from machine import Pin, time_pulse_us
from gpio_lcd import GpioLcd
from time import sleep, sleep_us, sleep_ms

SOUND_SPEED=340 # sound speed in the air
TRIG_PULSE_DURATION_US=10

trig_pin = Pin(15, Pin.OUT) # Pico GP15 pin
echo_pin = Pin(14, Pin.IN)  # Pico GP14 pin

lcd = GpioLcd(rs_pin = Pin(0),
              enable_pin = Pin(1),
              d4_pin = Pin(2),
              d5_pin = Pin(3),
              d6_pin = Pin(4),
              d7_pin = Pin(5),
              num_lines = 2, num_columns = 16)

def us_sensor():
    trig_pin.value(0)
    sleep_us(5)
    # 10 µs impulse
    trig_pin.value(1)
    sleep_us(TRIG_PULSE_DURATION_US)
    trig_pin.value(0)
    ultrason_duration = time_pulse_us(echo_pin, 1, 30000) # Returns the propagation time of the wave. (µs)
    distance_cm = SOUND_SPEED * ultrason_duration / 20000
    return distance_cm

while True:
    dist_cm = us_sensor()
    lcd.move_to(0, 0)
    lcd.putstr("UltSnd Distance")
    lcd.move_to(0, 1)
    dist_fmt = "{0:.3f} cm".format(dist_cm)
    lcd.putstr(dist_fmt)
    print(f"Distance : {dist_cm} cm")
    sleep_ms(500)
    lcd.move_to(len(dist_fmt)-2,1)
    lcd.putstr("  ")