ATmega328 Minimal System V2.0

Overview

This is a minimal Arduino-compatible development board designed for the ATmega8/ATmega328 microcontroller family. The V2.0 variant features an extended 26-pin board adapter while maintaining identical functionality to the original design.

Key Features

Microcontroller Support

• ATmega8-16P or ATmega328P in DIP-28 package
• Arduino-compatible pinout and functionality
• 16MHz crystal oscillator for accurate timing

Power Management

• 1A Linear Voltage Regulator (5V output)
• Input voltage range: 7-35V DC
• Schottky Diode for USB/Board power separation (Rev 3 improvement)
• Power LED indicator

Connectivity & Interfaces

ISP Programming Header

• 6-pin ISP header for in-circuit programming
• Compatible with standard AVR programmers (USBasp, Arduino as ISP, etc.)
• Supports SPI communication through ISP pins

USB-to-Serial Interface

• 6-pin socket for FTDI USB-to-Serial converter
• Enables programming via bootloader
• Serial communication for debugging and data transfer

26-Pin Board Adapter (Main Feature)

All microcontroller signals are available on the extended connector:

• Digital I/O Pins: PB0-2, PC0-5, PD2-7
• ISP Signals: MISO, MOSI, SCK, RESET
• Serial Communication: RX, TX
• Power Rails: +5V, GND
• Additional Control Signals: Reset, etc.

Built-in Components

• Arduino-compatible LED on PB5 (Pin 13 equivalent)
• Reset circuitry with external reset button capability
• Crystal oscillator circuit (16MHz)
• Decoupling capacitors for stable operation

Board Specifications

• Dimensions: Compact form factor optimized for breadboard use
• Mounting: 4x mounting holes (2mm diameter)
• Pin Header Spacing: 30.73mm between pin headers
• PCB: Professional 2-layer design with silk screen

Revision History

• Rev 1: Initial design
• Rev 2: Fixed ISP header pin sequence (corrected footprint error)
• Rev 3: Added Schottky diode for USB/Board power isolation

Use Cases

This minimal system is ideal for:

• Prototyping Arduino-compatible projects
• Educational purposes for learning microcontroller programming
• Embedded system development with ATmega328P
• Custom PCB development using the 26-pin adapter interface
• IoT projects requiring minimal footprint
• Robotics applications with external sensor/actuator boards

Programming Options

1. ISP Programming: Using external programmer via 6-pin ISP header
2. Bootloader Programming: Via FTDI USB-to-Serial adapter (requires pre-installed bootloader)
3. Arduino as ISP: Using another Arduino board as programmer

Compatibility

• Fully compatible with Arduino IDE
• Supports Arduino libraries and sketches
• Compatible with ATmega8 and ATmega328P variants
• Works with standard Arduino shields (via 26-pin adapter)

Getting Started

1. Install ATmega328P microcontroller in DIP socket
2. Connect power supply (7-12V recommended) or USB via FTDI adapter
3. Connect programmer to ISP header or USB-Serial adapter
4. Upload your Arduino sketch
5. Connect external circuits via 26-pin adapter connector

This minimal system provides all essential features for ATmega328-based development while maintaining a compact and cost-effective design.