from machine import Pin, time_pulse_us
import time

# Define pins connected to the HC-SR04 sensor
trigger_pin = Pin(4, Pin.OUT)
echo_pin = Pin(5, Pin.IN)

# Function to measure distance from HC-SR04 sensor
def measure_distance():
    # Send a 10us pulse on the trigger pin to start the measurement
    trigger_pin.value(0)
    time.sleep_us(2)
    trigger_pin.value(1)
    time.sleep_us(10)
    trigger_pin.value(0)

    # Measure the duration of the echo pulse on the echo pin
    duration = time_pulse_us(echo_pin, 1, 30000)  # Timeout of 30ms (30,000 microseconds)
    
    # Calculate distance using the speed of sound (343 m/s)
    # Divide by 2 because the sound wave travels to the object and back
    distance = duration * 0.0343 / 2

    return distance

# Main loop
while True:
    # Measure distance from HC-SR04 sensor
    distance = measure_distance()

    # Print distance
    print("Distance: {:.2f} cm".format(distance))

    # Wait for a short period
    time.sleep(1)