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Arduinos: Home

Physical Computing, the Internet of Things, Sensors and Servos

Simple Circuits

Breadboards and Jumper Wires

Using a solderless breadboard is one way to build impermanent prototypes. While soldering may be of use later, jumper wires are used to make connections between the pins on the Arduino and the components of your build. Both the Arduino pins and the holes in the breadboard are conductive, allowing for the use of male-to-male jumper wires with a colored plastic coating and insulated terminals. (To learn about other types of jumper wires, see

The breadboard allows for connections of multiple components without physically attaching the individual pieces. Based on the diagram provided above, our breadboard's connections run vertically, but do not bridge the divide in the middle. (For more info on breadboards, see

When you have advanced in learning about Arduinos, learn more about soldering and safety with or or .

Arduino Uno

The Arduino Uno is a single-board microcontroller, and is the standard in the Arduino suite of microcontrollers. (For more information on other types of boards like the Mega, Mini, Lilypad, etc. and their functionalities, please visit

The Arduino Uno has a USB port to connect to your laptop. You will need a USB cable type A/B. It also has a slot for external power supply.

You will notice that the Arduino has 32 holes, which are called pins. The bases of each pin are conductive.

The Arduino Uno has 14 digital pins (0-13). Digital pins can operate as inputs or outputs, but default to INPUT. Pins set to OUTPUT provide enough current to brightly light an LED. Because so much current is produced through OUTPUT, it is recommended to use a resistor. 

  • 6 of the digital pins can produce pulse width modulation, and are labeled with a tilde (~). Pulse width modulation allows the microcontroller to create analog values through digital means, and requires the function analogWrite(). 
  • Digital pin 13 is special because it has a surface mount LED already connected on the Arduino, and is regularly used as a test that the Arduino is working or as an indicator for the beginning part of any code.
  • Serial communication occurs using digital pins 0RX (receive) and 1TX (transmit). (For more info, see )

The Arduino Uno has 6 analog pins(A0-A5). Analog pins default to INPUT, usually for reading analog sensors, but can perform the same tasks as digital pins. To distinguish them from the digital pins in the code, they are labeled with an A (e.g., A3). The Arduino has a 6 channel analog-to-digital converter and any input read from the analog pins will be converted to a number on a scale of 0 to 1023.

The Arduino Uno has a reset button which erases the code previously loaded. It also has a reset pin if you need to reset in the middle of your sketch.

The Arduino Uno has 3 dedicated ground (GND) pins (though any pin can be coded to ground), which grounds the circuit without requiring code. To provide power, there is a 3.3 volt (V) pin and a 5V pin. 

The AREF pin is used for analogReference() (For more information, see here AREF )

Resistor Color Code Chart

Subject Guide

Sara Gonzalez's picture
Sara Gonzalez
University of Florida Home Page

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