)
buzzer = PWM(Pin(9))
buzzer.freq(500)

while True:
    trig.value(0)
    sleep_us(2)
    trig.value(1)
    sleep_us(10)
    trig.value(0)

    duration = time_pulse_us(echo,1)
    distance = (duration*0.0343)/2
    print("duration is", duration,"distance is", distance)
    
    if distance<20:
        buzzer.duty_u16(20000)
        for count in range(0,10):
            rled.value(1)
            sleep(0.5)
            rled.value(0)
            sleep(0.5)
            
    elif distance>20 and distance<=100:
        buzzer.duty_u16(0)
        rled.value(1)
        gled.value(0)
    
    else:
        gled.value(1)
        rled.value(0)
        
sleep (0.5)