After all, the Arduino boards come with a host of benefits ... the Uno), fewer GND pins (two versus three), and no IOREF pin, which the Uno includes. You'll also notice that the Nano's pins ...

Most of us are familiar with the Arduino ... pin layout (Arduino shields likely won’t fit) and more I/Os than the ATmegas have. Sure, it’s not as practical as an actual Arduino Uno, but ...