from machine import Pin, time_pulse_us
import time

# Setup pins
pir = Pin(15, Pin.IN)
trig = Pin(4, Pin.OUT)
echo = Pin(5, Pin.IN)
led = Pin(13, Pin.OUT)

def get_distance():
    # Send a 10us pulse to trigger ultrasonic
    trig.off()
    time.sleep_us(2)
    trig.on()
    time.sleep_us(10)
    trig.off()

    # Measure echo pulse width in microseconds
    duration = time_pulse_us(echo, 1, 30000)  # timeout 30ms

    # Calculate distance (speed of sound = 34300 cm/s)
    # Distance = (duration / 2) / 29.1
    distance = (duration / 2) / 29.1
    return distance

def blink_led(times, delay_ms):
    for _ in range(times):
        led.on()
        time.sleep_ms(delay_ms)
        led.off()
        time.sleep_ms(delay_ms)

while True:
    if pir.value() == 1:
        # Motion detected by PIR
        distance = get_distance()
        print("Motion detected! Distance:", distance, "cm")
        if distance < 20 and distance > 0:
            # Intruder alert - blink LED rapidly
            for _ in range(10):
                led.on()
                time.sleep(0.1)
                led.off()
                time.sleep(0.1)
        else:
            # No close object detected, LED off
            led.off()
    else:
        # No motion, LED off
        led.off()

    time.sleep(0.2)