2024 Business Card Challenge: Go Tic-Tac-Toe-to-Toe With Them

A PCB business card that plays tic-tac-toe with red and blue LEDs.

There is perhaps no more important time to have a business card than when you’re in college, especially near the end when you’re applying for internships and such. And it’s vital that you stand out from the crowd somehow. To that end, Electrical & Computer Engineer [Ryan Chan] designed a tidy card that plays tic-tac-toe.

Instead of X and O, the players are indicated by blue and red LEDs. Rather than having a button at every position, there is one big control button that gets pressed repeatedly until your LED is in the desired position, and then you press and hold to set it and switch control to the other player. In addition to two-player mode, the recipient of your card can also play alone against the ATMega.

The brains of this operation is an ATMega328P-AU with the Arduino UNO bootloader for ease of programming. Schematic and code are available if you want to make your own, but we suggest implementing some type of changes to make it your own. Speaking of, [Ryan]  has several next steps in mind, including charlieplexing the LEDs, using either USB-C or a coin cell for power, upgrading the AI, and replacing the control button with a capacitive pad or two. Be sure to check it out in action in the two videos after the break.

4 thoughts on “2024 Business Card Challenge: Go Tic-Tac-Toe-to-Toe With Them

    1. Incredibly small current/voltage, I doubt it’ll be easy to detect without any additional circuitry. Also when pressing an LED, its likely your hand would be present over other LEDs which you do not want to “activate”.

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