Load up this animation to your Pro Trinket! You'll need the NeoPixel library if you don't have it already.
#include <Adafruit_NeoPixel.h>
#define PIN 4
Adafruit_NeoPixel strip = Adafruit_NeoPixel(58, PIN, NEO_GRB + NEO_KHZ800);
int snakeLength=10; // How long of trails do you want?
int frameDelay = 30; // Lower numbers = faster animation
int waveDirection = 0; // 0 = right, 1 = left
int rgb[3] = {255,0,0}; // Color for the main pixel
int trailingRGB[3] = {0,0,0}; // Color for the trailing pixels
int hue = 60; // We're going to start off with red
int currentLED = 0; // Current LED.
int trailingLED = 0; // LED that is trailing the current LED
uint16_t i, j;
void setup() {
strip.begin();
strip.show(); // Initialize all pixels to 'off'
}
void loop() {
if (currentLED > 0 && currentLED <= strip.numPixels()) {
strip.setPixelColor(currentLED, rgb[0], rgb[1], rgb[2]);
}
if (waveDirection == 0) { // Wave travelling right
for (j = 0; j < snakeLength; j++) {
trailingLED = currentLED - j;
if (trailingLED > 0) {
hsi2rgb(hue,1,1/(j+0.1),trailingRGB);
if(trailingLED > 0 && trailingLED <=strip.numPixels()) {
strip.setPixelColor(trailingLED, trailingRGB[0], trailingRGB[1], trailingRGB[2]);
}
}
}
trailingLED--;
if(trailingLED > 0) {
strip.setPixelColor(trailingLED,0,0,0);
}
} else { // Wave travelling left
for (j = 0; j < snakeLength; j++) {
trailingLED = currentLED + j;
if (trailingLED < strip.numPixels()) {
hsi2rgb(hue,1,1/(j+0.1),trailingRGB);
if(trailingLED > 0 && trailingLED <=strip.numPixels()) {
strip.setPixelColor(trailingLED, trailingRGB[0], trailingRGB[1], trailingRGB[2]);
}
}
}
trailingLED++;
if(trailingLED < strip.numPixels()) {
strip.setPixelColor(trailingLED,0,0,0);
}
}
strip.show();
if (waveDirection == 0) {
currentLED++;
} else {
currentLED--;
}
if (currentLED > strip.numPixels()) {
waveDirection = 1;
currentLED-=2;
}
if (currentLED < 0) {
waveDirection = 0;
currentLED+=2;
}
hue+=4;
if(hue > 360) {
hue = 0;
}
delay(frameDelay);
}
// (FUNCTION STOLEN FROM http://blog.saikoled.com/post/43693602826/why-every-led-light-should-be-using-hsi-colorspace on 10/27/14)
// This function will make it easier to create lighter and darker versions of the same color.
//
// Function example takes H, S, I, and a pointer to the
// returned RGB colorspace converted vector. It should
// be initialized with:
//
// int rgb[3];
//
// in the calling function. After calling hsi2rgb
// the vector rgb will contain red, green, and blue
// calculated values.
void hsi2rgb(float H, float S, float I, int* rgb) {
int r, g, b;
H = fmod(H,360); // cycle H around to 0-360 degrees
H = 3.14159*H/(float)180; // Convert to radians.
S = S>0?(S<1?S:1):0; // clamp S and I to interval [0,1]
I = I>0?(I<1?I:1):0;
// Math! Thanks in part to Kyle Miller.
if(H < 2.09439) {
r = 255*I/3*(1+S*cos(H)/cos(1.047196667-H));
g = 255*I/3*(1+S*(1-cos(H)/cos(1.047196667-H)));
b = 255*I/3*(1-S);
} else if(H < 4.188787) {
H = H - 2.09439;
g = 255*I/3*(1+S*cos(H)/cos(1.047196667-H));
b = 255*I/3*(1+S*(1-cos(H)/cos(1.047196667-H)));
r = 255*I/3*(1-S);
} else {
H = H - 4.188787;
b = 255*I/3*(1+S*cos(H)/cos(1.047196667-H));
r = 255*I/3*(1+S*(1-cos(H)/cos(1.047196667-H)));
g = 255*I/3*(1-S);
}
rgb[0]=r;
rgb[1]=g;
rgb[2]=b;
}
