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

# === CONFIGURATION ===
TRIGGER_PIN = 26
ECHO_PIN = 25
MAX_DISTANCE_CM = 500
ECHO_TIMEOUT_US = MAX_DISTANCE_CM * 2 * 29.1  # time for max range

# === SETUP PINS (initialized once) ===
trigger = Pin(TRIGGER_PIN, Pin.OUT)
echo = Pin(ECHO_PIN, Pin.IN)

def check_distance():
    trigger.value(0)
    sleep_us(2)
    # Send 10µs pulse
    trigger.value(1)
    sleep_us(10)
    trigger.value(0)

    try:
        pulse_time = time_pulse_us(echo, 1, int(ECHO_TIMEOUT_US))
        return pulse_time
    except OSError as ex:
        if ex.args[0] == 110:  # timeout
            raise OSError("Out of range")
        raise ex


def distance_mm():
    """Return distance in millimeters."""
    pulse_time = check_distance()
    return pulse_time * 100 // 582  # ~ (pulse_time / 5.82)


def distance_cm():
    """Return distance in centimeters."""
    pulse_time = check_distance()
    return (pulse_time / 2) / 29.1


# === USAGE EXAMPLE ===
while True:
    try:
        d_cm = distance_cm()
        print(f"Distance: {d_cm:.2f} cm")
    except OSError as e:
        print("Error:", e)
    sleep(0.5)