Blueprint PCB AW V3

Hackpad V1

This is my first real try for the Hack Club Blueprint challenge! I wanted to build something functional and learn the full process from PCB design to 3D modeling. This project was guided by the Hackpad Guide

1. The Idea

My goal was to create a clean and simple macro pad with the following features:

• 16 Mechanical Switches: A full 4x4 matrix for maximum input options.
• OLED Display: A 0.91" screen to show status or a clock.
• Rotary Encoder: An EC11 knob for volume control or scrolling.
• Simplicity: Keeping the design beginner-friendly but powerful.

Bill of Materials (BOM)

To build this, I am using the following components:

• 12x 1N4148 Diodes (Through-hole).
• 12x MX-Style Switches (Kailh Polia).
• 1x EC11 Rotary Encoder.
• 2x 100nF Ceramic Capacitors.
• 1x 0.91-inch OLED Display (SSD1306).
• 12x White Blank DSA Keycaps.
• 1x Seeed Studio XIAO RP2040 Controller.

Use Case

I will use it as a custom Small Numpad. The OLED screen will act as a system monitor or a simple clock to keep track of time while working or just to watch cool animations.

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2. Schematic & Electronics

I designed the circuit to be reliable and easy to solder. It uses a row-column matrix to handle all 16 switches with the limited pins of the XIAO.

Important to know The Rotary Encoder Switch just works to mute and unmute the Capacitor just there as backup! I would work without the Capacitors but for me its okay.

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3. PCB Design

This is the heart of the Hackpad. I routed everything carefully to fit the 4x4 grid and the extra components like the encoder and OLED.

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4. 3D Modeling & Case

This was my first time 3D modeling anything! I used Fusion 360 for the case design to ensure everything fits perfectly.

KiCad 3D Preview

First, I checked the component placement in KiCad's 3D viewer.

Fusion 360 Implementation

I exported the PCB as a .step file and imported it into Fusion 360 to build the case around it.

• PCB Size: 100mm x 100mm – a perfect size for a beginner like me.
• Case Interior: 100.5mm x 100.5mm to ensure a snug fit for the PCB.
• Case Exterior: 120mm x 120mm total width.
• Switch Cutouts: 14.2mm x 14.2mm for easy snapping of the MX switches.
• Dimensions: 12mm total height with a 3mm thick floor for stability.

Note: The top plate might need some light sanding for a perfect fit, but I can handle these tolerances during assembly!

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5. Firmware

The Crash Pad runs on KMK Firmware (CircuitPython).

• Layout: A standard Numpad layout (0–9, Backspace, Enter)
• OLED: Displays a custom logo and device name on a 128x32 SSD1306 display
• Encoder: Programmed as a System Mute toggle (works in all applications)

I am currently learning Python. This firmware was assisted by AI, but my own version is coming soon!