Digital Scoreboard: ESP32 + E-ink

I built this scoreboard to replace the paper scorecards and whiteboards we used for PE and school sport. It shows the score and whose serve it is, and nothing else, in large seven-segment digits you can read from the sideline. Scoring uses five clicky mechanical switches, so a press is deliberate and you don't get accidental double points mid-rally.

I tested the finished build at a badminton tournament with real players, referees and spectators. Their feedback led to two changes in this version:

• The serve indicator now takes up the whole bottom line of the display, because people couldn't tell which side was serving from a distance.

• Every keycap now has an indented icon. Most first-time users had to ask what each button did. The icons can be felt as well as seen, so a scorer can find the right button without looking away from the court.

Features

• Large seven-segment digits drawn in code, so they stay sharp at any size

• Black-and-white display with a switchable background (white on black or black on white) for different lighting

• Serve indicator across the full bottom of the screen

• Five mechanical switches in recessed wells, each with an indented icon

• Undo and reset buttons, so a wrong press is easy to fix

• Rechargeable 10000mAh battery. E-ink only uses power when it refreshes, so it lasts a long time.

• USB-C charging from the back without opening the case

• Wi-Fi support through the ESP32, with an external antenna

• Fully repairable. The front, top and back panels all bolt into heat-set inserts, and the battery sits in a two-part clamp so it can be replaced.

• Printed in grey so it can be painted in your school or club colours

Controls

• Outer two buttons (+): add a point for each side

• Middle button: reset

• Mid-left button: serve toggle

• Mid-right button (−): undo

Printed parts

• Main body

• Front plate

• Top plate

• Back panel

• Battery clamp (two halves)

• Keycaps (large and small)

Hardware you'll need

• ESP32 development board with an external antenna

• Tri-colour (red/black/white) e-ink display with driver board, 170.2 × 111.2 mm panel outline. It runs in black and white mode.

• 5 × Kailh Box White mechanical switches

• Custom switch PCB. The KiCad files and Gerbers are on GitHub. Mine was made by JLCPCB.

• 10000mAh rechargeable battery with a power switch

• USB-C panel-mount extension (carries power only)

• M2 and M4 heat-set inserts, with matching screws

• M4 bolts to mount the PCB

• Jumper wires

• Hot glue

Assembly

1. Print all parts flat. None of them need supports.

2. Press the heat-set inserts into their holes. Tighten screws firmly but don't crank them, because overtightening pulls the inserts out of the PLA.

3. Tape the switches onto the PCB before soldering so they sit square, then solder them. Check each trace and switch with a multimeter continuity test first.

4. Fit the display into the front notch. Mount the ESP32 with two screws and connect the display ribbon cable. The fit is tight, so take your time.

5. Bolt the PCB to the top plate with M4 bolts. Wire each switch to its GPIO pin using the pin map on GitHub, then hot glue the jumper wires so they don't shake loose.

6. Put the battery into the two-part clamp.

7. Assemble in this order: main body, front plate, top plate, then the back panel last. The USB-C extension mounts on the back panel.

8. Turn the battery switch on before closing the back panel.

9. Push the keycaps onto the switches.

Code
The code, pin map and PCB files are on GitHub: https://github.com/SugerStudio/DigiScoreboard-code

To build it, you need:

• the Arduino IDE

• the ESP32 board package

• the GxEPD2 library (3-colour driver)

• the Adafruit GFX library

Known limitations

• A full e-ink refresh takes around 2.5 to 3 seconds and flashes the whole screen. You'll notice it between points.

• Only one button press registers at a time, so there are no two-button combos.

• The USB-C port only carries power. To upload new code, remove the back panel and plug straight into the ESP32. This also means nobody can change the code mid-match.

• The scoreboard doesn't have a mount or stand yet.

Credits

• Switch footprints: ScottoKeebs by Joe Scotto (CC BY-NC-SA 4.0)

• Display library: GxEPD2 by Jean-Marc Zingg (GPL-3.0)

• Adafruit GFX Library by Adafruit

• Arduino core for the ESP32 by Espressif