from machine import Pin, time_pulse_us
from time import sleep_us, sleep
from utime import sleep

# Define the GPIO pin numbers for the trigger and echo pins.
ECHO_PIN = 13
TRIGGER_PIN = 1

led1 = Pin(28,Pin.OUT)
led2 = Pin(27,Pin.OUT)
led3 = Pin(26,Pin.OUT)

# Initialize trigger and echo pins.
trigger = Pin(TRIGGER_PIN, Pin.OUT)
echo = Pin(ECHO_PIN, Pin.IN)

def measure_distance():
    # Ensure trigger is low initially.
    trigger.low()
    sleep_us(2)

    # Send a 10 microsecond pulse to the trigger pin.
    trigger.high()
    sleep_us(10)
    trigger.low()

    # Measure the duration of the echo pulse (in microseconds).
    pulse_duration = time_pulse_us(echo, Pin.high)

    # Calculate the distance (in centimeters) using the speed of sound (343m/s).
    distance = pulse_duration * 0.0343 / 2
    return distance

def main():
    while True:
        # Measure the distance and print the value in centimeters.
        distance = measure_distance()
        print("Distance: {:.2f} cm".format(distance))
        if(0<=distance<100):
            led1.on()
            led2.off()
            led3.off()
        elif(10<=distance<200):
            led1.off()
            led2.on()
            led3.off()
        elif(200<=distance):
            led1.off()
            led2.off()
            led3.on()
        
        # Wait for 1 second before taking the next measurement.
        sleep(1)

if __name__ == "__main__":
    main()