The Arduino code presented below works equally well on GEMMA: v2 and M0. But if you have an M0 board, consider using the CircuitPython code on the next page of this guide, no Arduino IDE required!
To program GEMMA, make sure you have followed the instructions found in the "Introducing GEMMA" guide.
Once you've got the GEMMA working, you can play with different example sketches, or code your own blinky pattern.
If you'd like an exciting, fiery pattern to run, download and install the FastLED Arduino library found here, and then copy the following Arduino sketch.
Plug the GEMMA into a USB cable connected to your computer, press and release the reset button on the GEMMA (the red LED on the GEMMA will blink) and then use the Arduino software IDE to upload the sketch to the board.
// SPDX-FileCopyrightText: 2018 Mikey Sklar for Adafruit Industries
//
// SPDX-License-Identifier: MIT
#include <FastLED.h>
#define LED_PIN 0
#define COLOR_ORDER GRB
#define CHIPSET WS2811
#define NUM_LEDS 30
#define BRIGHTNESS 200
#define FRAMES_PER_SECOND 60
bool gReverseDirection = false;
CRGB leds[NUM_LEDS];
void setup() {
delay(3000); // sanity delay
FastLED.addLeds<CHIPSET, LED_PIN, COLOR_ORDER>(leds, NUM_LEDS).setCorrection( TypicalLEDStrip );
FastLED.setBrightness( BRIGHTNESS );
}
void loop()
{
// Add entropy to random number generator; we use a lot of it.
// random16_add_entropy( random());
Fire2012(); // run simulation frame
FastLED.show(); // display this frame
FastLED.delay(1000 / FRAMES_PER_SECOND);
}
// Fire2012 by Mark Kriegsman, July 2012
// as part of "Five Elements" shown here: http://youtu.be/knWiGsmgycY
////
// This basic one-dimensional 'fire' simulation works roughly as follows:
// There's a underlying array of 'heat' cells, that model the temperature
// at each point along the line. Every cycle through the simulation,
// four steps are performed:
// 1) All cells cool down a little bit, losing heat to the air
// 2) The heat from each cell drifts 'up' and diffuses a little
// 3) Sometimes randomly new 'sparks' of heat are added at the bottom
// 4) The heat from each cell is rendered as a color into the leds array
// The heat-to-color mapping uses a black-body radiation approximation.
//
// Temperature is in arbitrary units from 0 (cold black) to 255 (white hot).
//
// This simulation scales it self a bit depending on NUM_LEDS; it should look
// "OK" on anywhere from 20 to 100 LEDs without too much tweaking.
//
// I recommend running this simulation at anywhere from 30-100 frames per second,
// meaning an interframe delay of about 10-35 milliseconds.
//
// Looks best on a high-density LED setup (60+ pixels/meter).
//
//
// There are two main parameters you can play with to control the look and
// feel of your fire: COOLING (used in step 1 above), and SPARKING (used
// in step 3 above).
//
// COOLING: How much does the air cool as it rises?
// Less cooling = taller flames. More cooling = shorter flames.
// Default 50, suggested range 20-100
#define COOLING 55
// SPARKING: What chance (out of 255) is there that a new spark will be lit?
// Higher chance = more roaring fire. Lower chance = more flickery fire.
// Default 120, suggested range 50-200.
#define SPARKING 120
void Fire2012()
{
// Array of temperature readings at each simulation cell
static byte heat[NUM_LEDS];
// Step 1. Cool down every cell a little
for( int i = 0; i < NUM_LEDS; i++) {
heat[i] = qsub8( heat[i], random8(0, ((COOLING * 10) / NUM_LEDS) + 2));
}
// Step 2. Heat from each cell drifts 'up' and diffuses a little
for( int k= NUM_LEDS - 1; k >= 2; k--) {
heat[k] = (heat[k - 1] + heat[k - 2] + heat[k - 2] ) / 3;
}
// Step 3. Randomly ignite new 'sparks' of heat near the bottom
if( random8() < SPARKING ) {
int y = random8(7);
heat[y] = qadd8( heat[y], random8(160,255) );
}
// Step 4. Map from heat cells to LED colors
for( int j = 0; j < NUM_LEDS; j++) {
CRGB color = HeatColor( heat[j]);
int pixelnumber;
if( gReverseDirection ) {
pixelnumber = (NUM_LEDS-1) - j;
} else {
pixelnumber = j;
}
leds[pixelnumber] = color;
}
}
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