Raspberry Pi Pico W Keypad-to-LED Controller

A Raspberry Pi Pico W (RP2040) firmware project that reads a 4x4 matrix keypad and controls 12 LEDs using Arduino-style C++ logic.

Scope of this repository refresh: Documentation and project organization were improved while preserving the original runtime behavior in src/main.cpp.

Repository Structure

.
├── CMakeLists.txt
├── diagram.json
├── include/
│   └── .gitkeep
├── src/
│   └── main.cpp
└── docs/
    ├── architecture.md
    └── wiring.md

Project Features

• 4x4 matrix keypad input via Keypad library.
• 12 independent LED outputs.
• Group actions:
  • 9: turn ON LEDs 1..8
  • 0: turn OFF LEDs 1..8
  • *: turn ON LEDs A..D
  • #: turn OFF LEDs A..D
• Direct actions:
  • 1..8: turn ON individual blue LEDs
  • A..D: turn ON individual red LEDs

Components List (derived from diagram.json + source mapping)

• 1x Raspberry Pi Pico / Pico W-compatible RP2040 board footprint
• 1x 4x4 membrane keypad
• 12x LEDs (8 blue, 4 red)
• 12x 220Ω resistors (LED current limiting)
• 4x 1kΩ resistors (keypad row pull-up network)
• Jumper wires and USB power/programming cable

GPIO Pin Summary

• Keypad columns: GP16, GP17, GP18, GP19
• Keypad rows: GP26, GP22, GP21, GP20
• LED outputs: GP11, GP10, GP9, GP8, GP7, GP6, GP5, GP4, GP3, GP2, GP28, GP27

For the full table and physical signal mapping, see docs/wiring.md.

How to Run in Wokwi

1. Create/open a Raspberry Pi Pico project in Wokwi.
2. Replace Wokwi diagram.json with this repo's diagram.json.
3. Replace the sketch source with src/main.cpp.
4. Add/install library Keypad in Wokwi's library manager.
5. Start simulation and press keypad keys to verify LED behavior.

How to Run on Real Hardware (Pico W)

Arduino IDE path (recommended for this source as-is)

1. Install Arduino IDE 2.x.
2. Install the RP2040 board package (Earle Philhower core).
3. Install library: Keypad (Mark Stanley / Alexander Brevig).
4. Open/use src/main.cpp as your sketch content.
5. Select board: Raspberry Pi Pico W.
6. Enter BOOTSEL mode if needed and upload.

Pico SDK path (note)

This code is Arduino-API-based (setup, loop, digitalWrite, Keypad.h). If you use pure Pico SDK, preserve logic and add a thin adaptation layer.

Wi-Fi & Secrets

• Pico W Wi-Fi hardware is not used in this firmware.
• No SSID/password or cloud credentials are required.
• Do not hardcode credentials if you later extend this project with networking.

Behavior Preservation Statement

src/main.cpp intentionally retains the provided control logic without behavioral changes.