PCB Custom Design - Contact Card with USB

During my third year in university I decided I would explore the world of PCB design, as I think a minimal grasp on the topic should be obligatory for any graduate in mechatronics.

I set out to make a custom namecard, which is a popular project online, and embed my CV into it. As the project evolved, I decided to include a little game within the card.

Objective:

1. To learn how to design a circuit and PCB

2. To build a PCB capable of playing a minigame by simply inserting it into a USB terminal.

3. To build a PCB with an abridged version of my CV imprinted on it.

Method:

I used EasyEDA, an online PCB design tool, to both design my circuit and the PCB itself. The reason for picking EasyEDA was twofold. Firstly, it included the entire JLCPCB catalog by default, and as a beginner I did not want to start by installing my own component libraries or god forbid make my own component symbols (which I have done in the past but wasn't necessary for this project). Secondly, it allows for the design to be automatically checked by JLCPCB's system so that you're sure you're not sending a circuit that won't work as intended once transferred to a PCB.

Final product:

The circuit is a relatively simple circuit. It uses an ATTiny85 for processing and memory. The ATTiny drives a series of LEDs placed on a ring. Since the ATTiny does not have enough outputs to individually address LEDs, I implemented a charlieplexing network (https://en.wikipedia.org/wiki/Charlieplexing). The LEDs light up in sequence, emulating a "firefly" flying around the ring. A thin button placed by one of the LEDs acts as a "catcher" - if the player presses the button right as the LED next to it lights up, congratulations! They have "caught" the firefly. The game then repeats, this time with the firefly flying by faster and faster.

Unfortunately, my soldering equipment is simply not suited to soldering such small pads. I needed a hot air station and time to practice, which I simply did not have.

However, I did account for this eventuality when designing the circuit, so I left some debugging pads at the bottom of the boards (in the first picture, bottom left corner of the boards) so that I could at least externally power the board and play the game. Here's a video!