from machine import Pin, PWM
from utime import sleep_us, ticks_us, sleep

red_pin = Pin(23, Pin.OUT)
yellow_pin = Pin(22, Pin.OUT)
green_pin = Pin(19, Pin.OUT)

trigger = Pin(25, Pin.OUT)
echo = Pin(33, Pin.IN)

def ultra():
    trigger.off()
    sleep_us(2)
    trigger.on()
    sleep_us(5)
    trigger.off()
    while echo.value() == 0:
        signal_off = ticks_us()
    while echo.value() == 1:
        signal_on = ticks_us()
    try:
        time_pass = signal_on - signal_off
    except NameError:
        return 0
    return time_pass/58
    
while True:
    dist = ultra()
    print(f'Distance: {dist:.1f}cm')
    sleep(0.1)
    if dist <=50:
        buzzer=PWM(Pin(27),freq=1000,duty=512)
        red_pin.on()
        yellow_pin.off()
        red_pin.off()
    elif dist <=100:
        buzzer=PWM(Pin(27),freq=600,duty=512)
        red_pin.off()
        green_pin.off()
        yellow_pin.on()
    elif dist <=200:
        buzzer=PWM(Pin(27),freq=300,duty=0)
        yellow_pin.off()
        red_pin.off()
        green_pin.on()
    else:
        buzzer=PWM(Pin(27),freq=100,duty=0)
        yellow_pin.off()
        red_pin.off()
        green_pin.off()