🔢 STM32 7-Segment Display Interface (Register Coding Method)

This repository demonstrates how to interface a 7-segment display with the STM32F446RET6 microcontroller using pure register-level programming (no HAL, no CubeMX logic).

The project is aimed at embedded beginners who want to understand what actually happens at the register level when driving a display.

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📌 Project Overview

• Controller: STM32F446RET6 (NUCLEO Board)

• Display: Single-digit 7-Segment (Common Cathode)

• Coding Style: Direct Register Programming

• IDE: STM32CubeIDE

• Logic Demonstrated:

  • Display numbers 0 → 9
  • Reverse count 8 → 1
  • Continuous loop operation

This project focuses on GPIO register control without any abstraction layers.

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🧠 Why Register Coding?

HAL is powerful, but register coding helps you:

• Understand STM32 hardware internals
• Gain fine-grained control over peripherals
• Improve debugging confidence
• Prepare for interviews and low-level roles
• Write efficient and deterministic code

This repo intentionally avoids HAL APIs to keep learning transparent.

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🔌 Hardware Connections

7-Segment (Common Cathode) → STM32F446RET6

Segment	STM32 Pin
a	D7
b	D8
c	D9
d	D10
e	D11
f	D12
g	D13

⚠️ Use current-limiting resistors (220Ω – 330Ω) for each segment.

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🔧 Pin Configuration (Register Level)

• GPIO Port: GPIOA / GPIOB (based on board mapping)
• Mode: General Purpose Output
• Output Type: Push-Pull
• Speed: Low / Medium
• Pull-up/Pull-down: None

Configured manually using:

• RCC->AHB1ENR
• GPIOx->MODER
• GPIOx->ODR

No .ioc pin logic is used.

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🧮 Display Logic

Each digit is represented by a bit pattern for segments a–g.

Example:

// Digit 0 (a b c d e f ON, g OFF)
0b0111111

The code:

1. Clears GPIO output
2. Sets required segment bits
3. Applies delay
4. Moves to next digit

Reverse counting uses the same logic in opposite order.

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⏱ Delay Implementation

• Software delay using a simple loop
• No SysTick or timer abstraction
• Helps beginners visualize execution timing

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📂 Project Structure

STM32-7-Segment-Interface-Display-Register-Coding-Method
├── Core
│   ├── Src
│   │   └── main.c        // Complete register-level logic
│   └── Inc
├── Drivers
├── STM32CubeIDE files
└── README.md

Focus file: Core/Src/main.c

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▶️ How to Run

1. Clone the repository:

git clone https://github.com/DanielRajChristeen/STM32-7-Segment-Interface-Display-Register-Coding-Method.git

2. Open using STM32CubeIDE
3. Build the project
4. Flash to NUCLEO-F446RE
5. Observe the 7-segment counting sequence

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🧪 Learning Outcomes

After completing this project, you will understand:

• GPIO clock enabling using RCC
• GPIO mode configuration via registers
• Output Data Register (ODR) manipulation
• Binary mapping of display segments
• Difference between HAL vs Register coding
• Practical embedded debugging mindset

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🧩 Extensions You Can Try

• Add decimal point (DP)
• Use Common Anode display
• Convert logic to HAL method
• Replace delay loop with SysTick
• Extend to multi-digit multiplexing

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📜 License

This project is licensed under the MIT License. Feel free to use, modify, and share for learning and teaching.

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🤝 Contribution & Feedback

This repo is built for learning-by-doing. Suggestions, issues, and improvements are always welcome.

If this helped you, ⭐ star the repo and keep learning embedded systems the right way.

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