Arduino UNO Pinout Diagram

The Arduino UNO is arguably the most popular Arduino board currently available. This Arduino UNO Pinout diagram reference will hopefully help you get the most out of this board:
Download Arduino UNO Pinout PDF:
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Arduino UNO Pinout Description
The Arduino UNO board is divided into digital pins, analog pins and power pins. There are pins with secondary functions as listed below. Secondary pins are mostly communications pins such as I2C and SPI.
Digital Pins
[one_fourth]Pin Name[/one_fourth][one_fourth]Description[/one_fourth][one_fourth]Secondary Function[/one_fourth][one_fourth_last]Description[/one_fourth_last]
[one_fourth]D0[/one_fourth][one_fourth]Digital Pin 0[/one_fourth][one_fourth]RX[/one_fourth][one_fourth_last]Receive pin for Serial UART[/one_fourth_last]
[one_fourth]D1[/one_fourth][one_fourth]Digital Pin 1[/one_fourth][one_fourth]TX[/one_fourth][one_fourth_last]Transmit pin for Serial UART[/one_fourth_last]
[one_fourth]D2[/one_fourth][one_fourth]Digital Pin 2[/one_fourth][one_fourth]INT0[/one_fourth][one_fourth_last]Interrupt Pin 0[/one_fourth_last]
[one_fourth]D3[/one_fourth][one_fourth]Digital Pin 3[/one_fourth][one_fourth]INT1[/one_fourth][one_fourth_last]Interrupt Pin 1[/one_fourth_last]
[one_fourth]D4[/one_fourth][one_fourth]Digital Pin 4[/one_fourth][one_fourth][/one_fourth][one_fourth_last][/one_fourth_last]
[one_fourth]D5[/one_fourth][one_fourth]Digital Pin 5[/one_fourth][one_fourth][/one_fourth][one_fourth_last][/one_fourth_last]
[one_fourth]D6[/one_fourth][one_fourth]Digital Pin 6[/one_fourth][one_fourth][/one_fourth][one_fourth_last][/one_fourth_last]
[one_fourth]D7[/one_fourth][one_fourth]Digital Pin 7[/one_fourth][one_fourth][/one_fourth][one_fourth_last][/one_fourth_last]
[one_fourth]D8[/one_fourth][one_fourth]Digital Pin 8[/one_fourth][one_fourth][/one_fourth][one_fourth_last][/one_fourth_last]
[one_fourth]D9[/one_fourth][one_fourth]Digital Pin 9[/one_fourth][one_fourth][/one_fourth][one_fourth_last][/one_fourth_last]
[one_fourth]D10[/one_fourth][one_fourth]Digital Pin 10[/one_fourth][one_fourth]SS[/one_fourth]SPI Slave Select Pin[one_fourth_last][/one_fourth_last]
[one_fourth]D11[/one_fourth][one_fourth]Digital Pin 11[/one_fourth][one_fourth]MOSI[/one_fourth][one_fourth_last]SPI Master Out-Slave In[/one_fourth_last]
[one_fourth]D12[/one_fourth][one_fourth]Digital Pin 12[/one_fourth][one_fourth]MISO[/one_fourth][one_fourth_last]SPI Master In-Slave Out[/one_fourth_last]
[one_fourth]D13[/one_fourth][one_fourth]Digital Pin 13[/one_fourth][one_fourth]SCK[/one_fourth][one_fourth_last]SPI Clock[/one_fourth_last]
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Analog Pins
[one_fourth]Pin Name[/one_fourth][one_fourth]Description[/one_fourth][one_fourth]Secondary Function[/one_fourth][one_fourth_last]Description[/one_fourth_last]
[one_fourth]A0[/one_fourth][one_fourth]Analog Pin 0[/one_fourth][one_fourth][/one_fourth][one_fourth_last][/one_fourth_last]
[one_fourth]A1[/one_fourth][one_fourth]Analog Pin 1[/one_fourth][one_fourth][/one_fourth][one_fourth_last][/one_fourth_last]
[one_fourth]A2[/one_fourth][one_fourth]Analog Pin 2[/one_fourth][one_fourth][/one_fourth][one_fourth_last][/one_fourth_last]
[one_fourth]A3[/one_fourth][one_fourth]Analog Pin 3[/one_fourth][one_fourth][/one_fourth][one_fourth_last][/one_fourth_last]
[one_fourth]A4[/one_fourth][one_fourth]Analog Pin 4[/one_fourth][one_fourth]SDA[/one_fourth][one_fourth_last]I2C Data Out[/one_fourth_last]
[one_fourth]A5[/one_fourth][one_fourth]Analog Pin 5[/one_fourth][one_fourth]SCL[/one_fourth][one_fourth_last]I2C Clock[/one_fourth_last]
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Power Pins
[one_half]Pin Name[/one_half][one_half_last]Description[/one_half_last]
[one_half]5V[/one_half][one_half_last]5V (Regulated) Source[/one_half_last]
[one_half]3.3V[/one_half][one_half_last]3.3V Source[/one_half_last]
[one_half]GND[/one_half][one_half_last]Ground[/one_half_last]
[one_half]RESET[/one_half][one_half_last]Reset[/one_half_last]
[one_half]Vin[/one_half][one_half_last]DC Jack Input Voltage[/one_half_last]
[one_half]IOREF[/one_half][one_half_last]I/O Reference Voltage. This pin is connected to 5V for the UNO[/one_half_last]
[one_half]AREF[/one_half][one_half_last]ADC Reference Voltage. Insert other voltage (0-5V only) to use as reference for analog conversions[/one_half_last]
Also notice that the ATMega pins for each Arduino pin are also provided in the diagram above. For details on how to use these pins, see Arduino Port Manipulation.
Arduino UNO Rev3 Schematic Diagram
For those who want to dig deeper into understanding the Arduino UNO board, I suggest you look into its schematic diagram:
The schematic diagram above is also helpful when you want to build your own Arduino.
Download Arduino UNO Schematic PDF:
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