2 layers223.5 × 160 mm
2 layers14 × 26.7 mm
Modular Synths for Everyone
- Size
- 14 × 26.7 mm
- Copper layers
- 2
- Thickness
- 1.6 mm
- Parts
- 3
- Nets
- 20
- Pads
- 45
- Tracks, vias
- 115, 12
- Routed
- Yes
- KiCad
- KiCad 8.0 (file 20240108)
- Created
- 4 Oct 2024
- Updated
- 25 Oct 2026
Overview
MCUs is an open-source printed circuit board by bread-modular, from the bread-modular/bread-modular repository on GitHub, published under the MIT licence. It is a 2-layer board of 14 × 26.7 mm with 3 parts on 20 nets, routed with 115 tracks and 12 vias.
It is built around the ATTINY1616-MN. Its parts include 2 connectors and 1 IC. It belongs with the audio and music boards and the AVR (ATmega, ATtiny) boards of this library.
Main components
1README
README.mdBread Modular
An open-source hardware modular synthesizer format designed to be minimalistic and cost-effective: USB-powered, breadboard-friendly, with analog/digital modules and MIDI alongside CV & Gate.
Find your starting point
- Build or explore: modules, specification, common parts.
- Set up KiCad libraries: workspace/library setup. Projects
use the shared
opt/fp-lib-table; initialization copies local submodules rather than cloning them. - Check/export/source parts: KiCad toolkit.
Canonical tools, JLCPCB utilities and skills live under
opt/kicad-tools/.
KiCad quick start
python3 -B opt/kicad-tools/kicad_tools.py --help
python3 -B opt/kicad-tools/kicad_tools.py doctor
python3 -B opt/kicad-tools/kicad_tools.py export --helpPython + installed KiCad CLI; no extra packages for core tools. Private checks,
Gerber/BOM/CPL export, native netlist helpers and read-only sourcing have
distinct requirements and safety boundaries.
Exports are not electrical/release/order approval; keep frozen module scripts
and production designs untouched. Historical opt/kicad-jlcpcb and
.agents/skills/{kicad-workflow,jlcpcb-assembly} resolve through
relative compatibility symlinks.
Agents: start with the KiCad workflow skill or assembly skill, then actual CLI help.
Project references
Module catalog · Modular MIDI · PCB assembly
- Standalone exporter / native part-number setup
- Sourcing, audits and passive planning
- 32bit-5v sourcing / release HOLD
- 16bit-5v sourcing HOLD evidence
Project image and full feature overview
- Modular design: Just like Eurorack.
- USB-powered: It can be portable.
- Minimal design: Cost-effective.
- Modular MIDI support: Communicate between modules; CV & Gate still supported.
- Analog and digital signal paths: It’s your choice.
- Diverse built-in modules: A wide range of pre-designed modules.
- Configurable digital modules: Voice and CV using AtTiny 1616 or ESP32.
- Fully open source: Schematics, PCB designs and code.
- Ease of customization: Create modules tailored to your needs.
- No case required: Use directly on a breadboard or a simple base module.
Parts
3| Qty | Value | Footprint | References |
|---|---|---|---|
| 1 | ATtiny1616-M | Package_DFN_QFN:VQFN-20-1EP_3x3mm_P0.4mm_EP1.7x1.7mm | U1 |
| 1 | LEFT | Connector_PinSocket_2.54mm:PinSocket_1x10_P2.54mm_Vertical | J1 |
| 1 | RIGHT | Connector_PinSocket_2.54mm:PinSocket_1x10_P2.54mm_Vertical | J2 |
Questions
How big is the MCUs PCB?
It measures 14 × 26.7 mm and has 2 copper layers, 1.6 mm thick.
What parts does the MCUs use?
3 parts, built around the ATTINY1616-MN. The full list of its parts is on this page, with links to each part's symbol and footprint where PCBKit's library has them.
Where can I download the MCUs KiCad files?
From the bread-modular/bread-modular repository on GitHub, at the commit this page was made from: the board is opt/Breakouts/Attiny1616/MCUs.kicad_pcb. PCBKit opens the board in the browser, with nothing to install.
Can I use the MCUs design in my own project?
Its repository publishes it under the MIT licence: you may reuse it on that licence's terms (keep the author's notice, and for a copyleft licence share your changes alike).
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