The Arduino Uno is a microcontroller board based on the ATmega328 .
It has 14 digital input/output pins (of which 6 can be used as PWM
outputs), 6 analog inputs, a 16 MHz ceramic resonator, a USB connection,
a power jack, an ICSP header, and a reset button. It contains
everything needed to support the microcontroller; simply connect it to a
computer with a USB cable or power it with a AC-to-DC adapter or
battery to get started.
The Uno differs from all preceding boards
in that it does not use the FTDI USB-to-serial driver chip. Instead, it
features the Atmega16U2 (Atmega8U2 up to version R2) programmed as a
Revision 2 of the Uno board has a resistor pulling the 8U2 HWB line to ground, making it easier to put into DFU mode.
Revision 3 of the board has the following new features:
pinout: added SDA and SCL pins that are near to the AREF pin and two
other new pins placed near to the RESET pin, the IOREF that allow the
shields to adapt to the voltage provided from the board. In future,
shields will be compatible with both the board that uses the AVR, which
operates with 5V and with the Arduino Due that operates with 3.3V. The
second one is a not connected pin, that is reserved for future purposes.
- Stronger RESET circuit.
- Atmega 16U2 replace the 8U2.
means one in Italian and is named to mark the upcoming release of
Arduino 1.0. The Uno and version 1.0 will be the reference versions of
Arduino, moving forward. The Uno is the latest in a series of USB
Arduino boards, and the reference model for the Arduino platform