portable rainbow (digispark + light_ws2812)

portable-rainbow-digispark-light-ws2812

// Dependency:
//   light_ws2812
//   https://github.com/cpldcpu/light_ws2812
// ---

// if you have USB 3.0 ports, you might need a USB 2.0 hub to program this.

// use the cRGB struct hsv method
#define USE_HSV

#include <WS2812.h>

#define NUM_LEDS 25
#define outputPin 0
#define UPDATES_PER_SECOND 20

WS2812 LED(NUM_LEDS); 
cRGB my_crgb;

int h = 0;   //stores 0 to 614
int x = 2;
byte steps = 1; //number of hues we skip in a 360 range per update

byte sat = 255;
byte val = 220;
  
void setup() {
  // Power up safety delay
  delay(1000);

  LED.setOutput(outputPin);
}

void loop() {
  int inner_h = h;
  for( int i = 0; i < NUM_LEDS; i++ ) {
    if (i%2) {
      inner_h += (i/2)*x;
    }
    if(inner_h >= 360)
    {
        inner_h %= 360;
    }
    my_crgb.SetHSV(inner_h, sat, val);
    LED.set_crgb_at(i, my_crgb);
  }
  h += steps;
  if(h >= 360)
  {
     h %= 360;
  }
  LED.sync();
  delay(1000 / UPDATES_PER_SECOND);
}