from machine import Pin, I2C, PWM  #PWM = Pulse Width Modulation
import time
import ssd1306

#Initialize I2C for OLED
i2c = I2C(0, scl=Pin(22), sda=Pin(21))
oled = ssd1306.SSD1306_I2C(128, 64, i2c)

trig_pin = Pin(5, Pin.OUT)     #Trigger pin for ultrasonic sensor
echo_pin = Pin(18, Pin.IN)     #Echo pin for ultrasonic sensor
pir_pin = Pin(17, Pin.IN)      #PIR motion sensor pin
led_green = Pin(32, Pin.OUT)   #Green LED pin
led_yellow = Pin(25, Pin.OUT)  #Yellow LED pin
led_red = Pin(27, Pin.OUT)     #Red LED pin
buzzer = PWM(Pin(23), freq=1000, duty=0)  #Buzzer pin with PWM


pir_motion_detected = False

def get_distance():
    trig_pin.value(1)
    time.sleep_us(10)
    trig_pin.value(0)

    #Measure the echo time
    pulse_start = time.ticks_us()
    while echo_pin.value() == 0:
        pulse_start = time.ticks_us()
    while echo_pin.value() == 1:
        pulse_end = time.ticks_us()

    pulse_duration = pulse_end - pulse_start
    distance = (pulse_duration * 0.034) / 2
    return distance

def display_message(distance, status1, status2):
    oled.fill(0)
    oled.text(f"Distance: {distance:.1f} cm", 0, 0) #Line 1
    oled.text(status1, 0, 21) #Line 2
    oled.text(status2, 0, 42) #Line 3
    oled.show()

def beep(times):
    for _ in range(times):
        buzzer.duty(512)  
        time.sleep(0.1)   
        buzzer.duty(0)    
        time.sleep(0.1)  

def pir_handler(pin):
    global pir_motion_detected
    pir_motion_detected = pin.value() == 1


pir_pin.irq(trigger=Pin.IRQ_RISING | Pin.IRQ_FALLING, handler=pir_handler)

while True:
    distance = get_distance()

    if distance <= 100:
        led_red.value(1)
        led_yellow.value(0)
        led_green.value(0)
        buzzer.duty(512) #Buzzer on continously
        display_message(distance, " CRITICAL AREA!", "    DANGER!!")

    elif 101 <= distance <= 250:
        led_red.value(0)
        led_yellow.value(1)
        led_green.value(0)
        buzzer.duty(0)

        if pir_motion_detected:
            beep(2) #Buzzer beep 2 times
        display_message(distance, " Animal entered", " CAUTION ZONE!!")

    else:
        led_green.value(1)
        led_yellow.value(0)
        led_red.value(0)
        buzzer.duty(0)
        display_message(distance, "  Animal is in", "   SAFE ZONE")

    time.sleep(1)