from machine import Pin, PWM
import utime

# Pin definition
relay1_pin = 14
relay2_pin = 15
lpg_detector_pin = 12
fire_detector_pin = 13
trigger_pin = 10
echo_pin = 11
led_pin = 16

# GPIO pins setup
relay1 = Pin(relay1_pin, Pin.OUT)
relay2 = Pin(relay2_pin, Pin.OUT)
lpg_detector = Pin(lpg_detector_pin, Pin.IN)
fire_detector = Pin(fire_detector_pin, Pin.IN)
trigger = Pin(trigger_pin, Pin.OUT)
echo = Pin(echo_pin, Pin.IN)
red_led = Pin(led_pin, Pin.OUT)

# Sound an alarm (using a PWM pin for now, connect to a buzzer)
alarm = PWM(Pin(2))

def sound_alarm(frequency):
    alarm.freq(frequency) # 1kHz frequency
    alarm.duty_u16(512) # 50% duty cycle

def stop_alarm(): # Stop the alarm
    alarm.deinit()

def read_distance():
    # this function will read distance from distance sensor
    trigger.low()
    utime.sleep_us(2)
    trigger.high()
    utime.sleep_us(5)
    trigger.low()
    while echo.value() == 0:# Wait until we get sound back on echo pin
        pass
    start = utime.ticks_us() # note down current receiving time
    while echo.value() == 1: # Wait until we are getting sound signal back
        pass
    end = utime.ticks_us() # note down the time 
    distance = (end - start) / 2 / 29.1 # Calculate distance in cm
    return distance

while True:
    # Relay Control
    relay1.high() # turn on relay
    relay2.low() # turn off relay
    utime.sleep(1)

    relay1.low() # turn off relay
    relay2.high() # turn on relay
    utime.sleep(1)

    # LPG & Fire Detection if signal is high
    if lpg_detector.value():
        sound_alarm(420)
    elif fire_detector.value():
        sound_alarm(840)
    else:
        stop_alarm()

    # Distance Sensor Check
    print("Distance:", read_distance())
    if read_distance() < 50: # if anything gets in this distance turn on red led
        red_led.high()
    else:
        red_led.low()
        utime.sleep(0.1)