Input and Output Each of the 14 digital pins on the Arduino Uno can be used as an input or output, using pinMode (), digitalWrite (), and digitalRead () functions. They operate at 5 volts. Each pin ...

The Arduino Nano and Uno are equipped with very similar processors (the chip that essentially serves as the brain of the board). The Nano features an ATmega328, while the Uno sports an ATmega328P.

Keeping the pinout, voltage and form factor unchanged from the UNO R3 ensures maximum hardware and electrical compatibility with existing shields and projects while allowing the UNO R4 boards to ...

The Arduino Uno-compatible board has an MCS-51 (often called 8051 instead) instead of the usual ATmega328P/ATmega168. Specifically, [ElectroBoy] uses the AT89S52.