The CIRC02 code is not one of the default Arduino sketches. To use it, copy the code from below and paste it into a new Arduino Sketch (ctrl+n/command+n)

/*     ---------------------------------------------------------
 *     |  Arduino Experimentation Kit Example Code             |
 *     |  CIRC-02 .: 8 LED Fun :. (Multiple LEDs)   |
 *     ---------------------------------------------------------
 *  
 *  A few Simple LED animations
 *
 * For more information on this circuit http://tinyurl.com/d2hrud
 *
 */
 
//LED Pin Variables
int ledPins[] = {2,3,4,5,6,7,8,9}; //An array to hold the pin each LED is connected to
                                   //i.e. LED #0 is connected to pin 2, LED #1, 3 and so on
                                   //to address an array use ledPins[0] this would equal 2
                                   //and ledPins[7] would equal 9
 
/*
 * setup() - this function runs once when you turn your Arduino on
 * We the three control pins to outputs
 */
void setup()
{
  
  //Set each pin connected to an LED to output mode (pulling high (on) or low (off)
  for(int i = 0; i < 8; i++){         //this is a loop and will repeat eight times
      pinMode(ledPins[i],OUTPUT); //we use this to set each LED pin to output
  }                                   //the code this replaces is below
 
  /* (commented code will not run)
   * these are the lines replaced by the for loop above they do exactly the
   * same thing the one above just uses less typing
  pinMode(ledPins[0],OUTPUT);
  pinMode(ledPins[1],OUTPUT);
  pinMode(ledPins[2],OUTPUT);
  pinMode(ledPins[3],OUTPUT);
  pinMode(ledPins[4],OUTPUT);
  pinMode(ledPins[5],OUTPUT);
  pinMode(ledPins[6],OUTPUT);
  pinMode(ledPins[7],OUTPUT);
  (end of commented code)*/
}
 
 
/*
 * loop() - this function will start after setup finishes and then repeat
 * we call a function called oneAfterAnother(). if you would like a different behaviour
 * uncomment (delete the two slashes) one of the other lines
 */
void loop()                     // run over and over again
{
  oneAfterAnotherNoLoop();   //this will turn on each LED one by one then turn each off
  //oneAfterAnotherLoop();   //does the same as oneAfterAnotherNoLoop but with 
                             //much less typing
  //oneOnAtATime();          //this will turn one LED on then turn the next one
                             //on turning the 
                             //former off (one LED will look like it is scrolling 
                             //along the line
  //inAndOut();              //lights the two middle LEDs then moves them out then back 
                             //in again
}
 
/*
 * oneAfterAnotherNoLoop() - Will light one LED then delay for delayTime then light
 * the next LED until all LEDs are on it will then turn them off one after another
 *
 * this does it without using a loop which makes for a lot of typing. 
 * oneOnAtATimeLoop() does exactly the same thing with less typing
 */
void oneAfterAnotherNoLoop(){
  int delayTime = 100; //the time (in milliseconds) to pause between LEDs
                       //make smaller for quicker switching and larger for slower
  digitalWrite(ledPins[0], HIGH);  //Turns on LED #0 (connected to pin 2 )
  delay(delayTime);                //waits delayTime milliseconds
  digitalWrite(ledPins[1], HIGH);  //Turns on LED #1 (connected to pin 3 )
  delay(delayTime);                //waits delayTime milliseconds
  digitalWrite(ledPins[2], HIGH);  //Turns on LED #2 (connected to pin 4 )
  delay(delayTime);                //waits delayTime milliseconds
  digitalWrite(ledPins[3], HIGH);  //Turns on LED #3 (connected to pin 5 )
  delay(delayTime);                //waits delayTime milliseconds
  digitalWrite(ledPins[4], HIGH);  //Turns on LED #4 (connected to pin 6 )
  delay(delayTime);                //waits delayTime milliseconds
  digitalWrite(ledPins[5], HIGH);  //Turns on LED #5 (connected to pin 7 )
  delay(delayTime);                //waits delayTime milliseconds
  digitalWrite(ledPins[6], HIGH);  //Turns on LED #6 (connected to pin 8 )
  delay(delayTime);                //waits delayTime milliseconds
  digitalWrite(ledPins[7], HIGH);  //Turns on LED #7 (connected to pin 9 )
  delay(delayTime);                //waits delayTime milliseconds  
 
//Turns Each LED Off
  digitalWrite(ledPins[7], LOW);  //Turns on LED #0 (connected to pin 2 )
  delay(delayTime);                //waits delayTime milliseconds
  digitalWrite(ledPins[6], LOW);  //Turns on LED #1 (connected to pin 3 )
  delay(delayTime);                //waits delayTime milliseconds
  digitalWrite(ledPins[5], LOW);  //Turns on LED #2 (connected to pin 4 )
  delay(delayTime);                //waits delayTime milliseconds
  digitalWrite(ledPins[4], LOW);  //Turns on LED #3 (connected to pin 5 )
  delay(delayTime);                //waits delayTime milliseconds
  digitalWrite(ledPins[3], LOW);  //Turns on LED #4 (connected to pin 6 )
  delay(delayTime);                //waits delayTime milliseconds
  digitalWrite(ledPins[2], LOW);  //Turns on LED #5 (connected to pin 7 )
  delay(delayTime);                //waits delayTime milliseconds
  digitalWrite(ledPins[1], LOW);  //Turns on LED #6 (connected to pin 8 )
  delay(delayTime);                //waits delayTime milliseconds
  digitalWrite(ledPins[0], LOW);  //Turns on LED #7 (connected to pin 9 )
  delay(delayTime);                //waits delayTime milliseconds  
}
 
/*
 * oneAfterAnotherLoop() - Will light one LED then delay for delayTime then light
 * the next LED until all LEDs are on it will then turn them off one after another
 *
 * this does it using a loop which makes for a lot less typing. 
 * than oneOnAtATimeNoLoop() does exactly the same thing with less typing
 */
void oneAfterAnotherLoop(){
  int delayTime = 100; //the time (in milliseconds) to pause between LEDs
                       //make smaller for quicker switching and larger for slower
 
//Turn Each LED on one after another
  for(int i = 0; i <= 7; i++){
    digitalWrite(ledPins[i], HIGH);  //Turns on LED #i each time this runs i
    delay(delayTime);                //gets one added to it so this will repeat 
  }                                  //8 times the first time i will = 0 the final
                                     //time i will equal 7;
 
//Turn Each LED off one after another
  for(int i = 7; i >= 0; i--){  //same as above but rather than starting at 0 and counting up
                                //we start at seven and count down
    digitalWrite(ledPins[i], LOW);  //Turns off LED #i each time this runs i
    delay(delayTime);                //gets one subtracted from it so this will repeat 
  }                                  //8 times the first time i will = 7 the final
                                     //time it will equal 0
                                     
                                     
}
 
/*
 * oneOnAtATime() - Will light one LED then the next turning off all the others
 */
void oneOnAtATime(){
  int delayTime = 100; //the time (in milliseconds) to pause between LEDs
                       //make smaller for quicker switching and larger for slower
  
  for(int i = 0; i <= 7; i++){
    int offLED = i - 1;  //Calculate which LED was turned on last time through
    if(i == 0) {         //for i = 1 to 7 this is i minus 1 (i.e. if i = 2 we will
      offLED = 7;        //turn on LED 2 and off LED 1)
    }                    //however if i = 0 we don't want to turn of led -1 (doesn't exist)
                         //instead we turn off LED 7, (looping around)
    digitalWrite(ledPins[i], HIGH);     //turn on LED #i
    digitalWrite(ledPins[offLED], LOW); //turn off the LED we turned on last time
    delay(delayTime);
  }
}
 
/*
 * inAndOut() - This will turn on the two middle LEDs then the next two out
 * making an in and out look
 */
void inAndOut(){
  int delayTime = 100; //the time (in milliseconds) to pause between LEDs
                       //make smaller for quicker switching and larger for slower
  
  //runs the LEDs out from the middle
  for(int i = 0; i <= 3; i++){
    int offLED = i - 1;  //Calculate which LED was turned on last time through
    if(i == 0) {         //for i = 1 to 7 this is i minus 1 (i.e. if i = 2 we will
      offLED = 3;        //turn on LED 2 and off LED 1)
    }                    //however if i = 0 we don't want to turn of led -1 (doesn't exist)
                         //instead we turn off LED 7, (looping around)
    int onLED1 = 3 - i;       //this is the first LED to go on ie. LED #3 when i = 0 and LED 
                             //#0 when i = 3 
    int onLED2 = 4 + i;       //this is the first LED to go on ie. LED #4 when i = 0 and LED 
                             //#7 when i = 3 
    int offLED1 = 3 - offLED; //turns off the LED we turned on last time
    int offLED2 = 4 + offLED; //turns off the LED we turned on last time
    
    digitalWrite(ledPins[onLED1], HIGH);
    digitalWrite(ledPins[onLED2], HIGH);    
    digitalWrite(ledPins[offLED1], LOW);    
    digitalWrite(ledPins[offLED2], LOW);        
    delay(delayTime);
  }
 
  //runs the LEDs into the middle
  for(int i = 3; i >= 0; i--){
    int offLED = i + 1;  //Calculate which LED was turned on last time through
    if(i == 3) {         //for i = 1 to 7 this is i minus 1 (i.e. if i = 2 we will
      offLED = 0;        //turn on LED 2 and off LED 1)
    }                    //however if i = 0 we don't want to turn of led -1 (doesn't exist)
                         //instead we turn off LED 7, (looping around)
    int onLED1 = 3 - i;       //this is the first LED to go on ie. LED #3 when i = 0 and LED 
                             //#0 when i = 3 
    int onLED2 = 4 + i;       //this is the first LED to go on ie. LED #4 when i = 0 and LED 
                             //#7 when i = 3 
    int offLED1 = 3 - offLED; //turns off the LED we turned on last time
    int offLED2 = 4 + offLED; //turns off the LED we turned on last time
    
    digitalWrite(ledPins[onLED1], HIGH);
    digitalWrite(ledPins[onLED2], HIGH);    
    digitalWrite(ledPins[offLED1], LOW);    
    digitalWrite(ledPins[offLED2], LOW);        
    delay(delayTime);
  }
}

Compile and Upload

Before uploading, an important step is to verify that your code compiles. Click on the check button on the toolbar (or, on your keyboard press control+r or command+r for mac users) to compile your code. 

If you receive no errors compiling, upload the sketch to the board (click here for a refresher on how to do this from the previous circuit). After uploading, you should see an animated LED light show like this.

Not Working? CIRC02 not matching the GIF?

Some LEDs Fail to Light

It is easy to insert an LED backwards. Check the LEDs that aren't working and ensure they the right way around.

Operating out of sequence

With eight wires it's easy to cross a couple. Double check that the first LED is plugged into pin 2 and each pin thereafter. 

Not working? Try again with a fresh slate!

Its easy to accidentally misplace a wire without noticing. Pulling everything out and starting with a fresh slate is often easier than trying to track down the problem.

This guide was first published on Aug 18, 2017. It was last updated on Aug 18, 2017.

This page (Code) was last updated on Nov 07, 2020.