from machine import Pin, PWM
import time

# Initialize components
buzzer = PWM(Pin(19))  # Passive buzzer on GPIO 19
led_detection = Pin(21, Pin.OUT)  # Detection LED on GPIO 21
#led_object = Pin(27, Pin.OUT)  # Object LED on GPIO 27
trig = Pin(25, Pin.OUT)  # Trig pin for ultrasonic sensor on GPIO 25
echo = Pin(26, Pin.IN)   # Echo pin for ultrasonic sensor on GPIO 26

# Function to play a tone on the buzzer
def play_tone(frequency, duration):
    buzzer.freq(frequency)  # Set frequency
    buzzer.duty_u16(512)    # 50% duty cycle
    time.sleep(duration)    # Play for the duration
    buzzer.duty_u16(0)      # Stop the buzzer

# Function to measure distance using the ultrasonic sensor
def measure_distance():
    trig.off()
    time.sleep_us(2)
    trig.on()
    time.sleep_us(10)
    trig.off()

    # Measure the duration of the echo pulse
    while echo.value() == 0:
        pass
    start_time = time.ticks_us()

    while echo.value() == 1:
        pass
    end_time = time.ticks_us()

    # Calculate distance (duration * speed of sound / 2)
    duration = time.ticks_diff(end_time, start_time)
    distance = (duration / 2) / 29.1  # Convert to cm
    return distance

# Test loop
while True:
    distance = measure_distance()
    print("Distance:", distance, "cm")

    if distance < 10:  # Object detected within 10 cm
        play_tone(1000, 0.1)  # Beep buzzer
        led_detection.value(1)  # Turn ON detection LED
        #led_object.value(1)     # Turn ON object LED
    else:
        led_detection.value(0)  # Turn OFF detection LED
        #led_object.value(0)     # Turn OFF object LED
    
    time.sleep(0.5)  # Wait before the next measurement