3.0 Specifications: ATMEGA328-Based Boards
The ATMEGA328 microcontroller is the foundation for some of the most popular and versatile boards in the Arduino ecosystem. This family is strategically important as it includes the flagship Arduino Uno, which serves as the platform’s reference design, as well as boards optimized for different form factors and power requirements. Specialized variants like the Arduino Pro Mini are designed for compact, embedded applications, while the LilyPad is tailored for wearable technology.
| Board Name | Operating Voltage | Clock Speed | Digital I/O Pins | Analog Inputs | PWM Outputs | UARTs | Programming Interface | |
| Arduino Uno R3 | 5V | 16MHz | 14 | 6 | 6 | 1 | USB via ATMega16U2 | |
| Arduino Uno R3 SMD | 5V | 16MHz | 14 | 6 | 6 | 1 | USB via ATMega16U2 | |
| Red Board | 5V | 16MHz | 14 | 6 | 6 | 1 | USB via FTDI | |
| Arduino Pro 3.3v/8 MHz | 3.3V | 8MHz | 14 | 6 | 6 | 1 | FTDI-Compatible Header | |
| Arduino Pro 5V/16MHz | 5V | 16MHz | 14 | 6 | 6 | 1 | FTDI-Compatible Header | |
| Arduino mini 05 | 5V | 16MHz | 14 | 8 | 6 | 1 | FTDI-Compatible Header | |
| Arduino Pro mini 3.3v/8mhz | 3.3V | 8MHz | 14 | 8 | 6 | 1 | FTDI-Compatible Header | |
| Arduino Pro mini 5v/16mhz | 5V | 16MHz | 14 | 8 | 6 | 1 | FTDI-Compatible Header | |
| Arduino Ethernet | 5V | 16MHz | 14 | 6 | 6 | 1 | FTDI-Compatible Header | |
| Arduino Fio | 3.3V | 8MHz | 14 | 8 | 6 | 1 | FTDI-Compatible Header | |
| LilyPad Arduino 328 main board | 3.3V | 8MHz | 14 | 6 | 6 | 1 | FTDI-Compatible Header | |
| LilyPad Arduino simple board | 3.3V | 8MHz | 9 | 4 | 5 | 0 | FTDI-Compatible Header |
Next, this specification will cover boards built around the ATMEGA32u4 microcontroller, which offers unique USB capabilities.