In some cases you need to display a static text with different colors, for this purpose you can use RGB LED Strips. In this tutorial we will learn how to interface RGB LED strip with arduino and drive it using ULN2003.

This is a basic tutorial for using Common Anode RGB LED Strip, PWM, and switch. By the end, you will have single switch to control colors of the LED strip. Connect the LED’s anode lead to +12V and connect the 3 RGB cathode leads to digital pins 9, 10, 11 through ULN2003 respectively.

RGB LED Strip Connections with Arduino

To drive complete RGB LED Strip we have used ULN2003 as a driver circuit, LED strip works at 12V. You can combine ULN2003 driver outputs to get more current.

Arduino Code for RGB LED Color Control

//=========================================================================
//         RGB LED Color Control
//         circuits4you.com
//=========================================================================
// constants won't change. They're used here to 
// set pin numbers:
const int buttonPin = 7;     // the number of the pushbutton pin
const int BLUEledPin =  11;      // LED pin
const int REDledPin =  10;      // LED pin
const int GREENledPin =  9;      // LED pin

// variables will change:
int buttonState = 0;         // variable for reading the pushbutton status
int color=0;
//=========================================================================
//              SETUP
//=========================================================================
void setup() {
  // initialize the LED pin as an output:
  pinMode(BLUEledPin, OUTPUT);  
  pinMode(REDledPin, OUTPUT);
  pinMode(GREENledPin, OUTPUT);
  
  // initialize the pushbutton pin as an input:
  pinMode(buttonPin, INPUT);     
  digitalWrite(buttonPin, HIGH); //Activate internal pull up for switch
}
//=========================================================================
//                         LOOP
//=========================================================================
void loop(){
  // read the state of the pushbutton value:
  buttonState = digitalRead(buttonPin);

  // check if the pushbutton is pressed.
  // if it is, the buttonState is HIGH:
  if (buttonState == LOW) {     
    delay(300);
    color++;
    if(color>10)
    {color=0;}
  } 
  
  //Set different color values refer HTML Color codes
  switch (color)
  {
    case 0:
      SetColor(255,0,0);
    break;
    case 1:
      SetColor(255,255,0);
    break;
    case 2:
      SetColor(0,0,255);
    break;
    case 3:
      SetColor(128,128,20);
    break;
    case 4:
      SetColor(0,255,255);
    break;
    case 5:
      SetColor(55,100,100);
    break;
    case 6:
      SetColor(0x00,0xA8,0xA9);
    break;
    case 7:
      SetColor(0xCC,0x66,0x66);
    break;
    case 8:
      SetColor(0x12,0xA2,0x7E);
    break;
    case 9:
      SetColor(0xF0,0x80,0x32);
    break;    
    case 10:
      SetColor(0x30,0xFF,0xFF);
    break;    
  }
}
//=========================================================================
//                   Write Color Value
//=========================================================================
void SetColor(char R,char G,char B)
{
  analogWrite(REDledPin,R);
  analogWrite(GREENledPin,G);
  analogWrite(BLUEledPin,B);  
}

Results

Press switch and see that we have around ten different colors; You can change the color using SetColor(R,G,B). try different values of RGB.