Description
The project is a physical implementation of the game Tic Tac Toe. Additionally, a speaker will play music in the background for better ambiance, there will be a buzzer to introduce a time limit for each move; it will signal when the player has 5 seconds left. Also, there will be a LED strip for a better visual effect.

Motivation
I think this is a fun game that I always used to play as a kid, so it's an additional motivation for me to implement it. It's simple, yet effective, and the fact that I can have „a pocket version” of it would mean a lot to me.

I used two Arduino UNO R3 as µCs. For inputs, I will have a keyboard with four buttons for moving around the Tic Tac Toe grid and an additional button for selecting in which tile a symbol will go. The music will be played using microSD card reader for the input and a speaker for the output. A buzzer will also be used to signal the last five seconds until the player will have to make a move and the LED Strip will be used for visual enhancement. Finally, an LCD will be used to display the actual game.

Materials:
2 x Arduino UNO R3
2 x mini breadboard
1 x button
1 x keyboard with 4 buttons
1 x LCD 1.44” SPI and ST7735 controller
1 x microSD/SDHC card module reader
1 x SDHC card
1 x speaker
1 X buzzer
1 X LED strip
1 X LED
3 X MOSFET N-MOS IRF540N transistor
1 X 220Ohm resistor
1 x XPT8871 mono audio amplifier
plenty of male-male and male-female wires

Circuit Layout

Circuit Design

Circuit Implementation

1. Arduino Uno (Rev3)

• Role: Central controller. Drives SPI for the display and SD, outputs PWM for audio/buzzer and scans the keypad.
• Power: Can use its onboard 5 V regulator (from VIN) or the two external AMS1117 regulators shown.

2. Voltage Regulators (U1 & U3)

• U1 (AMS1117-5 V):
  • Input: 7-12 V
  • Output: 5 V rail feeding:
    • Arduino 5 V pin
    • WS2812 LEDs
    • PAM8403 audio amp
    • Buzzer (through its series resistor)
• U3 (AMS1117-3.3 V)
  • Input: same VIN
  • Output: 3.3 V rail feeing:
    • TFT module
    • MicroSD module

3. TFT Display

• Power & Backlight
  • VCC → 3.3 V
  • GND → common ground
  • LED + (backlight) → 5 V
• SPI Signals (sharing the SPI bus)
  • SCK → D13 (hardware SCK)
  • MOSI → D11
  • CS → D10
  • DC → D9 (Data / Command select)
  • RST → D8

4. MicroSD Card Module

• Power
  • VCC → 3.3 V
  • GND → common ground
• SPI (same bus, separate CS)
  • MOSI → D11
  • MISO → D12
  • SCK → D13
  • CS → D4
• Separate CS allows the Arduino to select either the TFT or the SD card independently.

5. Audio Amplifier Module (PAM8403) + Speaker

• Power
  • VCC → 5 V
  • GND → common ground
• Inputs
  • L IN / R IN → PWM-filtered audio from Arduino
• Outputs
  • L OUT / R OUT → speaker
• Function: Boosts the Arduino's low-level PWM audio to drive a few-watt speaker.

6. Passive Buzzer

• Connections
  • One leg → D3 (PWM) through a 220 Ω resistor
  • Other leg → GND
• Function: Generates tones / alerts by toggling PWM at audio frequencies.

Real-life Circuit

06.05.2025 - decided on the project, wrote the description and the hardware materials
11.05.2025 - materials bought, starting on the hardware design
18.05.2025 - finished hardware design
19.05.2025 - uploaded circuit design and circuit layout

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