from machine import Pin
from time import sleep

# Inputs
# A = Door sensor
# B = Window sensor
# C = Security system armed

A_btn = Pin(18, Pin.IN, Pin.PULL_UP)
B_btn = Pin(19, Pin.IN, Pin.PULL_UP)
C_btn = Pin(21, Pin.IN, Pin.PULL_UP)

# Outputs
or_led = Pin(4, Pin.OUT)   # Shows A OR B
alarm_led = Pin(2, Pin.OUT) # Shows final output Y

last_state = None

print("======================================")
print(" Combinational Circuit Design Lab")
print(" Alarm = Armed AND (Door OR Window)")
print(" Boolean Expression: Y = C AND (A OR B)")
print("======================================")
print()
print("A = Door sensor")
print("B = Window sensor")
print("C = System armed")
print("Y = Alarm")
print()
print("Press the buttons and observe the LEDs.")
print("Yellow LED = A OR B")
print("Red LED    = Final Alarm Output Y")
print()
print("C A B | A_OR_B | Y")
print("-------------------")

while True:
    # Because buttons use PULL_UP:
    # Not pressed = 1 electrically, so we invert it.
    # Pressed = logical 1
    A = 1 if A_btn.value() == 0 else 0
    B = 1 if B_btn.value() == 0 else 0
    C = 1 if C_btn.value() == 0 else 0

    # Step 4 and 5:
    # Boolean Expression:
    # Y = C AND (A OR B)

    A_OR_B = A or B
    Y = C and A_OR_B

    or_led.value(A_OR_B)
    alarm_led.value(Y)

    current_state = (C, A, B, A_OR_B, Y)

    if current_state != last_state:
        print(C, A, B, "|   ", int(A_OR_B), "   |", int(Y))
        last_state = current_state

    sleep(0.1)