STM32F446RET6 – Pinout Check (Register-Level)

A bare-metal GPIO pin verification project for the STM32F446RET6, written using direct register access — no STM32CubeMX, no HAL pin configuration, no abstraction layers.

This project is designed to validate MCU pin connectivity at the hardware level by configuring GPIO registers manually and toggling pins for physical verification (LED / multimeter / logic probe).

🎯 Project Objective

Before writing complex firmware, every embedded engineer must answer one simple question:

“Are my pins wired correctly?”

This repository solves exactly that problem using:

Direct register manipulation
Full control over GPIO configuration
Zero auto-generated code

Think of this as a power-on self-test for STM32F446RET6 pin integrity.

🧠 Why Register-Level Coding?

This project intentionally avoids CubeMX and HAL because:

✔️ You learn how the MCU actually works
✔️ No hidden code generation
✔️ No pin configuration magic
✔️ Perfect for debugging schematics and PCBs
✔️ Faster execution, zero overhead

If you understand this repo, you understand real embedded systems.

🧰 What This Project Does

Enables GPIO peripheral clocks using RCC
Configures GPIO pins via:
- MODER
- OTYPER
- OSPEEDR
- PUPDR
Toggles pins directly using:
- ODR (Output Data Register)
Helps visually confirm pin behavior using LEDs or probes

📁 Repository Structure

STM32F446RET6-Pinout-Check/
├── Core/
│   ├── Src/
│   │   └── main.c            # Register-level GPIO logic
│   ├── Inc/
│       └── main.h
├── Drivers/
│   └── CMSIS/                # Core & device headers
├── startup_stm32f446xx.s     # Startup file
├── STM32F446RETx_FLASH.ld    # Linker script
├── .cproject
├── .project
└── README.md

💡 No .ioc file is used for pin configuration
All pin settings are written manually in C.

🔌 Hardware Requirements

STM32F446RET6 (Nucleo or custom board)
LEDs + resistors or
Multimeter / logic analyzer
ST-LINK (onboard or external)

🚀 Getting Started

1️⃣ Clone the Repository

git clone https://github.com/DanielRajChristeen/STM32F446RET6-Pinout-Check.git

2️⃣ Open in STM32CubeIDE

File → Open Projects from File System
Select the cloned directory

3️⃣ Understand the Core Flow (main.c)

At a high level, the firmware does:

Enable GPIO clock
Set pin mode as output
Toggle pin state
Observe hardware response

Example (conceptual):

RCC->AHB1ENR |= RCC_AHB1ENR_GPIOAEN;
GPIOA->MODER |= (1U << (5 * 2));
GPIOA->ODR ^= (1U << 5);

This is raw MCU control — exactly how datasheets intend it.

4️⃣ Build & Flash

Click Build
Click Debug / Run
Observe LEDs or pin voltage changes

🧪 How to Use This for Pin Checking

Connect an LED (with resistor) to a target pin
Modify the pin number in code
Re-flash
Confirm LED toggles
Repeat for other pins

This process verifies:

GPIO routing
Board layout
MCU health
Schematic correctness

📘 Who Should Use This Repo?

🔰 Beginners learning STM32 internals
🧑‍💻 Embedded engineers debugging boards
🧠 Anyone transitioning from HAL → Register coding
🛠 Engineers validating new PCB designs

📈 Learning Outcomes

After working with this project, you will understand:

GPIO registers in STM32
Clock enabling via RCC
Bare-metal firmware flow
Startup + linker basics
Why abstraction layers exist (and when not to use them)

📝 License

This project is licensed under the MIT License.

MIT License

Copyright (c) 2025 Daniel Raj Christeen

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND.

Have a Great Developing Ahead!

DanielRajChristeen/STM32F446RET6-Pinout-Check