Each of the 14 digital pins on the Arduino Uno can be used as an input or output ... These pins are connected to the corresponding pins of the ATmega8U2 USB-to-TTL Serial chip. PWM: 3, 5, 6, 9, 10, ...

The Arduino Uno Rev3 is the third revision of ... off or disconnected from the main supply. The VRTC pin supports anything between 1.6V and 3.3V, so using two AA batteries would be fine.

Arduino boards can most ... two power output pins (3.3V and 5V) for powering your circuit, and a reset pin for connecting a push button to reset the UNO in case you can't use the one on-board.

The Uno also has a limited number of pins, making it difficult to work with when the project requires plenty of input and output components. However, these two areas are where the Arduino Mega shines.

Retaining the Arduino UNO form factor shield compatibility and 5V operating voltage yet powered by a 32-bit Cortex-M4 and a 3-to-16x increase in clock speed, memory and flash storage. Arduino will ...