ArcDice

ArcDice is a compact ATtiny13-based digital dice project with a 7-LED face, low-power sleep behavior, and a matching KiCad hardware design.

Keywords: digital dice, ATtiny13 dice, LED dice, DIY electronic dice.

What It Does

• Rolls a random value from 1 to 6 with a short LED animation.
• Drives a 7-point dice face from only 4 MCU output lines.
• Uses button wake-up and sleep mode to reduce power draw.

Firmware

• Source: src/main.cpp
• PlatformIO environment: attiny13a
• Upload protocol: usbasp

Pin Mapping

• PB0 -> center LED segment
• PB1 -> diagonal A (top-left + bottom-right)
• PB2 -> diagonal B (top-right + bottom-left)
• PB3 -> middle row (left-middle + right-middle)
• PB4 -> roll button (to GND, internal pull-up)

Dice Face Layout

The 7 visible pips are arranged on a 3x3 grid and lit via 4 logical groups (center, two diagonals, middle row). The resulting faces are:

Roll	Pattern	Description
1	center	single center pip
2	diagonal A	two corner pips (TL+BR)
3	center + diagonal A	vertical middle column (TL + center + BR)
4	diagonal A + diagonal B	four corners (full X)
5	center + both diagonals	full X plus center
6	both diagonals + middle row	four corners + middle two

Note: face 3 uses diagonal A (TL+BR) plus center, giving a symmetric vertical middle column -- the standard 7-pip rendering of 3.

Hardware

• KiCad project files:
  • hardware/ArcDice.kicad_pro
  • hardware/ArcDice.kicad_sch
  • hardware/ArcDice.kicad_pcb
• Power target: 1S Li-ion/LiPo with TP4056 protected module
• Recommended LED resistors: 220 ohm (one per LED)

Images

Assembled Board

Bare PCB

3D Top

3D Bottom

Schematic v1

Build And Upload

1. Install PlatformIO.
2. Connect an ATtiny13 programmer (USBasp).
3. Build and upload:

pio run -e attiny13a -t upload

Additional Documentation

• CHANGELOG.md — release history and notable changes.
• docs/BOM.md — bill of materials with footprints and suggested supplier parts.

License

MIT. See LICENSE.