KEYBOARD

Soup_pad – 104-Key Custom Mechanical Keyboard with Per-Key RGB
https://youtu.be/te1m4h9dRJE 

Project Overview
Soup_pad is a full-size 104-key custom mechanical keyboard built around the Raspberry Pi Pico. The goal of this project is to create a fully custom, manufacturable keyboard that balances cost, performance, and flexibility, while remaining accessible to hobbyists and students.

Unlike typical prebuilt keyboards, Soup_pad is designed from scratch — including PCB, firmware integration, and enclosure — making it a complete hardware development project rather than just an assembly.

Core Features

• Full 104-key layout (includes numpad and function row)
• Per-key RGB lighting using SK6812 Mini-E LEDs (individually addressable)
• USB interface via Raspberry Pi Pico
• Matrix-based key scanning (21 columns × 6 rows)
• Open firmware support (KMK / CircuitPython compatible)
• Cost-optimized design for practical manufacturing

Electronics & Schematic Design

The keyboard uses a matrix scanning architecture to efficiently read all key inputs using limited GPIO pins.

• Controller: Raspberry Pi Pico (RP2040 dual-core MCU)
• Matrix Design: 21×6 configuration using direct GPIO access
• RGB System: SK6812 Mini-E LEDs chained per key for dynamic lighting effects
• Power System:
  • Powered directly via USB (5V)
  • Decoupling capacitors placed near all major components
• Signal Considerations:
  • Clean routing for matrix lines to reduce interference
  • Proper grounding for stable LED operation

This design keeps the system simple and avoids unnecessary complexity while still supporting a large key matrix and RGB lighting.

Mechanical Design

• Compatible with Cherry MX-style switches
• Supports standard 104-key keycap sets
• Includes stabilizer mounts for larger keys
• Custom enclosure design provided as STEP files

The case is designed to be:

• Easy to manufacture (CNC / 3D print)
• Modular and repair-friendly
• Suitable for iterative prototyping

Innovative Aspects

While based on a standard microcontroller, the project introduces several practical innovations:

• Full-size keyboard driven directly by a compact microcontroller without expensive custom boards
• Per-key RGB in a cost-conscious design, avoiding premium components
• Open and modifiable platform for firmware experimentation (lighting effects, macros, layouts)
• Designed for learning and replication, not just end-use
• Complete hardware stack included (PCB + enclosure + firmware compatibility)

Project Purpose

Soup_pad is intended as a learning-oriented yet production-capable keyboard platform. It demonstrates how a widely available microcontroller like the Raspberry Pi Pico can be used to build a complex, real-world device.

This makes it valuable for:

• Students learning embedded systems and PCB design
• Hobbyists entering custom keyboard development
• Developers experimenting with firmware and RGB control

Files Provided

• PCB design files (Gerber + EasyEDA project)
• Schematic diagrams
• BOM (Bill of Materials)
• STEP files for enclosure
  
  

  The system is built around a 21×6 key matrix, allowing 104 keys to be scanned efficiently using limited GPIO pins.

  • Matrix Working Principle:
    Rows are driven sequentially while columns are read as inputs. This reduces required pins while maintaining responsiveness.
  • Microcontroller Role:
    The Raspberry Pi Pico handles:
    • Matrix scanning (input detection)
    • RGB data transmission (timing-critical SK6812 control)
    • USB communication with host system
  • RGB Circuit (SK6812 Mini-E):
    Each key has an individually addressable LED connected in a daisy chain.
    A single data line controls all LEDs, reducing wiring complexity while enabling advanced lighting effects.
  • Power Distribution:
    • USB provides 5V input
    • Capacitors are placed near LEDs and MCU for voltage stability
    • High-current paths for RGB are separated from logic where possible
  • Signal Integrity Considerations:
    • Short trace routing for matrix lines
    • Ground plane used to reduce noise
    • Stable data path for LED chain to prevent flickering

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  Project Functionality

  Soup_pad performs three core real-time operations:

  1. Key Detection
     Continuously scans the matrix to detect key presses with low latency.
  2. RGB Processing
     Drives per-key lighting effects such as:
     • Reactive typing effects
     • Layer-based lighting
     • Custom animations
  3. USB Communication
     Sends HID signals to the computer while simultaneously updating lighting states.

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  Innovative Features (Key Section)

  This project goes beyond a conventional keyboard in the following ways:

  • Dual-purpose Microcontroller Usage
    The Raspberry Pi Pico simultaneously handles real-time input scanning and strict-timing RGB control, which is typically separated in commercial designs.
  • Cost-Optimized Full-Size RGB Design
    Achieves per-key RGB on a 104-key layout without expensive driver ICs.
  • Firmware-Level Experimentation Platform
    Designed to support KMK, enabling:
    • Custom keymaps
    • Macros and layers
    • Programmable lighting behaviors
  • Hardware Designed for Modification
    The PCB and enclosure are built to allow:
    • Easy repair
    • Future feature additions (encoders, displays, etc.)