Arduino

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An Arduino is an electronic open-source prototyping platform that uses micro controller for processing, like a small simple computer.

There are a few models of Arduinos.  You may choose one or the other based on the number of inputs and outputs, integrated MCU (Micro Controller Units) and portability.

To add extra functionality you may purchase shields, which are basically boards that give extra functionality for the Arduino board such as Ethernet and WI-fi capabilities, SD card reading,  motor shield (e.g. robots) and many others.

An Arduino has a number of  “pins” which can be connected, with wires,  to other devices to provide input an output. Pins must be configured as input, output, digital, and analog through software placed on the Arduino. Not all pins are hardwired with PWM (Pulse width Modulation) but almost all pins can be assigned as analog input or output to control voltage.

There are two types of inputs: digital and analog

  • A digital input has only two states, on and off (0 or 1).
  • Digital inputs are the best choice for buttons and switches.
  • A resistor is used when connecting a button or switch to a digital input. 10k is a common value for this “pull-up” or “pull-down” resistor and for debounce procedures.  (See Ohms Law bellow).
  • An analog input can detect continuous sources: knobs faders, amount of light, sound pressure, proximity, capacitance, etc. Often these are simple variable resistors and connecting them between ground and a pin configured as an analog input is sufficient.

Microcontrollers have similar types of outputs: analog and digital

  •  A digital output is used to switch something on and off, commonly this is an LED, but anything can be turned on and off.
  • If the device you are switching requires significant amounts of power (more than a small battery could produce), a relay must be used.
  • For using power sources with less than 12V you can use a Linear Voltage Regulator.
  • Arduino can’t really produce analog signals, only digital. But a technique called Pulse Width Modulation (PWM) can emulate analog signals through controlling the voltage. The output is turned on and off very quickly (thousands of time per second) by varying the duty cycle, how long the output is up vs. down, the output voltage is changed  “smoothly”.

Between input and output the Arduino can take the input data and programmatically respond to it by changing outputs.

The program that resides on the Arduino is called a Sketch.

Arduino sketches (programs) are written on the computer and uploaded to the Arduino using an the Arduino IDE (Integrated Development Environment). There are many sample sketches, designed to work with simple circuits, included with the Arduino IDE.

Arduinos can run autonomously from a computer by relying on its internal programming.

This is great for creating small robots or simple button and LED games, or fun clocks etc.

For many artists an Arduino is a way to add inputs to a computer and in the final usage will be connected to a computer. An Arduino communicates to a computer via a USB cable. It can also receive its power through the USB cable. In this way it can be used to create custom control surfaces for computer based programs.

When it is used with a computer, the Arduino shows up on the computer as a modem or a serial interface. Because the interfaces of most modern computers rely on parallel forms of communication you may have to install additional software for communicating through serial ports using your USB ports.

“Serial” is a type of communication where a single piece of information is sent at a time. Data between an Arduino and a computer relies on a serial protocol. The “baud rate” is the speed of that communication (the number of individual messages sent per second).

In the Arduino software the “serial monitor” allows you to see the information passing between Arduino and the computer. This is a very important troubleshooting tool, and many initial projects focus on interacting with a sensor connected to an input on the Arduino and seeing, in the serial monitor, the messages getting passed to the computer. It is strangely thrilling to turn a knob connected to a circuit board and see numbers in the serial monitor go from 0 to 1023!

The simplest thing to configure is an analog input with a potentiometer (knob). From the potentiometer, connect one side to ground (there are a few ground pins which provide an absolute “0” for all circuits to relate to), the middle to an analog input pin, and the other side to a +5 V pin.  Analog I/O is is a great first tutorial to try out, and it contains an excellent explanation of why the circuit works, with pictures even!

Datasheets

Another important aspect of working with Arduino and electronics is to be able to read and interpret the basics of components Datasheets and Circuit Schematics. Datasheets are documents that summarizes the performance and technical characteristics of a given electronic component. In simple terms It basically tells you what’s necessary to connect the electronic component correctly on your Arduino.  So, in order to pick the correct resistor, or choose the correct voltage, current and avoid burning all those expensive LEDs strips that you bought for your project, its a good idea to check the datasheet first.

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For more on Datasheets see:

Circuit Schematics

Circuit Schematics or Circuit Diagram is a simplified conventional graphical representation of an electronic circuit.

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For more on Circuit Schematics see:

To purchase Arduino’s and the related sensors, LEDs, wires, etc., check out these websites:

The Basics of Electronics for Arduino

Here are some important theory you may need to know when working with Arduino or other physical computing boards.

Ohms Law

Ohm’s law states that the current through a conductor between two points is directly proportional to the potential difference across the two points. Introducing the constant of proportionality, the resistance

In the Basic Electronic Tutorial page you can find a wide variety of information about electronic components an systems.

Reading Resistor Values

The electronic color code is used to indicate the values or ratings of electronic components, very commonly for resistors, but also for capacitors, inductors, and others.

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