ATmega328p microcontroller board

ATmega328P Arduino Nano Clone — Custom MCU PCB Design

A fully custom Arduino Nano-compatible microcontroller board designed from scratch in KiCad. Implements the ATmega328P with USB-to-serial programming, onboard 5V/3.3V regulation, and a compact 2-layer layout — production-ready and Gerber-verified.

Overview

This project is a ground-up recreation of the Arduino Nano form factor using the ATmega328P microcontroller. Rather than using a pre-made module, the entire hardware stack was designed from scratch: oscillator circuit, decoupling strategy, USB-to-serial bridge for bootloader programming, voltage regulation, and pin breakout — all laid out in a compact 2-layer PCB.

This project demonstrates the ability to design real microcontroller hardware — the kind of work needed for custom embedded products where off-the-shelf dev boards aren't suitable.

Specifications

Design Highlights

Full ATmega328P Bring-Up Circuit

Includes all essential support circuitry: 16 MHz crystal with load capacitors, AVCC filtering with a ferrite bead and bulk capacitor, 100nF decoupling caps on all VCC/GND pins, and a proper reset circuit with pull-up resistor and filter capacitor.

USB-to-Serial Programming

The CH340G bridge handles USB communication and auto-reset for bootloader programming, matching the Arduino Nano behaviour exactly. DTR line connected through a 100nF capacitor to the MCU reset pin for reliable auto-reset during upload.

Onboard 3.3V Regulation

AMS1117-3.3 LDO provides a clean 3.3V rail for sensors and peripherals that require it, with input and output decoupling capacitors for stability.

Compact 2-Layer Layout

All components fit within a Nano-compatible footprint on a 2-layer board. Power and ground planes on bottom layer, signals routed cleanly on top. SMD components used throughout for compact placement.

DRC Passed

Full design rule check with zero errors. Trace widths verified for current capacity, clearances verified for standard PCB fab tolerances.

Repository Structure

project2-atmega328p-nano/
├── schematic/
│   └── atmega328p_nano.kicad_sch
├── pcb/
│   └── atmega328p_nano.kicad_pcb
├── gerbers/
│   ├── atmega328p_nano.GTL
│   ├── atmega328p_nano.GBL
│   ├── atmega328p_nano.GTO
│   ├── atmega328p_nano.GTS
│   ├── atmega328p_nano.GBS
│   └── atmega328p_nano.DRL
├── bom/
│   └── bom.csv
└── README.md

Bill of Materials (Key Components)

Schematic Sections

1. Power input & regulation — USB 5V in → AMS1117-3.3 → 3.3V rail
2. USB-to-Serial — CH340G with crystal, decoupling, and DTR auto-reset
3. ATmega328P core — MCU with crystal, decoupling, AVCC filter, reset
4. I/O breakout — all GPIO, analog, and power pins exposed on 2.54mm headers
5. ICSP header — for bootloader burning and direct ISP programming

Skills Demonstrated

• ATmega328P hardware bring-up and support circuit design
• USB-to-serial bridge integration (CH340G)
• LDO regulator selection and decoupling strategy
• SMD component placement and 2-layer PCB routing
• ICSP and bootloader programming interface design
• KiCad DRC and Gerber export

Project Status

About the Designer

Self-taught PCB designer specializing in KiCad — IoT, embedded systems, and industrial control boards. Available for freelance PCB design work: schematic capture, layout, DRC review, and Gerber preparation.

🔗 GitHub: [Abhi90808] 📧 [kvabhishek908@gmail.com]