The Arduino is a prototyping platform for electronics that makes it simple to create fun and useful projects, learn about electronics, and quickly test new ideas. In this tutorial, we will look at each component of the Arduino Uno's PCB in detail to gain a better understanding of how the Arduino operates at the hardware level.

MICROCONTROLLER ATMEGA328

The ATMEGA328 microcontroller is at the heart of the Arduino. The ATMEGA328 was designed for industrial automation systems and requires sophisticated electrical engineering and programming abilities to deal with directly. The Arduino was created to simplify programming and attaching devices to the ATMEGA328 microcontroller.


The ATMEGA328 microprocessor is connected to the PCB via a female pin socket and can be removed:

PIN GPIO

The pins on the board's top and bottom are general-purpose input and output (GPIO) pins. External circuits, sensors, and other devices are connected to the Arduino using GPIO pins:


DIGITAL PINS 

Digital pins can supply an external component or device with a high (5V) or low (0V) signal. Some of the digital pins have unique capabilities that will be discussed further below. The digital pins are numbered 0 through 13:


PINS ANALOG

Any voltage between 0V and 5V can be generated or detected via the analog pins. They are numbered from A0 through A5:

PINS FOR POWER AND GROUND

External devices and circuits can be supplied with 5 or 3.3 volts via the power and ground pins:

PINS FOR SDA AND SCL

For I2C communication, the SDA and SCL pins are used:

PINS FOR TX AND RX

For UART communication, the TX and RX pins are used:

PINS FOR MODULATING PULSE WIDTH

The pins with squiggly lines are for pulse width modulation:


BUTTON RESET

The reset button restarts the Arduino and causes the sketch to begin again:


OSCILLATOR OF CRYSTAL

The crystal oscillator allows the Arduino to retain time as well as create pulse width modulation and serial communication signals. Because the crystal oscillator is 16 Mhz, the Arduino can execute binary instructions at 16 Mhz or 16 million times per second:


POWER SOURCE

The power supply is located on the Arduino's PCB on the lower left side:


JACK FOR POWER INPUT

The Arduino can be powered using the USB cable's 5V supply. However, if you want to use the Arduino without a computer, you can use a 7 to 12V AC to DC power supply adapter. The power adapter is linked to the Arduino through the power input jack:


CAPACITORS FOR DECOUPLING POWER SUPPLY

The power supply decoupling capacitors filter the incoming power supply to prevent voltage spikes from damaging the board:


REGULATOR OF VOLTAGE

The voltage regulator reduces the 7 to 12-volt input power to 5 volts, which is the Arduino's working voltage:


USB PORT CONNECTOR

Using USB connectivity, programs are uploaded from your computer to the Arduino. When serial data is displayed on the serial monitor, it is also transmitted over a USB to your computer. While linked to your computer, the USB cord can also power the Arduino. The USB cable connector is as follows:

CHIP FOR USB CONTROL

An ATMEGA16U2 microcontroller serves as the USB controller chip. It manages all of the Arduino's USB communications with your computer:

PINS FOR USB CONTROL CHIP PROGRAMMING

This collection of pins is the USB controller's in-circuit serial programming header (ICSP header). These pins are used to program and re-flash the ATMEGA16U2's firmware:

PINS FOR ATMEGA328 PROGRAMMING

These pins are ATMEGA328's ICSP pins. They are used to program and re-flash the ATMEGA328's firmware:

LED PIN 13

This is a surface-mounted LED linked to digital pin 13. The LED will light up whenever pin 13 is in a high-voltage state:

TX AND RX LIGHTS

When data is transmitted between the Arduino and your computer, the TX and RX LEDs light up:

LED POWER

When the Arduino is powered up, the power LED illuminates: