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Arduino Development Cookbook

You're reading from  Arduino Development Cookbook

Product type Book
Published in Apr 2015
Publisher
ISBN-13 9781783982943
Pages 246 pages
Edition 1st Edition
Languages
Concepts
Author (1):
Cornel M Amariei Cornel M Amariei
Profile icon Cornel M Amariei

Table of Contents (16) Chapters

Arduino Development Cookbook
Credits
About the Author
About the Reviewers
www.PacktPub.com
Preface
1. Power on – Arduino Basics 2. Blinking LEDs 3. Working with Buttons 4. Sensors 5. Motor Control 6. More Output Devices 7. Digital Communication with Arduino 8. Hacking Electronics – the Basics Index

Code basics – Arduino pins


The most important feature of the Arduino is its control over digital input/output (I/O) pins. On each pin, we can set a voltage value of 5 V, representing logic HIGH, or 0 V, representing logic LOW. Also, we can read whether a value of 5 V or 0 V is applied externally. Here we will learn how.

Getting ready

For this recipe, ensure that you have the Arduino IDE running on a computer.

How to do it…

The following code turns a pin HIGH and LOW repeatedly while reading the external voltage applied to another:

void setup() {
  // Set pin 2 as a digital Output
  pinMode(2, OUTPUT);
  // Set pin 3 as a digital Input
  pinMode(3, INPUT);
}

void loop(){
    // Set pin 2 HIGH
  digitalWrite(2, HIGH);
  // Wait 100 milliseconds
  delay(100);
  // Set pin 2 LOW
  digitalWrite(2, LOW);
  // Wait 100 milliseconds
  delay(100);
    // Read the value of pin 3 and store it in a variable
  int pinValue = digitalRead(3);
}

How it works…

The code sets two pins in output and input mode and then writes and reads from them. Here is the code breakdown:

In setup(), we use the pinMode() function to set pin number 2 as an output. When we set a pin as an output, we can set that pin as either HIGH (5 V) or LOW (0 V). Also, we set pin number 3 as an input. A pin configured as input can read external voltages applied to it. It can read HIGH if the voltage is around 5 V and LOW if the voltage is close or equal to 0 V:

void setup() {
  // Set pin 2 as a digital Output
  pinMode(2, OUTPUT);
  // Set pin 3 as a digital Input
  pinMode(3, INPUT);
}

In the loop() function, we use the digitalWrite() function to set pin number 2 to HIGH. Then, we wait for 100 milliseconds using the delay() function. This function stops the execution of the code for the specified time, in milliseconds. Thereafter, we set the pin to LOW and wait another 100 milliseconds. In the end, we read the value of pin 3 in a variable:

void loop(){
  
  // Set pin 2 HIGH
  digitalWrite(2, HIGH);
  // Wait 100 milliseconds
  delay(100);
  // Set pin 2 LOW
  digitalWrite(2, LOW);
  // Wait 100 milliseconds
  delay(100);
  
  // Read the value of pin 3 and store it in a variable
  int pinValue = digitalRead(3);
}

Tip

Downloading the example code

You can download the example code files from your account at http://www.packtpub.com for all the Packt Publishing books you have purchased. If you purchased this book elsewhere, you can visit http://www.packtpub.com/support and register to have the files e-mailed directly to you.

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Arduino Development Cookbook
Published in: Apr 2015 Publisher: ISBN-13: 9781783982943
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