Custom Mechanical MacroPad

A fully programmable, custom-built mechanical shortcut keypad (MacroPad) designed to streamline workflows, trigger complex macros, and automate repetitive desktop tasks. This project integrates custom mechanical design (CAD), hardware prototyping, and low-latency embedded C++ firmware.

🚀 Key Features

• Programmable Key Matrix: Utilizes an efficient matrix wiring design to maximize input counts while optimizing microcontroller GPIO pin usage.
• Low-Latency HID Interaction: Configured as a native USB HID (Human Interface Device), sending high-speed keystrokes, shortcuts, and complex multi-key macro strings instantly.
• Layer-Based Profiles: Supports multi-layer mapping (e.g., Layer 0 for media/OS navigation, Layer 1 for CAD/Development hotkeys) toggled seamlessly via modifier keys.

Electronics & Matrix Wiring

To keep the footprint minimal and the controller cost-effective, the key layout uses a matrix scanning technique using diodes to prevent ghosting (where pressing multiple keys simultaneously registers unintended inputs).

Component	Technical Specification
Microcontroller	High-speed, USB-native board (e.g., Arduino Pro Micro / RP2040)
Switches	Mechanical linear/tactile switches with 19mm standard spacing
Diodes	1N4148 fast-switching signal diodes for anti-ghosting matrix circuitry
Interface	Wired USB-C/Micro-USB interface with native hardware support

💻 Firmware Architecture

The application layer is built in modern embedded C++ and revolves around a non-blocking debounce and scan loop to capture inputs at the millisecond scale.

Key Matrix Scanning Logic:

1. Row Strobe: Pulls a single row pin LOW or HIGH.
2. Column Read: Checks all column pins to see if any circuit is completed by a key press.
3. Debounce Filter: Implements a software-based interval filter (typically 5ms) to ignore the electrical noise caused by physical switch contacts bouncing upon impact.
4. HID Transmission: Transmits the corresponding keycode array via the USB interface.

       Column 0      Column 1
          │             │
Row 0 ────┼───[Key]─────┼───[Key]
          │   └───┤►├───┘   └───┤►├───
          │             │
Row 1 ────┼───[Key]─────┼───[Key]
          │   └───┤►├───┘   └───┤►├───