We use Arduino Uno as an example to illustrate the main circuit components of an Arduino board. Figure below shows the name of components. Table 1 shows the explanation for each component.
Arduino Uno board cited from Nasreen, Sanjida & Rokunuzzaman, Md & Biswas, Samarjith. (2017). Assessment of Surface Roughness Using LVDT: A Convenient and Inexpensive Way of Measuring Surface Irregularities.
| Components | Function |
| USB Plug | connect to computer with USB cable for loading code. Also, can be used to power Arduino |
| External Power Supply | supply Arduino power from external power such as batter pack. It also is called as “Barrel Jack”. You can power your Arduino either through USB or Barrel Jack. |
| Serial In (RX) & Serial Out (TX) | These two pins are used to setup a serial communication with other devices such as a second Arduino. You can learn more detail about serial communication here |
| Analog In Pins | The area of pins under the ‘Analog In’ label (A0 through A5 on the Uno) are Analog In pins. These pins can read the signal from an analog sensor (like a temperature sensor) and convert it into a digital value. |
| Digital Pins | Digital pins (0 through 13 on the Uno) can be used for both digital input (like telling if a button is pushed) and digital output (like powering an LED). |
| PWM | Some of digital pins have the tilde (~) next to it. These pins (Pin 3, 5, 6, 9, 10, 11 on the Uno) have a special output function called Pulse-Width Modulation (PWM). You can learn more detail about PWM here |
| Ground Pins | These pins are labeled as “GND” on the board. There are several GND pins on the Arduino. Any of them can be used to ground your circuit with Arduino. |
| Voltage In Pin | This pin is labeled as “vin” on the board. You can use it and a GND pin to power Arduino. |
| 5V/3.3V Pins | The 5V pin supplies 5 volts of power and the 3.3V pin supplies 3.3 volts of power. You can use them to supply power to simple low-power components. |
| Analog Reference Pin | This pin is labeled as “AREF” on the board. Most of the time you can leave this pin alone. It is sometimes used to set an external reference voltage (between 0 and 5 Volts) as the upper limit for the analog input pins. |
| Reset Button/Pin | You can use reset button to reinitialize Arduino board by pushing it. You can also use reset pin to reset Arduino board though other control circuits. |