THE PROJECT: Custom-designed mechanical Macro Pad or 4x4 Matrix Numpad

ARCHITECTURE: This hardware module is an advanced 16-key matrix input peripheral designed for microcontrollers (e.g., Arduino, ESP32) or USB HID controllers (e.g., RP2040, ATmega32U4). Unlike low-cost consumer keypads, this architecture implements per-key diode isolation. This layout completely eliminates ghosting and masking, enabling true N-Key Rollover (NKRO) for high-performance applications like macro pads, gaming inputs, and secure entry systems

HARDWARE DESCRIPTION:

1. Cherry MX-style switches -> not simple SW_Push switches -> adds comfortability, rigidity, finishing look

used 5-pin PCB-mount switches instead of 3-pin variations -> adds stablisation

1. Diode -> to prevent ghosting effect when more that one key is pressed at a time
2. 1x8 pin header footprint at a standard 2.54mm pitch -> easy to plub it in the breadboard or connect it to any microcontroller directly with male to female jumber wires

PINOUT DEFENITION:

MATRIX SCAN:

The Ghosting Problem (Standard Keypads)

In a basic matrix, pressing three corners of a square (e.g., SW1, SW2, and SW5) creates an unintended current path back through the unpressed fourth switch (SW6). This tricks the microcontroller into registering a "ghost" press.

The Diode Solution (This Design)

Your custom PCB places a steering diode in series with every single mechanical switch.

Current can only flow from Row to Column (Row-to-Column configuration).

If multiple keys are struck simultaneously, reverse voltage spikes are fully blocked by the diodes.

This isolates every switch, allowing the MCU to accurately map any combination of concurrent inputs.

WHY I BUILT THIS?

This is a trail version of my c type usb + BLE numpad for my laptop without numpad

Also, i have interest in designing gamepad, numpad, custom keyboard and mouse