Adafruit METRO 328 with Headers - ATmega328

Adafruit sure loves the ATmega328, they use them a lot for their 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 they need to go small, they use a Pro Trinket 3V or 5V, but when size isn't as much of a concern, and an USB-serial converter is required, we reach for an Adafruit METRO. This is the Adafruit METRO with headers.  It comes with headers soldered on.  It's a fully assembled and tested board with SMT headers attached as well as through hole headers.  If you don't want a Metro with through-hole headers or at least, holes for them, but not attached for super-slimness, check out their Metro without Headers. METRO is the culmination of years of playing with AVRs: Adafruit 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 Power the METRO with 7-9V polarity protect