The Code
The Gemma is programmed via USB with the Arduino IDE. You can modify and customize the code to fit your setup. For starters, we can easy change the pin outs and number of NeoPixels. In our setup, our tree topper used 36 NeoPixels.
If your new to using the Gemma and the Arduino IDE, check out this guide for the original Gemma or this guide for the Gemma M0 for setting up. Have some extra time on your hands? Learn how to customize the code to change the animation sequence!
We slightly modified another project’s code to use a single purple color, but you can change it to whatever you like! Look for this line where a hexadecimal color value is listed (around line 10):
uint32_t color = 0xA000A0;
Just replace "#A000A0" with whatever hex color value you want, it's that easy!
// SPDX-FileCopyrightText: 2017 Phillip Burgess for Adafruit Industries
//
// SPDX-License-Identifier: MIT
#include <Adafruit_NeoPixel.h>
#define PIN 1
#define NUM_LEDS 36
Adafruit_NeoPixel pixels = Adafruit_NeoPixel(NUM_LEDS, PIN);
uint8_t mode = 0, // Current animation effect
offset = 0; // Position of spinner animation
uint32_t color = 0xA000A0; // Purple
uint32_t prevTime; // Time of last animation mode switch
void setup() {
pixels.begin();
pixels.setBrightness(255); // Full brightness
prevTime = millis(); // Starting time
}
void loop() {
uint8_t i;
uint32_t t;
switch(mode) {
case 0: // Random sparkles - just one LED on at a time!
i = random(NUM_LEDS); // Choose a random pixel
pixels.setPixelColor(i, color); // Set it to current color
pixels.show(); // Refresh LED states
// Set same pixel to "off" color now but DON'T refresh...
// it stays on for now...both this and the next random
// pixel will be refreshed on the next pass.
pixels.setPixelColor(i, 0);
delay(10); // 10 millisecond delay
break;
case 1: // Spinny wheel
for(i=0; i<NUM_LEDS; i++) { // For each LED...
uint32_t c = 0; // Assume pixel will be "off" color
if(((offset + i) & 7) < 2) { // For each 8 pixels, 2 will be...
c = color; // ...assigned the current color
}
pixels.setPixelColor(i, c); // Set color of pixel 'i'
}
pixels.show(); // Refresh LED states
delay(90); // 90 millisecond delay
offset++; // Shift animation by 1 pixel on next frame
break;
// More animation modes could be added here!
}
t = millis(); // Current time in milliseconds
if((t - prevTime) > 8000) { // Every 8 seconds...
mode++; // Advance to next animation mode
if(mode > 1) { // End of modes?
mode = 0; // Start over from beginning
}
pixels.clear(); // Set all pixels to 'off' state
prevTime = t; // Record the time of the last mode change
}
}
Page last edited January 21, 2025
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