Arduino Uno is a board that uses the ATmega328 microcontroller. Arduino Uno has 14 digital pins (6 pins can be used as PWM outputs), 6 analog inputs, a 16 MHz crystal oscillato, an USB connection, a voltage source connector, an ICSP header, and a reset button. Arduino Uno contains everything needed to support a microcontroller. Only by connecting it to a computer via USB or providing a DC voltage from the battery or AC adapter to DC can it work. Arduino Uno uses ATmega16U2 which is programmed as a USB to serial converter for serial communication to computers via a USB port.

Uno differs from all previous boards in that it is a USB-to-serial connection using the Atmega8U2 feature programmed as a USB-to-serial converter, different from the previous board that uses a USB-to-serial FTDI chip driver.

The name “Uno” means one in Italian, to mark the launch of Arduino 1.0. Uno and version 1.0 will be the reference version of Arduino. Uno is the latest in a series of Arduino USB boards, and as a reference model for the Arduino platform, for comparison with previous versions, see the Arduino board index.


ATmega328 microcontroller
5V Voltage operation
Input Voltage (recommended) 7-12V
Input Voltage (limit) 6-20V
Digital I / O Pins 14 (where 6 provides PWM output)
Analog Input Pin 6
Current DC per I / O Pin 40 mA
Current 3.3V Pin 50 mA DC
32 KB Flash Memory (ATmega328) which is 0.5 KB used by the bootloader
SRAM 2 KB (ATmega328)
EEPROM 1 KB (ATmega328)
16 MHz Clock Speed


Uno Arduino can be activated via a USB connection or with an external (automatic) power supply.

External (non-USB) power can come from either the AC-to-DC adapter or the battery. This adapter can be connected by plugging a center-positive plug jack of a 2.1mm size POWER connector. The tip of the head of the battery can be inserted into the Gnd and Vin pin header of the POWER connector.

The recommended range of power requirements for Uno boards is 7 to 12 volts. If powered by less than 7 volts the Unv pin may be 5v operating but is unstable then if the power is more than 12V, the voltage regulator can overheat and can damage the Uno board.

Electric pins are as follows:

VIN. The input voltage to the Arduino board when it uses an external power source (instead of a 5 volt USB connection or other power source).

5V. The power supply is used to power the microcontroller and other components.

3v3. A 3.3 volt supply is generated by an on-board regulator.

GND. Ground pin.


ATmega328 has 32 KB (with 0.5 KB used for bootloaders), 2 KB of SRAM and 1 KB of EEPROM (which can be read and written with EEPROM liberary).

Input and Output

Each of the 14 digital pins on Uno can be used as input or output, using the pinMode (), digitalWrite (), and digitalRead () functions, operating at 5 volts. Each pin can give or receive a maximum of 40 mA and has an internal pull-up resistor (by default interrupted) of 20-50 kOhms. In addition, some pins have special functions:

Serial: 0 (RX) and 1 (TX). Used to receive (RX) and transmit (TX) TTL serial data. This pin is connected to the pin associated with the Serial ATmega8U2 USB-to-TTL chip.

External interrupts: 2 and 3. These pins can be configured to trigger interrupts at low values, with edge constraints rising or falling, or changing values. See (attachInterrupt) function for further details.

PWM: 3, 5, 6, 9, 10, and 11. Provides 8-bit PWM output with analogWrite () function.

SPI: 10 (SS), 11 (Motion), 12 (MISO), 13 (SCK). This pin supports SPI communication using the SPI library.

LEDs: 13. There is a built-in LED connected to a digital pin 13. When the pin is HIGH, LED is on, when the pin is LOW, the LED is off.

Uno has 6 analog inputs, labeled A0 through A5, each of which provides 10 bits with a resolution (ie 1024 different values). In addition, some pins have special functions:

I2C: A4 (SDA) and A5 (SCL). Support I2C (TWI) communication using the Wire library.

Aref. Reference voltage (0 to 5V only) for analog input. Used with the analogReference () function.

Reset Bring this line LOW to reset the microcontroller.

See also Arduino pin mapping and ATmega328 port.


Uno Arduino has a number of facilities for communicating with computers, other Arduino, or other microcontrollers. ATmega328 provides UART TTL (5V) for serial communication, which is available on digital pins 0 (RX) and 1 (TX). An ATmega8U2 as a serial communication channel via USB and as a virtual com port for software on a computer. Firmware ‘8 U2 uses a standard COM USB driver, and no external drivers are needed. However, on Windows it is needed, an inf file. The Arduino software has a serial monitor that allows it to be used to monitor simple textual data that will be sent to or from the Arduino board. The RX and TX LEDs on the board will blink when data is being sent via a USB-to-serial chip with a USB connection to the computer (but not for serial communication on pins 0 and 1).

A Software Serial library makes it possible to communicate serially on one of the digital pins on Uno’s board.

ATmega328 also supports I2C (TWI) and SPI communication. The Arduino software includes the Wire library to simplify the use of the I2C bus, see documentation for details. For SPI communication, use the SPI library.

Arduino uno can be powered via a USB (Universal SerialBus) connection or through an external power supply. If Arduino Uno is connected to both of these resources together, Arduino Uno automatically selects one of the resources for use. External power supply (which is not via USB) can come from an AC to DC adapter or a battery. The adapter can be connected to the power socket on the Arduino Uno. If using a battery, the end of the cable connected to the battery is inserted into the GND pin and the Vinyang is on the power connector. Arduino uno can operate at voltages of 6 to 20 volts. If the Arduino Uno is voltage below 7 volts, then the 5V pin on the Arduino board will provide voltages below 5 volts and this may cause the Arduino Uno to work unstable. If a voltage exceeds 12 volts, the voltage stabilizer is likely to overheat and damage arduino uno.The recommended voltage given to arduino uno ranges from 7-12 volts. The power supply pins are as follows:

Vin is the pin to supply the voltage to Arduino Uno when using an external power source (other than a USB connection or other regulated power sources). A voltage source can also be provided through this pin if the power source used for Arduino Uno is supplied through the power socket. 5V is a pin that provides a regulated voltage of 5 volts from the voltage regulator on Arduino Uno.
3V3 is a pin that provides a regulated voltage of 3.3 volts from the voltage regulator on Arduino Uno.
GND is a ground pin.

0/5 (0 Reviews)


Please enter your comment!
Please enter your name here