Adafruit METRO 328 with Headers [ATmega328]

The Adafruit METRO 328 is a fully assembled, Arduino UNO R3-compatible development board powered by the ATmega328P running at 16 MHz. It's shape and pin-compatible with Arduino UNO R3 shields, and works directly with the Arduino IDE by selecting "Arduino UNO" in the Boards menu. This version comes with through-hole headers pre-soldered — for a slimmer profile, see the METRO 328 without Headers.

The METRO is the result of years of AVR development experience, designed to be both easy to use and hacker-friendly. It features an on-board USB-to-serial converter, polarity-protected DC jack with power switch, and comes pre-loaded with the Optiboot bootloader.

Key Features

• ATmega328P @ 16 MHz – 32 KB flash, 2 KB RAM with Optiboot bootloader pre-installed
• Arduino UNO R3 Compatible – Works with UNO shields and the Arduino IDE (desktop and cloud)
• 19 GPIO Pins – Including 6 analogue inputs and 6 PWM outputs across 3 timers
• Hardware SPI, I2C & UART – Full serial communication support
• USB-to-Serial Converter – On-board CP2104 for programming and serial monitoring
• Flexible Power – USB or 7–9V DC with polarity protection and auto-switching
• On/Off Switch – Conveniently located next to the DC jack
• 5V Logic (3.3V Optional) – Cut and solder a jumper to switch to 3.3V logic
• Four Indicator LEDs – Power (green), RX/TX (yellow), and pin 13 (red)

Ideal For

• Arduino projects requiring UNO R3 shield compatibility
• Beginners learning microcontroller programming
• Prototyping with the Arduino ecosystem
• Projects needing a reliable, well-documented ATmega328P platform

Package Contents

• 1× Adafruit METRO 328 board (with headers pre-soldered)
• 4× Rubber bumper feet

Resources

• Optiboot Bootloader (GitHub)