Basics of Arduino UNO Board

What is Arduino UNO Board?

Arduino UNO Board or Genuino UNO Board is an open-source microcontroller board based on ATmega328p chip. Arduino UNO features 14 digital I/O pins (6 pins can be used as PWM), 6 analog inputs, a 16 MHz quartz crystal, a USB connection, Power Jack and a Reset Button.

Basic Hardware of Arduino/Genuino UNO

Hardware Information of Arduino Uno



Arduino/Genuino UNO Board contains

  1. Micro-controller (ATmega328P) – Micro-controller used in Arduino is ATmega328P (a single chip micro-controller) created by Atmel. It has 32KB programmable flash memory, 2KB SRAM, 1KB EEPROM (Electrically Erasable Programmable Read-Only Memory). ATmege328P micro-controller operates between 1.8 to 5.5 volt. It contains 26 input/output pins in which there are 23 general purposes I/O lines.
  2. USB Connector – USB connector is used for two purposes in Arduino. First one is to load user program to Arduino using Arduino IDE and another one is to power Arduino Board. For uploading program to board Click here.
  3. Power Port – The Arduino can be powered using AC to DC adapter or battery. 2.1mm center-positive plug is used to power the Arduino Board. Recommended input power Voltage is 7-12V.
  4. USB Interface Chip – Arduino has Atmel ATmega16U2 as USB interface chip. It is a bridge between Computer’s USB Port and the main processor’s serial port.
  5. Digital I/O Pins – In Arduino UNO board 14 Digital I/O Pins. The 14 Digital I/O Pins are numbered from Pin 0 to Pin 13. In which 6 of them are PWM (Pulse-Width Modulation) Digital I/O Pins. Pin no 3, 5, 6, 9, 10, and 11 are PWM Pins which are marked as (~) symbol on the board. PWM pins are used to simulate analog output. Digital I/O Pins are used to take Digital Input or provide Digital Output in Arduino UNO Board.
  6. Analog Input Pins – In Arduino UNO board 6 Analog Input Pins. The 6 Analog Input Pins are numbered from Pin A0 to Pin A5. Analog Input Pins are used to take the signal from analog sensors and convert it into a digital value. The pins measure the voltage not current because it has a very high value of internal resistance. So, the value of current is much smaller as compared to the voltage.
  7. Power Pins
    • Vin – The input voltage to the Arduino/Genuino board when it’s using an external power source.
    • 5V – This pin outputs a regulated 5V from the regulator on the board. Supplying voltage via the 5V or 3.3V pins bypasses the regulator, and can damage your board. We don’t advise it.
    • 3V3 – This pin outputs a regulated 3.3 volt supply generated by the onboard regulator. Maximum current draw from this pin is 50 mA.
    • GND – Ground pins.
    • IOREF – This pin on the Arduino/Genuino board provides the voltage reference with which the microcontroller operates. A properly configured shield can read the IOREF pin voltage and select the appropriate power source or enable voltage translators on the outputs to work with the 5V or 3.3V.
  8. Voltage Regulator – Main work of Voltage Regulator is to regulate the input and output voltage of Arduino UNO board. It also regulates the voltage for 5V and 3V3 pins. If power voltage of power port is more than 12V, the voltage regulator may overheat and damage the board.
  9. Master Reset Button – Master Reset Button is used to reset the Arduino UNO board and restart the running program from starting. It is useful when the programmer wants to run the program from the starting point. When Master Reset Button is pressed, it sends the logical pulse to reset pin of micro-controller.
  10. ICSP Header Pins – a Full form of ICSP is In-Circuit Serial Programming also called as In-System Programming (ISP). It is used to program AVR microcontrollers. You can use the Arduino ISP to upload sketches directly on the AVR-based Arduino boards without the need of the bootloader ICSP Header Pins contains six pins MISO(Master In Slave Out), +Vcc, SCK(Serial Clock), MOSI(Master Out Slave In), Reset, GND.
  11. RX/TX LED – The RX and TX LEDs on the board will flash when data is being transmitted via the USB-to-serial chip and USB connection to the computer.

Content and image source: arduino.cc

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