from machine import Pin, time_pulse_us
import time

# Pin setup
TRIG = Pin(17, Pin.OUT)  # Trigger pin for HC-SR04
ECHO = Pin(16, Pin.IN)   # Echo pin for HC-SR04
BUZZER = Pin(18, Pin.OUT)  # Buzzer pin

def get_distance():
    """
    Measures the distance using the HC-SR04 sensor.
    Returns distance in meters.
    """
    # Send a 10us pulse to trigger
    TRIG.low()
    time.sleep_us(2)
    TRIG.high()
    time.sleep_us(10)
    TRIG.low()
    
    # Measure the duration of the echo pulse
    duration = time_pulse_us(ECHO, 1, 30000)  # Wait for high, timeout after 30ms
    
    # Convert duration to distance in meters (speed of sound = 343 m/s)
    distance = (duration / 2) * 0.000343
    return distance

try:
    while True:
        distance = get_distance()  # Measure distance
        print(f"Distance: {distance:.2f} meters")  # Print distance for debugging
        
        if distance >= 3.0:
            # Beep the buzzer for distances 3m or greater
            BUZZER.high()
            time.sleep(0.2)
            BUZZER.low()
            time.sleep(0.2)
        elif distance <= 1.0:
            # Turn off the buzzer for distances 1m or less
            BUZZER.low()
        
        time.sleep(0.1)  # Small delay for sensor stability
except KeyboardInterrupt:
    print("Program stopped by user")
    BUZZER.low()  # Ensure the buzzer is off when exiting