The circuitry and hardware for our project was rather simple. We had five total buttons, one for on/off toggle and four for the passcode entry. One pin on each button was connected to Vcc on the A3BU and another pin was connected to separate digital pins on the A3BU, then went through a pull down resistor to ground. The passive buzzer has two pins, one connected to the A3BU and one connected to ground. The two LED status lights were connected to ground on one pin, and the other pins were connected to separate pins on the A3BU after going through a resistor. Finally, the photo interrupter had one pin to Vcc, one pin to ground, and the final pin to a digital pin on the A3BU. After the project was functional, we trimmed down the circuit and made it a lot neater. You can see this in the image below. The final image is the circuit schematic for the project.