from machine import Pin, PWM
import time

# Pin definitions
LED_PIN = 15  # GPIO pin for the LED
TRIGGER_PIN = 26  # GPIO pin connected to the trigger pin of ultrasonic sensor
ECHO_PIN = 25     # GPIO pin connected to the echo pin of ultrasonic sensor

# Setup LED
led = Pin(LED_PIN, Pin.OUT)

# Setup ultrasonic sensor
trigger = Pin(TRIGGER_PIN, Pin.OUT)
echo = Pin(ECHO_PIN, Pin.IN)

# Function to measure distance using ultrasonic sensor
def measure_distance():
    # Send a pulse to trigger the sensor
    trigger.value(1)
    time.sleep_us(10)
    trigger.value(0)
    
    # Wait for the echo pin to go high
    while echo.value() == 0:
        pulse_start = time.ticks_us()
    
    # Wait for the echo pin to go low
    while echo.value() == 1:
        pulse_end = time.ticks_us()
    
    # Calculate pulse duration
    pulse_duration = time.ticks_diff(pulse_end, pulse_start)
    
    # Calculate distance (in cm) based on the speed of sound
    distance_cm = (pulse_duration * 0.0343) / 2
    
    return distance_cm

# Main loop
while True:
    # Measure distance
    distance = measure_distance()
    
    # Toggle LED based on distance
    if distance < 10:  # If object is closer than 10cm
        led.value(1)  # Turn on LED
    else:
        led.value(0)  # Turn off LED
    
    # Print distance
    print("Distance:", distance, "cm")
    
    # Delay before next measurement
    time.sleep(1)