Press Counter with LED Codes (STM32 NUCLEO-F446RE)

A bare-metal STM32 firmware project that counts button presses and displays the count using LED blink codes.

This project is implemented using direct register manipulation without HAL libraries.

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Project Overview

The firmware has two operating phases.

Phase 1 — Counting

• Press the onboard button between 1 and 9 times.
• Every valid press produces a short LED flash.
• If no button is pressed for approximately two seconds, the firmware switches to display mode.

Phase 2 — Display

The LED blinks back the number of recorded button presses.

Example

If the button was pressed four times:

Blink

Blink

Blink

Blink

Pause

Repeat

During display mode, pressing the button resets the counter and returns the firmware to counting mode.

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Hardware

• STM32 NUCLEO-F446RE
• USB Cable

No external hardware is required.

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Pin Mapping

Function	Pin
LED	PA5
Button	PC13

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Concepts Demonstrated

• Register-level GPIO programming
• Memory-mapped I/O
• RCC clock enabling
• Active LOW button logic
• Polling
• Software debouncing
• Edge detection
• Timeout detection
• Counter variables
• Two-phase state machine
• LED data encoding

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Software Architecture

COUNTING
    |
    | 2 seconds without button press
    V
DISPLAYING
    |
    | Button Press
    V
COUNTING

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Build Instructions

1. Open STM32CubeIDE
2. Create a project for the NUCLEO-F446RE
3. Replace Core/Src/main.c
4. Build
5. Flash
6. Run

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Folder Structure

stm32-press-counter-led-codes
│
├── README.md
├── .gitignore
├── docs
│   └── wiring.md
└── src
    └── main.c

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Future Improvements

• Timer interrupts
• UART output
• Seven-segment display
• LCD interface
• Persistent storage