• How to write the status of a single LED
• How to perform bitwise operations to achieve correct color codes
• How to create simple functions
• How to create a pattern for a light show

You can copy / paste the code below if you’re having issues with typos or want a shortcut. However I recommend that you follow along in the tutorial to understand what is going on!

simpleon.ino

#include <Adafruit_DotStar.h>
#include <SPI.h>

#define NUMPIXELS 30

// Create the strip

Adafruit_DotStar strip = Adafruit_DotStar(NUMPIXELS, DOTSTAR_BRG) ;

void simpleOn(uint32_t color, uint8_t head, uint8_t tail) {
  for (int i=(tail-1); i < head; i++){
    strip.setPixelColor(i, color) ;
  }
  strip.show() ;
}

void setup() {
  strip.begin() ;
  strip.show() ; // This turns off the LEDs within NUMPIXELS

}

void loop() {
  uint8_t head, tail ;
  uint32_t color ;
  color = 0x1577D5 ;
  head = 7 ;
  tail = 2 ;
  simpleOn(color, head, tail) ;
  delay(1000) ;

}
//>

lightbounce.ino

#include <SPI.h>
#include <Adafruit_DotStar.h>

#define NUMPIXELS 30

Adafruit_DotStar strip = Adafruit_DotStar(NUMPIXELS, DOTSTAR_BRG) ;

void bounceBetween(uint32_t color, uint16_t start, uint16_t finish, uint16_t len){

  int path_length = finish-start ;
  
  // Get light snake moving forward down the line.
  for (int i=0 ; i < path_length ; i++){
    // Populate the snake
    for (int j=0 ; j < len ; j++){
      if ((j+i+start) <= finish){
        strip.setPixelColor(i+j+start, color) ;
        strip.show() ;
      }
    }
    // Write the end of the snake to be "off"
    if ( (i+start) <= (finish-len) ){
      strip.setPixelColor(i+start, 0) ;
      delay(50) ;
    }
  }

  // Get the light snake moving backwards.
  for (int i=0 ; (-1)*i < path_length ; i--){
    // Populate the snake
    for (int j=0 ; (-1)*j < len ; j--){
      if ((i+j+finish) >= start){
        strip.setPixelColor(i+j+finish, color) ;
        strip.show() ;  
      }
    }
    // Write the end of the snake to be "off"
    if ( (i+finish) >= (len+start) ){
      strip.setPixelColor(i+finish, 0) ;
      delay(50) ;
    }
  }
}

uint32_t randColor(){
  uint8_t red = random(0,255) ;
  uint8_t blue = random(0,255) ;
  uint8_t green = random(0,255) ;

  uint32_t color = 0x000000 ; //GRB

  color = color | (green << 16) ;
  color = color | (red << 8) ;
  color = color | blue ;

  return color ;
}

void setup() {
  strip.begin() ;
  strip.show() ;
}

void loop() {
  uint32_t color = randColor() ;
  bounceBetween(color, 2, 12, 4) ;
}
//>