Adafruit metro mini 328 5v 16mhz with ftdi usb to serial adafruit 2590 p the adafruit metro mini 328 is what you get when you take an arduino uno and build it using some of the smallest components available measuring only 18 x 44mm and a super slim 4mm high the metro mini packs in all the functionality of the full size arduino based around the atmega328 it has 32kbytes of flash 2kbytes of ram and runs at 16mhz it has 18 gpios including 6 x pwm and 6 x analogue in plus hardware suppo