Push buttons are very simple to use in analog circuits as switches. Pushing the button simply means a close circuit and letting it go back to rest is an open circuit, under the assumption of a normally open push button switch. However, the use of a push button goes beyond as a simple switch when an Arduino or any microcontroller is involved.

An Arduino can read the input signals of a push button switch and act accordingly. In addition, it can store this value and act as a 'programmed toggle flip-flop.' However, this particular use case for reading a push button switch may not be quite as intuitive to make as expected. As such, the focus of this project is the proper use and wiring for a digital reading of a push button to be used to toggle multiple colours of an RGB LED!

Step 1: Tools and Materials

Arduino 101 or Arduino Uno
Breadboard
Push Button Switch
RGB LED
3 pieces of 100Ω resistors
Jumper Wires

Step 2: Circuitry

Connecting the Arduino Power to the Breadboard

Connect the 3.3V pin of the Arduino to the red power rail of the breadboard.
Connect the GND pin of the Arduino to the black power rail of the breadboard.

Wiring the Push Button

Connect a 10K Ω resistor from one of the pins of the Push Button Switch to the red power rail of the breadboard.
Connect the same pin above to the digital pin 3 of the Arduino.
Connect the other pin on the same side to the ground rail of the breadboard.

Lastly, connect the RGB LED to the Arduino.

Connect the longest pin of the RGB to the common ground rail of the breadboard.
Connect the remaining three pins to a 100Ω resistor in series to pins 9, 10, 11 respectively.

Step 3: Code

const int buttonPin = 3;

 //RGB LED pins  const int redPin = 11;      const int greenPin = 10;  const int bluePin = 9;

//create a variable to store a counter and set it to 0 int counter = 0; void setup() {   // Set up the pushbutton pins to be an input:   pinMode(buttonPin, INPUT);

  // Set up the RGB pins to be an outputs:   pinMode(redPin, OUTPUT);     pinMode(greenPin,OUTPUT);   pinMode(bluePin,OUTPUT); }

void loop() {  // local variable to hold the pushbutton states   int buttonState;

  //read the digital state of buttonPin with digitalRead() function and store the           //value in buttonState variable   buttonState = digitalRead(buttonPin);

  //if the button is pressed increment counter and wait a tiny bit to give us some          //time to release the button   if (buttonState == LOW) // light the LED   {     counter++;     delay(150);   }

  //use the if satement to check the value of counter. If counter is equal to 0 all         //pins are off   if(counter == 0)   {    digitalWrite(redPin,LOW);    digitalWrite(greenPin,LOW);    digitalWrite(bluePin,LOW);   }

  //else if counter is equal to 1, redPin is HIGH   else if(counter == 1)   {    digitalWrite(redPin,HIGH);    digitalWrite(greenPin,LOW);    digitalWrite(bluePin,LOW);   }

  //else if counter is equal to 2 greenPin is HIGH   else if(counter ==2)   {    digitalWrite(redPin,LOW);    digitalWrite(greenPin,HIGH);    digitalWrite(bluePin,LOW);   }

  //else if counter is equal to 3 bluePin is HIGH   else if(counter ==3)   {    digitalWrite(redPin,LOW);    digitalWrite(greenPin,LOW);    digitalWrite(bluePin,HIGH);   }

  //else reset the counter to 0 (which turns all pins off)   else   {    counter =0;   } }

Step 4: Demo

As I push the push-button, it first toggles to red, then green, then blue, and finally off. This cycles through all the colours as only 1 push button is pressed!