Audio FX board:

First we need to transfer sound files to the Audio FX board, following this guide. The sound files I used are included in a zip file. You can find/ make your own sound effects and add them to the Audio FX board, just make sure you follow the proper format outlined here. This project controls the Audio FX board over serial, so the naming conventions aren't as important, and adding new sounds doesn't involve extra wires.


Arduino IDE Set Up:

For interacting with the feather you'll have to have to set up the Arduino IDE to use the Feather. Additionally you'll need to download and install libraries for the 9DOF IMU, Adafruit Sensor, NeoPixels, Audio FX.


Due to differences in the placement of the IMU, hand placement, and personal preference there is a set of sensor settings defined early in the code. Each of these variables help detect simple parts of the gesture recognition, and are independent. For example FLICKTRIG sets how hard you have to flick your wrist for it to register as a flick action.

 The code only has 4 spells currently, but is designed for expandability. Spells are set of by achieving multiple simple condition triggers. For example a fire blast is a wrist flick while horizontal, but doing a wrist flick vertically will summon lightning. Currently there are 3 orientation states, and it can detect flicks and wrist twist. But adding something like a push forward action would allow 3 extra spells with only a few lines of code.

 The code includes some useful settings to help debug, first by setting HARDWARETEST to true the wand will play music and test the NeoPixels in start up. Additionally there is PRINTDATA that prints out the sensor data to help calibrate and come up with new actions.

The startup loop mainly connects to all the different components and if HARDWARETEST is defined as 1, then it also test the sensors, NeoPixels, and the Audio FX board.

The Sensor settings control the sensitivity of when the wand cast spells.

HARDWARETEST and PRINTDATA can be defined as 1 to help with debugging

The other variables set pins for various components and define global variables.

//Written by Alex Alves for Adafruit Industries.
//Adafruit invests time and resources providing this open source code,
//please support Adafruit and open-source hardware by purchasing products
//from Adafruit!
//BSD license, all text above must be included in any redistribution.

#include <SoftwareSerial.h>
#include "Adafruit_Soundboard.h"
#include <Adafruit_NeoPixel.h>
#include <Wire.h>
#include <SPI.h>
#include <Adafruit_LSM9DS0.h>
#include <Adafruit_Sensor.h>  // not used in this demo but required!

#define HARDWARETEST 0 // set to 1 to play sound and test neopixles at start up
#define PRINTDATA 0   // prints out sensor data

////////////    SENSOR SETTINGS     ////////////////////
// these settings may have to be changed and calibrated
// orinetation 
#define VERTICALVAL 11000  // decrease for more senstive
#define HORIZVAL 6000     //  increase for more senstive 

// flick detection
#define FLICKTRIG 17000 // lower = more senstive

// Wrist twist 
#define WRISTDIFF 13000 // lower = more senstive
#define WRISTGY  25000 // higher = more senstive

// Sound
// Choose any two pins that can be used with SoftwareSerial to RX & TX
#define SFX_TX 11
#define SFX_RX 10

// Connect to the RST pin on the Sound Board
#define SFX_RST 18
#define SFX_ACT 23

// we'll be using software serial
SoftwareSerial ss = SoftwareSerial(SFX_TX, SFX_RX);
Adafruit_Soundboard sfx = Adafruit_Soundboard(&ss, NULL, SFX_RST);

// NeoPixels
#define PIXELPIN 9
#define NUM_LEDS 7
#define BRIGHTNESS 255 // max 255
Adafruit_NeoPixel strip = Adafruit_NeoPixel(NUM_LEDS, PIXELPIN, NEO_GRBW + NEO_KHZ800);

// IMU
Adafruit_LSM9DS0 lsm = Adafruit_LSM9DS0();

enum orientation {
// Global state variables
bool wristTwist = false;
bool flick = false;
orientation orient = horiz;

// setup

void setup() {
  pinMode(SFX_ACT, INPUT);

  // softwareserial at 9600 baud
  // can also do Serial1.begin(9600)

  while (!sfx.reset()) {
    Serial.println("Sound Board not found");
    if (! sfx.playTrack("BLAST01 WAV") ) {
      Serial.println("Failed to play track1");


Most of the heavy lifting occurs in reciveData1() which is called every 10ms. When this is called the feather samples and the data from the IMU and detects simple triggers such as writs flicks where meet.


void reciveData1()
  static long int accelCombineL = 0;
  static int accelZL = 0;
  static long int gyroCombineL = 0;
  static int gyroZL = 0;;
  // combine data from x and y axis to make it more simple
  long int accelCombine = sqrt( (sq((long int)lsm.accelData.x) + sq((long int)lsm.accelData.y)));
  int accelZ = (int)lsm.accelData.z;

  long int gyroCombine = sqrt( (sq((long int)lsm.gyroData.x) + sq((long int)lsm.gyroData.y)));
  int gyroZ = (int)lsm.gyroData.z;

  // Numerical differentiante
  int accelCombineDiff = abs((accelCombine - accelCombineL));
  int accelZDiff = abs((accelZ - accelZL));
  int gyroCombineDiff = abs((gyroCombine - gyroCombineL));
  int gyroZDiff = abs((gyroZ - gyroZL));

  int magz = lsm.magData.z;

  //Transfer to static variables for next time
  accelCombineL = accelCombine;
  accelZL = accelZ;
  gyroCombineL = gyroCombine;
  gyroZL = gyroZ;

  if (PRINTDATA) {
        Serial.print(accelCombine); Serial.print(',');
        Serial.print(accelCombineDiff); Serial.print(',');
        Serial.print(accelZ); Serial.print(',');
        Serial.print(accelZDiff); Serial.print(',');
        Serial.print(gyroCombine);      Serial.print(',');
        Serial.print(gyroCombineDiff); Serial.print(',');

        Serial.print(gyroZ);        Serial.print(',');
        Serial.print(gyroZDiff);    Serial.print(',');

        Serial.print(magz);       Serial.println(' ');

  // orientation detection
  if (magz < -VERTICALVAL) {
    orient = vertical;

  else if (magz > -HORIZVAL) {
    orient = horiz;
  else {
    orient = mid;

  // wrist twist detection
  if ((gyroZDiff > WRISTDIFF ) && (abs(gyroZ) > WRISTGY)) {
    wristTwist = true;
  else {
    wristTwist = false;

  // Flick detection
  if ((gyroCombineDiff > FLICKTRIG)) { // (gyroCombine > 16000) &&
    flick = true;
  else {
    flick = false;

The main loop decides where reciveData1() needs to be sampled and then also matches the conditions set from reciveData1() to spells. Once a spell is selected it sets the light and sound effects. No new spells can be cast until the audio of the previous spell has finished.

void loop() {
  static bool spellCasting = false;
  static long unsigned int sampleTrig = 0; // trig for when to sample sensors

  // Take new sample
  if (millis() > sampleTrig) {
    sampleTrig = millis() + 10;

  // conect basic actions together to make difrent spells
  if (!spellCasting) {
    // trigger spell 1
    if (wristTwist && (orient == vertical) ) {
      spellCasting = true;
      sfx.playTrack("LIGHT01 WAV");
      setColor(strip.Color(255, 255, 255, 255));

    else if (wristTwist && (orient == horiz) ) {
      spellCasting = true;
      sfx.playTrack("WIND01  WAV");  //temp
      setColor(strip.Color(150, 255, 100));;

    else if (flick && (orient == horiz)) {
      spellCasting = true;
      sfx.playTrack("FIRE01  WAV");
      setColor(strip.Color(255, 50, 20));

    else if (flick && (orient == vertical)) {
      spellCasting = true;
      setColor(strip.Color(0, 0, 255, 100));

  // spell is being cast
  else {
    // spell just finished
    if (!sfxActive()) {
      spellCasting = false;
      setColor(strip.Color(0, 0, 0));


There are also various helper functions that help set up the individual sensors, interface with the Audio FX board and control the NeoPixels.  Much of the helpfull debug functions are also here.

/************************ MENU HELPERS ***************************/

// Is a sound playing
bool sfxActive() {
  return (! digitalRead(SFX_ACT));

// block wait till sound is finished
void waitSFXFinish() {
  while (sfxActive()) {

/************************ MENU HELPERS ***************************/

// set colors in sequence
void colorWipe(uint32_t c, uint8_t wait) {
  for (uint16_t i = 0; i < strip.numPixels(); i++) {
    strip.setPixelColor(i, c);;

// set all of pixles to one color
void setColor(uint32_t c) {
  for (uint16_t i = 0; i < strip.numPixels(); i++) {
    strip.setPixelColor(i, c);

// set intial pixles status and set brightness
void setupNeoPixel() {
  strip.begin();; // Initialize all pixels to 'off'

    Serial.println("Testing NeoPixels");
    colorWipe(strip.Color(255, 0, 0), 50); // Red
    colorWipe(strip.Color(0, 255, 0), 50); // Green
    colorWipe(strip.Color(0, 0, 255), 50); // Blue
    colorWipe(strip.Color(0, 0, 0, 255), 50); // White
    setColor(strip.Color(0, 0, 0));

/********************** LSM9DSO ********************************/

void setupSensor()
  // 1.) Set the accelerometer range

  // 2.) Set the magnetometer sensitivity

  // 3.) Setup the gyroscope

void connectSensor()
  Serial.println("Connecting to Sensor");

  // Try to initialise and warn if we couldn't detect the chip
  while (!lsm.begin())
    Serial.println("Oops ... unable to initialize the LSM9DS0. Trying again");
  Serial.println("Found LSM9DS0 9DOF");

This guide was first published on Mar 28, 2017. It was last updated on Mar 28, 2017.

This page (Software) was last updated on Feb 27, 2017.

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