Reading a Push Button Toggle

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!