The code presented on this page can be downloaded or found in the Arduino examples menu under Examples → SpinWearables → Animations_and_Patterns → Railroad_Signal.

An Animation Resembling a Railroad Signal

In our animations and patterns lesson we describe how an animation can be created by instructing a computer to make a particular drawing dependent on a single number, the current time. This is a small example doing exactly that: We read the current time, divide it in intervals, and depending on the time since the start of the last interval, we change the brightness of two LEDs, forcing them into opposing colors. Some pieces of code are the same as in previous examples from this series on coded animations, We do not comment them as extensively here, but consult the Simple_Blink example if you need a refresher.

#include "SpinWearables.h"
using namespace SpinWearables;

void setup() {

void loop() {
  int t = millis();
  int t_repeat = t % 2500;

Here we use a function that turns the steadily increasing and then abruptly dropping t_repeat into a neater rising and falling pattern.

  int w = triangularWave(t_repeat/10);

We also want a number that is the exact opposite of w. Something that is large and bright when w is small and that is also small when w is large.

  int w_opposite = 255 - w;

Set LED number 0 to a red color with an intensity governed by w

  SpinWheel.setLargeLED(0, w, 0, 0);

Set LED number 2 to a red color with an intensity governed by w_opposite

  SpinWheel.setLargeLED(2, 0, w_opposite, 0);

Draw the image that was prepared in the previous lines.