from machine import Pin, time_pulse_us
import time

# Define GPIO pins
PIN_TRIGGER = Pin(4, Pin.OUT)
PIN_ECHO = Pin(17, Pin.IN)

def measure_distance():
    # Ensure the trigger is low
    PIN_TRIGGER.value(0)
    time.sleep_us(2)
    
    # Send a 10-microsecond pulse
    PIN_TRIGGER.value(1)
    time.sleep_us(10)
    PIN_TRIGGER.value(0)
    
    # Measure the duration of the echo pulse
    pulse_duration = time_pulse_us(PIN_ECHO, 1, 30000)  # Timeout after 30ms
    
    # If no echo pulse detected, return None
    if pulse_duration < 0:
        return None
    
    # Calculate distance (cm)
    distance = (pulse_duration * 0.0343) / 2
    return round(distance, 2)

try:
    print("Waiting for sensor to settle")
    time.sleep(2)  # Allow sensor to stabilize
    
    while True:
        print("Calculating distance...")
        distance = measure_distance()
        if distance is None:
            print("No echo received. Try again.")
        else:
            print(f"Distance: {distance} cm")
        time.sleep(1)

except KeyboardInterrupt:
    print("Measurement stopped by user.")