Simple table tennis scoreboard operated with buttons mounted under the table. Indicates whose serve it is, plays a jingle when the game is over.

My fiancée and I got a table tennis table, and quickly found we are (read: I am) terrible at keeping score in our heads. I figured it would be a fun project to design a scoreboard.

When I made this, I felt quite well-versed in everything needed to build it, so it was a relaxing project to work on. The only thing particularly new to me was driving a piezo speaker. The speaker was a pretty late addition, added only because there was some left-over program memory on the microcontroller, and I felt a happy jingle would really rub it in for the loser. ;-)

Features

• Arcade-style buttons mounted under the table on each side, pressed to give add a point to that side
• 4-digit 7-segment display indicating score in the current game
• Button to toggle display between current game score, number of games won since powerup, and total number of games won (stored in EEPROM)
• Reset function to clear games won since powerup, or all time
• LEDs indicating whose turn it is to serve
• “Undo” function by pressing and holding a player’s button, if the player mistakenly gave themself a point
• “Swap sides” function by pressing and holding both player buttons (swaps scores in all 3 counters)
• Audio feedback for button press, long press
• Game over jingle when a player wins the game
• 11 Point game with 2 points difference win condition (or however many points it takes to get 2 points difference beyond 11)
• Powered via micro-usb connection

The device is built around the lightweight Microchip ATTiny84 microcontroller and Maxim Integrated MAX7219 display driver, which also drives 5 indication LEDs. I managed to fill up virtually all of the program memory; I had to optimize the code a bit to make it all fit after adding the audio portion of the firmware.

Work Involved

• Circuit design / breadboarding prototype
• Firmware development (plain AVR-C, built with a Makefile, avr-gcc, flashed with AVRDUDE)
• Schematic capture (KiCad)
• PCB design (KiCad)
• PCB assembly (through-hole soldering)
• 3D-printable case design (FreeCAD)
• 3D-Printable button case design (FreeCAD)
• Wiring and assembly of button units

Additional Images

The breadboarded prototype, simple enough to fit on a small breadboard:

The finished PCB, powered up:

Board, and buttons in their 3D printed cases:

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Circuit/PCB designs and firmware code can be found on GitHub: pingpong-scoreboard