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The Arduino UNO Board

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Vatsal edited this page May 26, 2025 · 4 revisions

Arduino UNO

Arduino UNO is a microcontroller board based on the ATmega328P. It has:

  • 14 digital input/output pins (of which 6 can be used as PWM outputs)
  • 6 analog inputs
  • A 16 MHz crystal oscillator
  • A USB connection
  • A power jack
  • An ICSP header (In-Circuit Serial Programming header)
  • A reset button

Arduino_UNO_board

It contains everything needed to support the microcontroller; simply connect it to a computer with a USB cable or power it with an AC-to-DC adapter or battery to get started.

You can tinker with your UNO without worrying too much about doing something wrong—worst case scenario, you can replace the chip for a few dollars and start over again. It is the perfect board to get familiar with electronics and coding.

Arduino UNO Board Components

Board Pins

1. Power USB

Arduino board can be powered by using the USB cable from your computer. All you need to do is connect the USB cable to the USB connection (1).

2. Barrel Jack

Arduino boards can be powered directly from the AC mains power supply by connecting it to the Barrel Jack (2).

3. Voltage Regulator

The voltage regulator controls and stabilizes the voltage given to the Arduino board. It ensures safe DC voltages are supplied to the processor and other components.

4. Crystal Oscillator

Helps Arduino deal with time-based operations. The frequency of the oscillator is 16 MHz, printed as 16.000H9H on the board.

5. Arduino Reset

You can reset your Arduino board (restart your program) in two ways:

  1. Using the reset button (17) on the board.
  2. Connecting an external button to the RESET pin (5).

6-9. Pins (3.3V, 5V, GND, Vin)

  • 3.3V (6) – Supplies 3.3V output.
  • 5V (7) – Supplies 5V output.
  • GND (8) – Ground pins. Multiple available on the board.
  • Vin (9) – Input voltage to power the board from an external source (like AC adapter).

10. Analog Pins

Arduino UNO has 6 analog input pins: A0 to A5.
These read analog signals (e.g., from sensors) and convert them to digital values for processing.

11. Main Microcontroller

This is the brain of the board – an Atmel IC (usually ATmega328P).
Each Arduino board may have a different microcontroller, so it's important to know which IC is on your board.

12. ICSP Header

Stands for In-Circuit Serial Programming. It includes:

  • MOSI, MISO, SCK, RESET, VCC, GND
    Used for programming the microcontroller or SPI communication.

13. Power LED Indicator

Lights up when the board is powered correctly. If it doesn’t light up, check your power source or connection.

14. TX and RX LEDs

  • TX (Transmit) – Flashes when data is sent.
  • RX (Receive) – Flashes when data is received.
    Located near digital pins 0 (RX) and 1 (TX).

15. Digital I/O Pins

Label: Digital I/O (15)
UNO has 14 digital pins, numbered 0–13.

  • Pins with ~ support PWM output (Pulse Width Modulation).
  • Can be configured as input or output.

16. AREF (Analog Reference)

Stands for Analog Reference.
Used to set an external reference voltage (0–5V) for analog inputs.

Created and maintained by Open Horizon® under the GNU AGPLv3 licence. Visit the full repository at https://github.com/openhorizonrobotics/ece-1.

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