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 Pro Trinket 3V or 5V but when size isn't as much of a concern and a USB-serial converter is required we reach for an Adafruit METRO.

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.

• ATmega328 brains - This popular chip has 32KB of flash (1/2 K is reserved for the bootloader) 2KB of RAM clocked at 16MHz
• 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 20 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.
• GPIO 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 avrdude and only uses 512 bytes.
• Beautiful styling by PaintYourDragon and Bruce Yan in Adafruit Black with gold plated pads.
• Works with all Adafruit designed shields!

This version of the METRO 328 comes as a fully assembled and tested development board but without any headers attached. We do include some through-hole headers that you can solder on if you like or you can solder wires or header directly to the breakout pads. We also include 4 rubber bumpers to keep it from slipping off your desk.

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