from machine import Pin, ADC, time_pulse_us
import time

# --- PIR Sensor ---
pir = Pin(27, Pin.IN)

# --- Ultrasonic Sensor ---
TRIG_PIN = 5
ECHO_PIN = 18
trig = Pin(TRIG_PIN, Pin.OUT)
echo = Pin(ECHO_PIN, Pin.IN)

# --- MQ-2 Gas Sensor (Analog) ---
mq2 = ADC(Pin(34))
mq2.atten(ADC.ATTN_11DB)
mq2.width(ADC.WIDTH_10BIT)  # 0–1023

# --- LED + Buzzer Alarm ---
led = Pin(2, Pin.OUT)    # Built-in LED (GPIO2)
buzzer = Pin(4, Pin.OUT) # External buzzer on GPIO4

# --- Ultrasonic Distance Function ---
def get_distance():
    trig.off()
    time.sleep_us(2)
    trig.on()
    time.sleep_us(10)
    trig.off()
    duration = time_pulse_us(echo, 1, 30000)
    distance = (duration / 2) * 0.0343
    return distance

print("Smart Security Alarm System ")
time.sleep(2)

while True:
    motion = pir.value()         # 1 = motion detected
    distance = get_distance()    # cm
    gas_value = mq2.read()       # 0–1023

    print("Motion:", motion, " Distance:", distance, "cm Gas:", gas_value)

    if motion == 1:
        print(" Motion Detected ")
        for i in range(3):
            led.on(); buzzer.on()
            time.sleep(0.2)
            led.off(); buzzer.off()
            time.sleep(0.2)

    if distance < 30:
        print(" A person near by door")
        for i in range(3):
            led.on(); buzzer.on()
            time.sleep(0.2)
            led.off(); buzzer.off()
            time.sleep(0.2)

    if gas_value > 600:
        print(" Gas/Smoke Detected")
        for i in range(3):
            led.on(); buzzer.on()
            time.sleep(0.2)
            led.off(); buzzer.off()
            time.sleep(0.2)

    if motion == 0 and distance >= 30 and gas_value <= 600:
        print("System Normal")
        led.off()
        buzzer.off()

    time.sleep(1)