⚙️ Interfacing the Nextion HMI Display with ATmega328 Using Bare-Metal C

A clean and reliable approach to UART-based embedded HMI control

Building a responsive and user-friendly HMI for microcontroller-based systems is a key skill in embedded development. Recently, I completed a project where I successfully interfaced a Nextion HMI LCD display with the ATmega328P microcontroller — entirely using bare-metal C, without any Arduino libraries.

This implementation focuses on direct register-level programming, ensuring full control over UART communication and hardware behavior.

🔧 Project Overview

To test real-time control via an HMI, I created a simple UI in the Nextion Editor featuring two touch buttons:

🔘 Motor ON
🔘 Motor OFF

When a button is touched, the Nextion module transmits a specific serial command to the ATmega328. The microcontroller decodes this UART message, updates a text field on the HMI, and toggles a motor output connected to PB5.

✅ What This Project Demonstrates

This project helped validate several important embedded concepts:

🔹 Reliable UART Communication

The ATmega328P receives touch event data through UART at 9600 baud, confirming stable serial communication with the HMI.

🔹 Accurate Command Parsing

Each touch event sends a unique command. The firmware decodes these messages and triggers the appropriate action.

🔹 Real-Time Hardware Control

The motor output is updated instantly based on the user’s touch input, proving that the HMI can serve as a responsive control interface.

🛠️ Technical Specifications

Microcontroller: ATmega328P
Programming Method: Bare-metal C (register-level programming)
Interface: UART @ 9600 baud
HMI Module: 2.4” Nextion Display
Features Implemented:
- Touch-triggered motor control
- Serial command decoding
- On-screen text updates

🚀 Why This Matters

Interfacing a Nextion display without Arduino libraries provides:

A deeper understanding of UART communication
Full control over performance, memory usage, and interrupts
A scalable foundation for building advanced, professional embedded HMI systems

Even with just two buttons, this project demonstrates the power of combining graphical interfaces with low-level microcontroller control.

Small interface, big satisfaction — the MCU listens when you touch the screen! 😄

Here I’m sharing the Nextion HMI file, TFT file, and AVR project files for this project.
You can check them out here 👉 GitHub Repository: https://github.com/gsmanees/Embedded_Systems/tree/main/AVR/more/Touch_MotorControl

From touch to hardware action, this setup demonstrates the power of efficient UART-based embedded design.

Nextion HMI Interfaced with ATmega328 Using Bare-Metal C