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We sure love the ATmega328 here at Adafruit, and we use them a lot for our own projects. The processor has plenty of GPIO, Analog inputs, hardware UA...

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We sure love the ATmega328 here at Adafruit, and we use them a lot for our own projects. The processor has plenty of GPIO, Analog inputs, hardware UART SPI and I2C, timers and PWM galore - just enough for most simple projects. When we need to go small, we use a Metro Mini or a Trinket M0, but when size isn't as much of a concern, we reach for an Adafruit METRO.

New! We've updated this product to our Adafruit Metro 328, a fully assembled Arduino-compatible. If using with the Arduino IDE, select "Arduino UNO" in the board selection drop down.

This is the Adafruit METRO with headers.  It comes with headers soldered on.  It's a fully assembled and tested board with through-hole headers attached.  If you don't want a Metro with the headers attached for super-slimness, check out our Metro without Headers.

METRO is the culmination of years of playing with AVRs: we wanted to make a development board that is easy to use and is hacker friendly. At the heart is an ATmega328P, with 32KB of flash and 2KB of RAM, running at 16 MHz. It comes with the Optiboot bootloader already installed, and is Arduino IDE compatible.

  • Power the METRO with 7-9V polarity protected DC or the micro USB connector to any 5V USB source. The 2.1mm DC jack has an on/off switch next to it so you can turn off your setup easily. The METRO will automagically switch between USB and DC.
  • METRO has 19 GPIO pins, 6 of which are Analog in as well, and 2 of which are reserved for the USB-serial converter. There's also 6 PWMs available on 3 timers (1 x 16-bit, 2 x 8-bit). There's a hardware SPI port, hardware I2C port and hardware UART to USB. Logic level is 5V but by cutting and soldering closed a jumper, you can easily convert it to 3.3V logic
  • USB to Serial converter, there's a hardware USB to Serial converter that can be used by any computer to listen/send data to the METRO, and can also be used to launch and update code via the bootloader
  • Four indicator LEDs, on the front edge of the PCB, for easy debugging. One green power LED, two RX/TX LEDs for the UART, and a red LED connected to pin PB5
  • Easy reprogramming, comes pre-loaded with the Optiboot bootloader, which is supported by Arduino IDE, and avrdude and only uses 512 bytes - so you have lots of space for your code!
  • Arduino IDE compatible, you can use this with the Arduino IDE (both desktop and cloud version) by selecting 'Arduino UNO' in the Boards menu.
  • Works with all Adafruit shields!

We also include 4 rubber bumpers to keep it from slipping off your desk. Metro shown with our 12x capacitive touch shield attached just to demonstrate the headers, but that shield is not included!

Mac & Windows People! Don't forget to grab & install the CP2014 VCP drivers from SiLabs to make the COM/Serial port show up right! The default drivers may not support this USB/Serial chip


Jargon buster

Plain-language definitions for the technical terms used above.

ATmega328P
An 8-bit microcontroller chip used on many Arduino Uno-compatible boards. Knowing the controller uses an ATmega328P helps you understand its memory, speed, pin compatibility, and the Arduino sketches it can run.
Bootloader
Small starter software on a microcontroller that lets new code be uploaded before the main program runs. Knowing how to enter bootloader mode matters when you need to program the board or recover it after a faulty sketch.
GPIO
General-purpose input/output pins are microcontroller pins you can set in software to read signals, switch devices on and off, or connect to peripherals. The number of GPIO pins matters because it limits how many buttons, LEDs, sensors, and other parts you can wire directly to the board.
Headers
Rows of metal pins used to plug a module into a breadboard or connect it with jumper wires. Pre-soldered headers make the module easier to use straight away without needing to solder the pins yourself.
I2C
I2C is a two-wire communication bus used by many sensors and small modules. It matters because several I2C devices can share the same two wires, but each device needs a compatible address and your controller must support I2C.
IDE
Short for Integrated Development Environment, a program used to write, run and manage code. It matters because some learners prefer a traditional coding workspace instead of a guided notebook-style lesson.
LED
A light-emitting diode is a small electronic component that lights up when current flows through it in the correct direction. In this kit, LEDs create the flashing effect, so polarity and correct soldering matter for the project to work.
PCB
A printed circuit board is a rigid board with copper tracks that connect electronic parts without loose wires. For this kit, the PCBs also form the airplane shape, so they are both the circuit base and part of the finished model.
PWM
Pulse Width Modulation is a way for a digital pin to simulate variable output power by switching on and off very quickly. It matters for controlling things like LED brightness, motor speed, or servo-style signals from a microcontroller pin.
RAM
RAM is temporary memory used while a device is running, and its contents are lost when power is removed. A “Run in RAM” mode is useful for testing settings without permanently programming the module, but it may not support every feature.
SPI
A fast serial communication bus often used for displays, memory cards, and sensors. It matters because SPI devices need specific pins for clock and data, plus a separate chip-select line for each device.
UART
UART is a simple serial connection that sends data over separate transmit and receive wires, often labelled TX and RX. It matters because this module is designed to replace a wired UART cable with a wireless link while keeping the same serial data format.
USB to serial converter
A chip that turns the USB connection from your computer into serial data that the microcontroller can understand. It matters because this board uses it for programming and debugging instead of appearing as a direct native USB device such as a keyboard or mouse.
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