Hello,
I am trying to build a head tracker using a Teensy 2.0 and the LSM9DS0 IMU Breakout by adafruit. I connected the following:
Teensy 2.0 -- IMU
D0 --> SCL
D1 --> SDA
GND --> GND
VCC --> VDD
I compiled the following code and uploaded it, rebooted the device. I run joy.cpl and see the Teensy 2.0 which is emulating a joystick/keyboard/mouse, but when I go to properties to test moving the head tracker doesn't move the mouse cursor at all. Am I missing something? Here is the code that I have running as well. Any help is greatly appreciated. This is all based on this blog post: http://planetkris.com/2014/12/easier-better-arduino-imu-head-tracker/
/*
Based on the Madgwick algorithm found at:
See: http://www.x-io.co.uk/open-source-imu-and-ahrs-algorithms/
This code inherits all relevant liscenses and may be freely modified and redistributed.
The MinIMU v1 has a roughly +/- 10degree accuracy
The MinIMU v2 has a roughly +/- 1 degree accuracy
*/
#include <LSM303.h>
#include <L3G.h>
#include <Wire.h>
#define ToRad(x) ((x) * 0.01745329252) // *pi/180
#define ToDeg(x) ((x) * 57.2957795131) // *180/pi
#define PI_FLOAT 3.14159265f
#define PIBY2_FLOAT 1.5707963f
#define GYRO_SCALE 0.07f
#define betaDef 0.08f
//To find the calibration values us the sketch included with the LSM303 driver from pololu
/*Change line 11 from
compass.enableDefault();
to
compass.writeMagReg(LSM303_CRA_REG_M, 0x1C);
compass.writeMagReg(LSM303_CRB_REG_M, 0x60);
compass.writeMagReg(LSM303_MR_REG_M, 0x00);
Then put the calibration values below
*/
#define compassXMin -283.0f
#define compassYMin -186.0f
#define compassZMin -198.0f
#define compassXMax 395.0f
#define compassYMax 488.0f
#define compassZMax 413.0f
#define inverseXRange (float)(2.0 / (compassXMax - compassXMin))
#define inverseYRange (float)(2.0 / (compassYMax - compassYMin))
#define inverseZRange (float)(2.0 / (compassZMax - compassZMin))
#define headingtimeout 20000 //20 sec in ms
// Teensy 2.0 has the LED on pin 11
// Teensy++ 2.0 has the LED on pin 6
// Teensy 3.0 has the LED on pin 13
const int ledPin = 11;
L3G gyro;
LSM303 compass;
long timer, printTimer;
float G_Dt;
int loopCount;
int blinkCount;
float q0;
float q1;
float q2;
float q3;
float beta;
float magnitude;
float pitch,roll,yaw;
float gyroSumX,gyroSumY,gyroSumZ;
float offSetX,offSetY,offSetZ;
float floatMagX,floatMagY,floatMagZ;
float smoothAccX,smoothAccY,smoothAccZ;
float accToFilterX,accToFilterY,accToFilterZ;
int i;
int inithead; //Store initial heading
boolean fixed; //Lock in that heading
int newhead; //360 degree transformation
void setup(){
//Serial.begin(115200);
//Serial.println("Keeping the device still and level during startup will yeild the best results");
pinMode(ledPin, OUTPUT);
digitalWrite(ledPin, HIGH); // set the LED on
delay(100);
Wire.begin();
TWBR = ((F_CPU / 400000) - 16) / 2;//set the I2C speed to 400KHz
IMUinit();
printTimer = millis();
timer = micros();
blinkCount = 0;
inithead = yaw; // Grab an initial heading - expect this to change
fixed = false;
}
void loop(){
if (micros() - timer >= 5000){
//this runs in 4ms on the MEGA 2560
G_Dt = (micros() - timer)/1000000.0;
timer=micros();
compass.read();
floatMagX = ((float)compass.m.x - compassXMin) * inverseXRange - 1.0;
floatMagY = ((float)compass.m.y - compassYMin) * inverseYRange - 1.0;
floatMagZ = ((float)compass.m.z - compassZMin) * inverseZRange - 1.0;
Smoothing(&compass.a.x,&smoothAccX);
Smoothing(&compass.a.y,&smoothAccY);
Smoothing(&compass.a.z,&smoothAccZ);
accToFilterX = smoothAccX;
accToFilterY = smoothAccY;
accToFilterZ = smoothAccZ;
gyro.read();
AHRSupdate(&G_Dt);
//update the joystick heading coordinates
// modify degress for heading
newhead = yaw-inithead;
if(newhead > 180){newhead = -360+newhead;}
else if(newhead < -180){newhead = 360+newhead;}
if (newhead < 0){newhead = fscale(-40, 0, 0, 512, newhead,0);}
else {newhead = fscale(0, 40, 512, 1023, newhead,0);}
if (newhead < 0){newhead = 0;}
if (newhead > 1023){newhead = 1023;}
Joystick.Z(newhead);
}
if (millis() - printTimer > 10){
printTimer = millis();
GetEuler();
//Serial.print("!ANG:"); //This is what MinIMU-9-test.py is looking for
//Serial.print(roll);
if (roll < 0){roll = fscale(-25, 0, 0, 512, roll,0);}
else {roll = fscale(0, 25, 512, 1023, roll,0);}
if (roll < 0){roll = 0;}
if (roll > 1023){roll = 1023;}
Joystick.X(roll);
//Serial.print(",");
//Serial.print(pitch);
if (pitch < 0){pitch = fscale(-25, 0, 0, 512, pitch,0);}
else {pitch = fscale(0, 25, 512, 1023, pitch,0);}
if (pitch < 0){pitch = 0;}
if (pitch > 1023){pitch = 1023;}
Joystick.Y(pitch);
//Serial.print(",");
//Serial.println(yaw);
//DEBUG STUFF
//Serial.println(printTimer);
//Serial.print(smoothedYaw);
//Serial.print(", ");
//Serial.println(roll);
if (fixed == false){
blinkCount++;
if (blinkCount > 15) {digitalWrite(ledPin, HIGH);}
if (blinkCount > 30) {digitalWrite(ledPin, LOW); blinkCount=0;}
if (printTimer > headingtimeout) {inithead = yaw;
fixed = true;
digitalWrite(ledPin, HIGH); // set the LED on
}
}
}
}
void IMUinit(){
//init devices
compass.init();
gyro.init();
gyro.writeReg(L3G_CTRL_REG1, 0xCF);
gyro.writeReg(L3G_CTRL_REG2, 0x00);
gyro.writeReg(L3G_CTRL_REG3, 0x00);
gyro.writeReg(L3G_CTRL_REG4, 0x20); //
gyro.writeReg(L3G_CTRL_REG5, 0x02);
compass.writeAccReg(LSM303_CTRL_REG1_A, 0x77);//400hz all enabled
compass.writeAccReg(LSM303_CTRL_REG4_A, 0x20);//+/-8g 4mg/LSB
compass.writeMagReg(LSM303_CRA_REG_M, 0x1C);
compass.writeMagReg(LSM303_CRB_REG_M, 0x60);
compass.writeMagReg(LSM303_MR_REG_M, 0x00);
beta = betaDef;
//calculate initial quaternion
//take an average of the gyro readings to remove the bias
for (i = 0; i < 500;i++){
gyro.read();
compass.read();
Smoothing(&compass.a.x,&smoothAccX);
Smoothing(&compass.a.y,&smoothAccY);
Smoothing(&compass.a.z,&smoothAccZ);
delay(3);
}
gyroSumX = 0;
gyroSumY = 0;
gyroSumZ = 0;
for (i = 0; i < 500;i++){
gyro.read();
compass.read();
Smoothing(&compass.a.x,&smoothAccX);
Smoothing(&compass.a.y,&smoothAccY);
Smoothing(&compass.a.z,&smoothAccZ);
gyroSumX += (gyro.g.x);
gyroSumY += (gyro.g.y);
gyroSumZ += (gyro.g.z);
delay(3);
}
offSetX = gyroSumX / 500.0;
offSetY = gyroSumY / 500.0;
offSetZ = gyroSumZ / 500.0;
compass.read();
//calculate the initial quaternion
//these are rough values. This calibration works a lot better if the device is kept as flat as possible
//find the initial pitch and roll
pitch = ToDeg(fastAtan2(compass.a.x,sqrt(compass.a.y * compass.a.y + compass.a.z * compass.a.z)));
roll = ToDeg(fastAtan2(-1*compass.a.y,sqrt(compass.a.x * compass.a.x + compass.a.z * compass.a.z)));
if (compass.a.z > 0){
if (compass.a.x > 0){
pitch = 180.0 - pitch;
}
else{
pitch = -180.0 - pitch;
}
if (compass.a.y > 0){
roll = -180.0 - roll;
}
else{
roll = 180.0 - roll;
}
}
floatMagX = (compass.m.x - compassXMin) * inverseXRange - 1.0;
floatMagY = (compass.m.y - compassYMin) * inverseYRange - 1.0;
floatMagZ = (compass.m.z - compassZMin) * inverseZRange - 1.0;
//tilt compensate the compass
float xMag = (floatMagX * cos(ToRad(pitch))) + (floatMagZ * sin(ToRad(pitch)));
float yMag = -1 * ((floatMagX * sin(ToRad(roll)) * sin(ToRad(pitch))) + (floatMagY * cos(ToRad(roll))) - (floatMagZ * sin(ToRad(roll)) * cos(ToRad(pitch))));
yaw = ToDeg(fastAtan2(yMag,xMag));
if (yaw < 0){
yaw += 360;
}
//Serial.println(roll);
//Serial.println(pitch);
//Serial.println(yaw);
//calculate the rotation matrix
float cosPitch = cos(ToRad(pitch));
float sinPitch = sin(ToRad(pitch));
float cosRoll = cos(ToRad(roll));
float sinRoll = sin(ToRad(roll));
float cosYaw = cos(ToRad(yaw));
float sinYaw = sin(ToRad(yaw));
//need the transpose of the rotation matrix
float r11 = cosPitch * cosYaw;
float r21 = cosPitch * sinYaw;
float r31 = -1.0 * sinPitch;
float r12 = -1.0 * (cosRoll * sinYaw) + (sinRoll * sinPitch * cosYaw);
float r22 = (cosRoll * cosYaw) + (sinRoll * sinPitch * sinYaw);
float r32 = sinRoll * cosPitch;
float r13 = (sinRoll * sinYaw) + (cosRoll * sinPitch * cosYaw);
float r23 = -1.0 * (sinRoll * cosYaw) + (cosRoll * sinPitch * sinYaw);
float r33 = cosRoll * cosPitch;
//convert to quaternion
q0 = 0.5 * sqrt(1 + r11 + r22 + r33);
q1 = (r32 - r23)/(4 * q0);
q2 = (r13 - r31)/(4 * q0);
q3 = (r21 - r12)/(4 * q0);
}
void IMUupdate(float *dt) {
static float gx;
static float gy;
static float gz;
static float ax;
static float ay;
static float az;
static float recipNorm;
static float s0, s1, s2, s3;
static float qDot1, qDot2, qDot3, qDot4;
static float _2q0, _2q1, _2q2, _2q3, _4q0, _4q1, _4q2 ,_8q1, _8q2, q0q0, q1q1, q2q2, q3q3;
gx = ToRad((gyro.g.x - offSetX) * GYRO_SCALE);
gy = ToRad((gyro.g.y - offSetY) * GYRO_SCALE);
gz = ToRad((gyro.g.z - offSetZ) * GYRO_SCALE);
ax = -1.0 * compass.a.x;
ay = -1.0 * compass.a.y;
az = -1.0 * compass.a.z;
// Rate of change of quaternion from gyroscope
qDot1 = 0.5f * (-q1 * gx - q2 * gy - q3 * gz);
qDot2 = 0.5f * (q0 * gx + q2 * gz - q3 * gy);
qDot3 = 0.5f * (q0 * gy - q1 * gz + q3 * gx);
qDot4 = 0.5f * (q0 * gz + q1 * gy - q2 * gx);
magnitude = sqrt(ax * ax + ay * ay + az * az);
if ((magnitude > 384) || (magnitude < 128)){
ax = 0;
ay = 0;
az = 0;
}
// Compute feedback only if accelerometer measurement valid (avoids NaN in accelerometer normalisation)
if(!((ax == 0.0f) && (ay == 0.0f) && (az == 0.0f))) {
// Normalise accelerometer measurement
recipNorm = invSqrt(ax * ax + ay * ay + az * az);
ax *= recipNorm;
ay *= recipNorm;
az *= recipNorm;
// Auxiliary variables to avoid repeated arithmetic
_2q0 = 2.0f * q0;
_2q1 = 2.0f * q1;
_2q2 = 2.0f * q2;
_2q3 = 2.0f * q3;
_4q0 = 4.0f * q0;
_4q1 = 4.0f * q1;
_4q2 = 4.0f * q2;
_8q1 = 8.0f * q1;
_8q2 = 8.0f * q2;
q0q0 = q0 * q0;
q1q1 = q1 * q1;
q2q2 = q2 * q2;
q3q3 = q3 * q3;
// Gradient decent algorithm corrective step
s0 = _4q0 * q2q2 + _2q2 * ax + _4q0 * q1q1 - _2q1 * ay;
s1 = _4q1 * q3q3 - _2q3 * ax + 4.0f * q0q0 * q1 - _2q0 * ay - _4q1 + _8q1 * q1q1 + _8q1 * q2q2 + _4q1 * az;
s2 = 4.0f * q0q0 * q2 + _2q0 * ax + _4q2 * q3q3 - _2q3 * ay - _4q2 + _8q2 * q1q1 + _8q2 * q2q2 + _4q2 * az;
s3 = 4.0f * q1q1 * q3 - _2q1 * ax + 4.0f * q2q2 * q3 - _2q2 * ay;
recipNorm = invSqrt(s0 * s0 + s1 * s1 + s2 * s2 + s3 * s3); // normalise step magnitude
s0 *= recipNorm;
s1 *= recipNorm;
s2 *= recipNorm;
s3 *= recipNorm;
// Apply feedback step
qDot1 -= beta * s0;
qDot2 -= beta * s1;
qDot3 -= beta * s2;
qDot4 -= beta * s3;
}
// Integrate rate of change of quaternion to yield quaternion
q0 += qDot1 * *dt;
q1 += qDot2 * *dt;
q2 += qDot3 * *dt;
q3 += qDot4 * *dt;
// Normalise quaternion
recipNorm = invSqrt(q0 * q0 + q1 * q1 + q2 * q2 + q3 * q3);
q0 *= recipNorm;
q1 *= recipNorm;
q2 *= recipNorm;
q3 *= recipNorm;
}
void AHRSupdate(float *dt) {
static float gx;
static float gy;
static float gz;
static float ax;
static float ay;
static float az;
static float mx;
static float my;
static float mz;
static float recipNorm;
static float s0, s1, s2, s3;
static float qDot1, qDot2, qDot3, qDot4;
static float hx, hy;
static float _2q0mx, _2q0my, _2q0mz, _2q1mx, _2bx, _2bz, _4bx, _4bz, _2q0, _2q1, _2q2, _2q3, _2q0q2, _2q2q3, q0q0, q0q1, q0q2, q0q3, q1q1, q1q2, q1q3, q2q2, q2q3, q3q3;
gx = ToRad((gyro.g.x - offSetX) * GYRO_SCALE);
gy = ToRad((gyro.g.y - offSetY) * GYRO_SCALE);
gz = ToRad((gyro.g.z - offSetZ) * GYRO_SCALE);
ax = -1.0 * compass.a.x;
ay = -1.0 * compass.a.y;
az = -1.0 * compass.a.z;
mx = floatMagX;
my = floatMagY;
mz = floatMagZ;
// Rate of change of quaternion from gyroscope
qDot1 = 0.5f * (-q1 * gx - q2 * gy - q3 * gz);
qDot2 = 0.5f * (q0 * gx + q2 * gz - q3 * gy);
qDot3 = 0.5f * (q0 * gy - q1 * gz + q3 * gx);
qDot4 = 0.5f * (q0 * gz + q1 * gy - q2 * gx);
magnitude = sqrt(ax * ax + ay * ay + az * az);
if ((magnitude > 384) || (magnitude < 128)){
ax = 0;
ay = 0;
az = 0;
}
// Compute feedback only if accelerometer measurement valid (avoids NaN in accelerometer normalisation)
if(!((ax == 0.0f) && (ay == 0.0f) && (az == 0.0f))) {
// Normalise accelerometer measurement
recipNorm = invSqrt(ax * ax + ay * ay + az * az);
ax *= recipNorm;
ay *= recipNorm;
az *= recipNorm;
// Normalise magnetometer measurement
recipNorm = invSqrt(mx * mx + my * my + mz * mz);
mx *= recipNorm;
my *= recipNorm;
mz *= recipNorm;
// Auxiliary variables to avoid repeated arithmetic
_2q0mx = 2.0f * q0 * mx;
_2q0my = 2.0f * q0 * my;
_2q0mz = 2.0f * q0 * mz;
_2q1mx = 2.0f * q1 * mx;
_2q0 = 2.0f * q0;
_2q1 = 2.0f * q1;
_2q2 = 2.0f * q2;
_2q3 = 2.0f * q3;
_2q0q2 = 2.0f * q0 * q2;
_2q2q3 = 2.0f * q2 * q3;
q0q0 = q0 * q0;
q0q1 = q0 * q1;
q0q2 = q0 * q2;
q0q3 = q0 * q3;
q1q1 = q1 * q1;
q1q2 = q1 * q2;
q1q3 = q1 * q3;
q2q2 = q2 * q2;
q2q3 = q2 * q3;
q3q3 = q3 * q3;
// Reference direction of Earth's magnetic field
hx = mx * q0q0 - _2q0my * q3 + _2q0mz * q2 + mx * q1q1 + _2q1 * my * q2 + _2q1 * mz * q3 - mx * q2q2 - mx * q3q3;
hy = _2q0mx * q3 + my * q0q0 - _2q0mz * q1 + _2q1mx * q2 - my * q1q1 + my * q2q2 + _2q2 * mz * q3 - my * q3q3;
_2bx = sqrt(hx * hx + hy * hy);
_2bz = -_2q0mx * q2 + _2q0my * q1 + mz * q0q0 + _2q1mx * q3 - mz * q1q1 + _2q2 * my * q3 - mz * q2q2 + mz * q3q3;
_4bx = 2.0f * _2bx;
_4bz = 2.0f * _2bz;
// Gradient decent algorithm corrective step
s0 = -_2q2 * (2.0f * q1q3 - _2q0q2 - ax) + _2q1 * (2.0f * q0q1 + _2q2q3 - ay) - _2bz * q2 * (_2bx * (0.5f - q2q2 - q3q3) + _2bz * (q1q3 - q0q2) - mx) + (-_2bx * q3 + _2bz * q1) * (_2bx * (q1q2 - q0q3) + _2bz * (q0q1 + q2q3) - my) + _2bx * q2 * (_2bx * (q0q2 + q1q3) + _2bz * (0.5f - q1q1 - q2q2) - mz);
s1 = _2q3 * (2.0f * q1q3 - _2q0q2 - ax) + _2q0 * (2.0f * q0q1 + _2q2q3 - ay) - 4.0f * q1 * (1 - 2.0f * q1q1 - 2.0f * q2q2 - az) + _2bz * q3 * (_2bx * (0.5f - q2q2 - q3q3) + _2bz * (q1q3 - q0q2) - mx) + (_2bx * q2 + _2bz * q0) * (_2bx * (q1q2 - q0q3) + _2bz * (q0q1 + q2q3) - my) + (_2bx * q3 - _4bz * q1) * (_2bx * (q0q2 + q1q3) + _2bz * (0.5f - q1q1 - q2q2) - mz);
s2 = -_2q0 * (2.0f * q1q3 - _2q0q2 - ax) + _2q3 * (2.0f * q0q1 + _2q2q3 - ay) - 4.0f * q2 * (1 - 2.0f * q1q1 - 2.0f * q2q2 - az) + (-_4bx * q2 - _2bz * q0) * (_2bx * (0.5f - q2q2 - q3q3) + _2bz * (q1q3 - q0q2) - mx) + (_2bx * q1 + _2bz * q3) * (_2bx * (q1q2 - q0q3) + _2bz * (q0q1 + q2q3) - my) + (_2bx * q0 - _4bz * q2) * (_2bx * (q0q2 + q1q3) + _2bz * (0.5f - q1q1 - q2q2) - mz);
s3 = _2q1 * (2.0f * q1q3 - _2q0q2 - ax) + _2q2 * (2.0f * q0q1 + _2q2q3 - ay) + (-_4bx * q3 + _2bz * q1) * (_2bx * (0.5f - q2q2 - q3q3) + _2bz * (q1q3 - q0q2) - mx) + (-_2bx * q0 + _2bz * q2) * (_2bx * (q1q2 - q0q3) + _2bz * (q0q1 + q2q3) - my) + _2bx * q1 * (_2bx * (q0q2 + q1q3) + _2bz * (0.5f - q1q1 - q2q2) - mz);
recipNorm = invSqrt(s0 * s0 + s1 * s1 + s2 * s2 + s3 * s3); // normalise step magnitude
s0 *= recipNorm;
s1 *= recipNorm;
s2 *= recipNorm;
s3 *= recipNorm;
// Apply feedback step
qDot1 -= beta * s0;
qDot2 -= beta * s1;
qDot3 -= beta * s2;
qDot4 -= beta * s3;
}
// Integrate rate of change of quaternion to yield quaternion
q0 += qDot1 * *dt;
q1 += qDot2 * *dt;
q2 += qDot3 * *dt;
q3 += qDot4 * *dt;
// Normalise quaternion
recipNorm = invSqrt(q0 * q0 + q1 * q1 + q2 * q2 + q3 * q3);
q0 *= recipNorm;
q1 *= recipNorm;
q2 *= recipNorm;
q3 *= recipNorm;
}
void GetEuler(void){
roll = ToDeg(fastAtan2(2 * (q0 * q1 + q2 * q3),1 - 2 * (q1 * q1 + q2 * q2)));
pitch = ToDeg(asin(2 * (q0 * q2 - q3 * q1)));
yaw = ToDeg(fastAtan2(2 * (q0 * q3 + q1 * q2) , 1 - 2* (q2 * q2 + q3 * q3)));
if (yaw < 0){
yaw +=360;
}
}
float fastAtan2( float y, float x)
{
static float atan;
static float z;
if ( x == 0.0f )
{
if ( y > 0.0f ) return PIBY2_FLOAT;
if ( y == 0.0f ) return 0.0f;
return -PIBY2_FLOAT;
}
z = y / x;
if ( fabs( z ) < 1.0f )
{
atan = z/(1.0f + 0.28f*z*z);
if ( x < 0.0f )
{
if ( y < 0.0f ) return atan - PI_FLOAT;
return atan + PI_FLOAT;
}
}
else
{
atan = PIBY2_FLOAT - z/(z*z + 0.28f);
if ( y < 0.0f ) return atan - PI_FLOAT;
}
return atan;
}
float invSqrt(float number) {
volatile long i;
volatile float x, y;
volatile const float f = 1.5F;
x = number * 0.5F;
y = number;
i = * ( long * ) &y;
i = 0x5f375a86 - ( i >> 1 );
y = * ( float * ) &i;
y = y * ( f - ( x * y * y ) );
return y;
}
void Smoothing(float *raw, float *smooth){
*smooth = (*raw * (0.15)) + (*smooth * 0.85);
}
float fscale( float originalMin, float originalMax, float newBegin, float
newEnd, float inputValue, float curve){
float OriginalRange = 0;
float NewRange = 0;
float zeroRefCurVal = 0;
float normalizedCurVal = 0;
float rangedValue = 0;
boolean invFlag = 0;
// condition curve parameter
// limit range
if (curve > 10) curve = 10;
if (curve < -10) curve = -10;
curve = (curve * -.1) ; // - invert and scale - this seems more intuitive - postive numbers give more weight to high end on output
curve = pow(10, curve); // convert linear scale into lograthimic exponent for other pow function
/*
Serial.println(curve * 100, DEC); // multply by 100 to preserve resolution
Serial.println();
*/
// Check for out of range inputValues
if (inputValue < originalMin) {
inputValue = originalMin;
}
if (inputValue > originalMax) {
inputValue = originalMax;
}
// Zero Refference the values
OriginalRange = originalMax - originalMin;
if (newEnd > newBegin){
NewRange = newEnd - newBegin;
}
else
{
NewRange = newBegin - newEnd;
invFlag = 1;
}
zeroRefCurVal = inputValue - originalMin;
normalizedCurVal = zeroRefCurVal / OriginalRange; // normalize to 0 - 1 float
/*
Serial.print(OriginalRange, DEC);
Serial.print(" ");
Serial.print(NewRange, DEC);
Serial.print(" ");
Serial.println(zeroRefCurVal, DEC);
Serial.println();
*/
// Check for originalMin > originalMax - the math for all other cases i.e. negative numbers seems to work out fine
if (originalMin > originalMax ) {
return 0;
}
if (invFlag == 0){
rangedValue = (pow(normalizedCurVal, curve) * NewRange) + newBegin;
}
else // invert the ranges
{
rangedValue = newBegin - (pow(normalizedCurVal, curve) * NewRange);
}
return rangedValue;
}
I am trying to build a head tracker using a Teensy 2.0 and the LSM9DS0 IMU Breakout by adafruit. I connected the following:
Teensy 2.0 -- IMU
D0 --> SCL
D1 --> SDA
GND --> GND
VCC --> VDD
I compiled the following code and uploaded it, rebooted the device. I run joy.cpl and see the Teensy 2.0 which is emulating a joystick/keyboard/mouse, but when I go to properties to test moving the head tracker doesn't move the mouse cursor at all. Am I missing something? Here is the code that I have running as well. Any help is greatly appreciated. This is all based on this blog post: http://planetkris.com/2014/12/easier-better-arduino-imu-head-tracker/
/*
Based on the Madgwick algorithm found at:
See: http://www.x-io.co.uk/open-source-imu-and-ahrs-algorithms/
This code inherits all relevant liscenses and may be freely modified and redistributed.
The MinIMU v1 has a roughly +/- 10degree accuracy
The MinIMU v2 has a roughly +/- 1 degree accuracy
*/
#include <LSM303.h>
#include <L3G.h>
#include <Wire.h>
#define ToRad(x) ((x) * 0.01745329252) // *pi/180
#define ToDeg(x) ((x) * 57.2957795131) // *180/pi
#define PI_FLOAT 3.14159265f
#define PIBY2_FLOAT 1.5707963f
#define GYRO_SCALE 0.07f
#define betaDef 0.08f
//To find the calibration values us the sketch included with the LSM303 driver from pololu
/*Change line 11 from
compass.enableDefault();
to
compass.writeMagReg(LSM303_CRA_REG_M, 0x1C);
compass.writeMagReg(LSM303_CRB_REG_M, 0x60);
compass.writeMagReg(LSM303_MR_REG_M, 0x00);
Then put the calibration values below
*/
#define compassXMin -283.0f
#define compassYMin -186.0f
#define compassZMin -198.0f
#define compassXMax 395.0f
#define compassYMax 488.0f
#define compassZMax 413.0f
#define inverseXRange (float)(2.0 / (compassXMax - compassXMin))
#define inverseYRange (float)(2.0 / (compassYMax - compassYMin))
#define inverseZRange (float)(2.0 / (compassZMax - compassZMin))
#define headingtimeout 20000 //20 sec in ms
// Teensy 2.0 has the LED on pin 11
// Teensy++ 2.0 has the LED on pin 6
// Teensy 3.0 has the LED on pin 13
const int ledPin = 11;
L3G gyro;
LSM303 compass;
long timer, printTimer;
float G_Dt;
int loopCount;
int blinkCount;
float q0;
float q1;
float q2;
float q3;
float beta;
float magnitude;
float pitch,roll,yaw;
float gyroSumX,gyroSumY,gyroSumZ;
float offSetX,offSetY,offSetZ;
float floatMagX,floatMagY,floatMagZ;
float smoothAccX,smoothAccY,smoothAccZ;
float accToFilterX,accToFilterY,accToFilterZ;
int i;
int inithead; //Store initial heading
boolean fixed; //Lock in that heading
int newhead; //360 degree transformation
void setup(){
//Serial.begin(115200);
//Serial.println("Keeping the device still and level during startup will yeild the best results");
pinMode(ledPin, OUTPUT);
digitalWrite(ledPin, HIGH); // set the LED on
delay(100);
Wire.begin();
TWBR = ((F_CPU / 400000) - 16) / 2;//set the I2C speed to 400KHz
IMUinit();
printTimer = millis();
timer = micros();
blinkCount = 0;
inithead = yaw; // Grab an initial heading - expect this to change
fixed = false;
}
void loop(){
if (micros() - timer >= 5000){
//this runs in 4ms on the MEGA 2560
G_Dt = (micros() - timer)/1000000.0;
timer=micros();
compass.read();
floatMagX = ((float)compass.m.x - compassXMin) * inverseXRange - 1.0;
floatMagY = ((float)compass.m.y - compassYMin) * inverseYRange - 1.0;
floatMagZ = ((float)compass.m.z - compassZMin) * inverseZRange - 1.0;
Smoothing(&compass.a.x,&smoothAccX);
Smoothing(&compass.a.y,&smoothAccY);
Smoothing(&compass.a.z,&smoothAccZ);
accToFilterX = smoothAccX;
accToFilterY = smoothAccY;
accToFilterZ = smoothAccZ;
gyro.read();
AHRSupdate(&G_Dt);
//update the joystick heading coordinates
// modify degress for heading
newhead = yaw-inithead;
if(newhead > 180){newhead = -360+newhead;}
else if(newhead < -180){newhead = 360+newhead;}
if (newhead < 0){newhead = fscale(-40, 0, 0, 512, newhead,0);}
else {newhead = fscale(0, 40, 512, 1023, newhead,0);}
if (newhead < 0){newhead = 0;}
if (newhead > 1023){newhead = 1023;}
Joystick.Z(newhead);
}
if (millis() - printTimer > 10){
printTimer = millis();
GetEuler();
//Serial.print("!ANG:"); //This is what MinIMU-9-test.py is looking for
//Serial.print(roll);
if (roll < 0){roll = fscale(-25, 0, 0, 512, roll,0);}
else {roll = fscale(0, 25, 512, 1023, roll,0);}
if (roll < 0){roll = 0;}
if (roll > 1023){roll = 1023;}
Joystick.X(roll);
//Serial.print(",");
//Serial.print(pitch);
if (pitch < 0){pitch = fscale(-25, 0, 0, 512, pitch,0);}
else {pitch = fscale(0, 25, 512, 1023, pitch,0);}
if (pitch < 0){pitch = 0;}
if (pitch > 1023){pitch = 1023;}
Joystick.Y(pitch);
//Serial.print(",");
//Serial.println(yaw);
//DEBUG STUFF
//Serial.println(printTimer);
//Serial.print(smoothedYaw);
//Serial.print(", ");
//Serial.println(roll);
if (fixed == false){
blinkCount++;
if (blinkCount > 15) {digitalWrite(ledPin, HIGH);}
if (blinkCount > 30) {digitalWrite(ledPin, LOW); blinkCount=0;}
if (printTimer > headingtimeout) {inithead = yaw;
fixed = true;
digitalWrite(ledPin, HIGH); // set the LED on
}
}
}
}
void IMUinit(){
//init devices
compass.init();
gyro.init();
gyro.writeReg(L3G_CTRL_REG1, 0xCF);
gyro.writeReg(L3G_CTRL_REG2, 0x00);
gyro.writeReg(L3G_CTRL_REG3, 0x00);
gyro.writeReg(L3G_CTRL_REG4, 0x20); //
gyro.writeReg(L3G_CTRL_REG5, 0x02);
compass.writeAccReg(LSM303_CTRL_REG1_A, 0x77);//400hz all enabled
compass.writeAccReg(LSM303_CTRL_REG4_A, 0x20);//+/-8g 4mg/LSB
compass.writeMagReg(LSM303_CRA_REG_M, 0x1C);
compass.writeMagReg(LSM303_CRB_REG_M, 0x60);
compass.writeMagReg(LSM303_MR_REG_M, 0x00);
beta = betaDef;
//calculate initial quaternion
//take an average of the gyro readings to remove the bias
for (i = 0; i < 500;i++){
gyro.read();
compass.read();
Smoothing(&compass.a.x,&smoothAccX);
Smoothing(&compass.a.y,&smoothAccY);
Smoothing(&compass.a.z,&smoothAccZ);
delay(3);
}
gyroSumX = 0;
gyroSumY = 0;
gyroSumZ = 0;
for (i = 0; i < 500;i++){
gyro.read();
compass.read();
Smoothing(&compass.a.x,&smoothAccX);
Smoothing(&compass.a.y,&smoothAccY);
Smoothing(&compass.a.z,&smoothAccZ);
gyroSumX += (gyro.g.x);
gyroSumY += (gyro.g.y);
gyroSumZ += (gyro.g.z);
delay(3);
}
offSetX = gyroSumX / 500.0;
offSetY = gyroSumY / 500.0;
offSetZ = gyroSumZ / 500.0;
compass.read();
//calculate the initial quaternion
//these are rough values. This calibration works a lot better if the device is kept as flat as possible
//find the initial pitch and roll
pitch = ToDeg(fastAtan2(compass.a.x,sqrt(compass.a.y * compass.a.y + compass.a.z * compass.a.z)));
roll = ToDeg(fastAtan2(-1*compass.a.y,sqrt(compass.a.x * compass.a.x + compass.a.z * compass.a.z)));
if (compass.a.z > 0){
if (compass.a.x > 0){
pitch = 180.0 - pitch;
}
else{
pitch = -180.0 - pitch;
}
if (compass.a.y > 0){
roll = -180.0 - roll;
}
else{
roll = 180.0 - roll;
}
}
floatMagX = (compass.m.x - compassXMin) * inverseXRange - 1.0;
floatMagY = (compass.m.y - compassYMin) * inverseYRange - 1.0;
floatMagZ = (compass.m.z - compassZMin) * inverseZRange - 1.0;
//tilt compensate the compass
float xMag = (floatMagX * cos(ToRad(pitch))) + (floatMagZ * sin(ToRad(pitch)));
float yMag = -1 * ((floatMagX * sin(ToRad(roll)) * sin(ToRad(pitch))) + (floatMagY * cos(ToRad(roll))) - (floatMagZ * sin(ToRad(roll)) * cos(ToRad(pitch))));
yaw = ToDeg(fastAtan2(yMag,xMag));
if (yaw < 0){
yaw += 360;
}
//Serial.println(roll);
//Serial.println(pitch);
//Serial.println(yaw);
//calculate the rotation matrix
float cosPitch = cos(ToRad(pitch));
float sinPitch = sin(ToRad(pitch));
float cosRoll = cos(ToRad(roll));
float sinRoll = sin(ToRad(roll));
float cosYaw = cos(ToRad(yaw));
float sinYaw = sin(ToRad(yaw));
//need the transpose of the rotation matrix
float r11 = cosPitch * cosYaw;
float r21 = cosPitch * sinYaw;
float r31 = -1.0 * sinPitch;
float r12 = -1.0 * (cosRoll * sinYaw) + (sinRoll * sinPitch * cosYaw);
float r22 = (cosRoll * cosYaw) + (sinRoll * sinPitch * sinYaw);
float r32 = sinRoll * cosPitch;
float r13 = (sinRoll * sinYaw) + (cosRoll * sinPitch * cosYaw);
float r23 = -1.0 * (sinRoll * cosYaw) + (cosRoll * sinPitch * sinYaw);
float r33 = cosRoll * cosPitch;
//convert to quaternion
q0 = 0.5 * sqrt(1 + r11 + r22 + r33);
q1 = (r32 - r23)/(4 * q0);
q2 = (r13 - r31)/(4 * q0);
q3 = (r21 - r12)/(4 * q0);
}
void IMUupdate(float *dt) {
static float gx;
static float gy;
static float gz;
static float ax;
static float ay;
static float az;
static float recipNorm;
static float s0, s1, s2, s3;
static float qDot1, qDot2, qDot3, qDot4;
static float _2q0, _2q1, _2q2, _2q3, _4q0, _4q1, _4q2 ,_8q1, _8q2, q0q0, q1q1, q2q2, q3q3;
gx = ToRad((gyro.g.x - offSetX) * GYRO_SCALE);
gy = ToRad((gyro.g.y - offSetY) * GYRO_SCALE);
gz = ToRad((gyro.g.z - offSetZ) * GYRO_SCALE);
ax = -1.0 * compass.a.x;
ay = -1.0 * compass.a.y;
az = -1.0 * compass.a.z;
// Rate of change of quaternion from gyroscope
qDot1 = 0.5f * (-q1 * gx - q2 * gy - q3 * gz);
qDot2 = 0.5f * (q0 * gx + q2 * gz - q3 * gy);
qDot3 = 0.5f * (q0 * gy - q1 * gz + q3 * gx);
qDot4 = 0.5f * (q0 * gz + q1 * gy - q2 * gx);
magnitude = sqrt(ax * ax + ay * ay + az * az);
if ((magnitude > 384) || (magnitude < 128)){
ax = 0;
ay = 0;
az = 0;
}
// Compute feedback only if accelerometer measurement valid (avoids NaN in accelerometer normalisation)
if(!((ax == 0.0f) && (ay == 0.0f) && (az == 0.0f))) {
// Normalise accelerometer measurement
recipNorm = invSqrt(ax * ax + ay * ay + az * az);
ax *= recipNorm;
ay *= recipNorm;
az *= recipNorm;
// Auxiliary variables to avoid repeated arithmetic
_2q0 = 2.0f * q0;
_2q1 = 2.0f * q1;
_2q2 = 2.0f * q2;
_2q3 = 2.0f * q3;
_4q0 = 4.0f * q0;
_4q1 = 4.0f * q1;
_4q2 = 4.0f * q2;
_8q1 = 8.0f * q1;
_8q2 = 8.0f * q2;
q0q0 = q0 * q0;
q1q1 = q1 * q1;
q2q2 = q2 * q2;
q3q3 = q3 * q3;
// Gradient decent algorithm corrective step
s0 = _4q0 * q2q2 + _2q2 * ax + _4q0 * q1q1 - _2q1 * ay;
s1 = _4q1 * q3q3 - _2q3 * ax + 4.0f * q0q0 * q1 - _2q0 * ay - _4q1 + _8q1 * q1q1 + _8q1 * q2q2 + _4q1 * az;
s2 = 4.0f * q0q0 * q2 + _2q0 * ax + _4q2 * q3q3 - _2q3 * ay - _4q2 + _8q2 * q1q1 + _8q2 * q2q2 + _4q2 * az;
s3 = 4.0f * q1q1 * q3 - _2q1 * ax + 4.0f * q2q2 * q3 - _2q2 * ay;
recipNorm = invSqrt(s0 * s0 + s1 * s1 + s2 * s2 + s3 * s3); // normalise step magnitude
s0 *= recipNorm;
s1 *= recipNorm;
s2 *= recipNorm;
s3 *= recipNorm;
// Apply feedback step
qDot1 -= beta * s0;
qDot2 -= beta * s1;
qDot3 -= beta * s2;
qDot4 -= beta * s3;
}
// Integrate rate of change of quaternion to yield quaternion
q0 += qDot1 * *dt;
q1 += qDot2 * *dt;
q2 += qDot3 * *dt;
q3 += qDot4 * *dt;
// Normalise quaternion
recipNorm = invSqrt(q0 * q0 + q1 * q1 + q2 * q2 + q3 * q3);
q0 *= recipNorm;
q1 *= recipNorm;
q2 *= recipNorm;
q3 *= recipNorm;
}
void AHRSupdate(float *dt) {
static float gx;
static float gy;
static float gz;
static float ax;
static float ay;
static float az;
static float mx;
static float my;
static float mz;
static float recipNorm;
static float s0, s1, s2, s3;
static float qDot1, qDot2, qDot3, qDot4;
static float hx, hy;
static float _2q0mx, _2q0my, _2q0mz, _2q1mx, _2bx, _2bz, _4bx, _4bz, _2q0, _2q1, _2q2, _2q3, _2q0q2, _2q2q3, q0q0, q0q1, q0q2, q0q3, q1q1, q1q2, q1q3, q2q2, q2q3, q3q3;
gx = ToRad((gyro.g.x - offSetX) * GYRO_SCALE);
gy = ToRad((gyro.g.y - offSetY) * GYRO_SCALE);
gz = ToRad((gyro.g.z - offSetZ) * GYRO_SCALE);
ax = -1.0 * compass.a.x;
ay = -1.0 * compass.a.y;
az = -1.0 * compass.a.z;
mx = floatMagX;
my = floatMagY;
mz = floatMagZ;
// Rate of change of quaternion from gyroscope
qDot1 = 0.5f * (-q1 * gx - q2 * gy - q3 * gz);
qDot2 = 0.5f * (q0 * gx + q2 * gz - q3 * gy);
qDot3 = 0.5f * (q0 * gy - q1 * gz + q3 * gx);
qDot4 = 0.5f * (q0 * gz + q1 * gy - q2 * gx);
magnitude = sqrt(ax * ax + ay * ay + az * az);
if ((magnitude > 384) || (magnitude < 128)){
ax = 0;
ay = 0;
az = 0;
}
// Compute feedback only if accelerometer measurement valid (avoids NaN in accelerometer normalisation)
if(!((ax == 0.0f) && (ay == 0.0f) && (az == 0.0f))) {
// Normalise accelerometer measurement
recipNorm = invSqrt(ax * ax + ay * ay + az * az);
ax *= recipNorm;
ay *= recipNorm;
az *= recipNorm;
// Normalise magnetometer measurement
recipNorm = invSqrt(mx * mx + my * my + mz * mz);
mx *= recipNorm;
my *= recipNorm;
mz *= recipNorm;
// Auxiliary variables to avoid repeated arithmetic
_2q0mx = 2.0f * q0 * mx;
_2q0my = 2.0f * q0 * my;
_2q0mz = 2.0f * q0 * mz;
_2q1mx = 2.0f * q1 * mx;
_2q0 = 2.0f * q0;
_2q1 = 2.0f * q1;
_2q2 = 2.0f * q2;
_2q3 = 2.0f * q3;
_2q0q2 = 2.0f * q0 * q2;
_2q2q3 = 2.0f * q2 * q3;
q0q0 = q0 * q0;
q0q1 = q0 * q1;
q0q2 = q0 * q2;
q0q3 = q0 * q3;
q1q1 = q1 * q1;
q1q2 = q1 * q2;
q1q3 = q1 * q3;
q2q2 = q2 * q2;
q2q3 = q2 * q3;
q3q3 = q3 * q3;
// Reference direction of Earth's magnetic field
hx = mx * q0q0 - _2q0my * q3 + _2q0mz * q2 + mx * q1q1 + _2q1 * my * q2 + _2q1 * mz * q3 - mx * q2q2 - mx * q3q3;
hy = _2q0mx * q3 + my * q0q0 - _2q0mz * q1 + _2q1mx * q2 - my * q1q1 + my * q2q2 + _2q2 * mz * q3 - my * q3q3;
_2bx = sqrt(hx * hx + hy * hy);
_2bz = -_2q0mx * q2 + _2q0my * q1 + mz * q0q0 + _2q1mx * q3 - mz * q1q1 + _2q2 * my * q3 - mz * q2q2 + mz * q3q3;
_4bx = 2.0f * _2bx;
_4bz = 2.0f * _2bz;
// Gradient decent algorithm corrective step
s0 = -_2q2 * (2.0f * q1q3 - _2q0q2 - ax) + _2q1 * (2.0f * q0q1 + _2q2q3 - ay) - _2bz * q2 * (_2bx * (0.5f - q2q2 - q3q3) + _2bz * (q1q3 - q0q2) - mx) + (-_2bx * q3 + _2bz * q1) * (_2bx * (q1q2 - q0q3) + _2bz * (q0q1 + q2q3) - my) + _2bx * q2 * (_2bx * (q0q2 + q1q3) + _2bz * (0.5f - q1q1 - q2q2) - mz);
s1 = _2q3 * (2.0f * q1q3 - _2q0q2 - ax) + _2q0 * (2.0f * q0q1 + _2q2q3 - ay) - 4.0f * q1 * (1 - 2.0f * q1q1 - 2.0f * q2q2 - az) + _2bz * q3 * (_2bx * (0.5f - q2q2 - q3q3) + _2bz * (q1q3 - q0q2) - mx) + (_2bx * q2 + _2bz * q0) * (_2bx * (q1q2 - q0q3) + _2bz * (q0q1 + q2q3) - my) + (_2bx * q3 - _4bz * q1) * (_2bx * (q0q2 + q1q3) + _2bz * (0.5f - q1q1 - q2q2) - mz);
s2 = -_2q0 * (2.0f * q1q3 - _2q0q2 - ax) + _2q3 * (2.0f * q0q1 + _2q2q3 - ay) - 4.0f * q2 * (1 - 2.0f * q1q1 - 2.0f * q2q2 - az) + (-_4bx * q2 - _2bz * q0) * (_2bx * (0.5f - q2q2 - q3q3) + _2bz * (q1q3 - q0q2) - mx) + (_2bx * q1 + _2bz * q3) * (_2bx * (q1q2 - q0q3) + _2bz * (q0q1 + q2q3) - my) + (_2bx * q0 - _4bz * q2) * (_2bx * (q0q2 + q1q3) + _2bz * (0.5f - q1q1 - q2q2) - mz);
s3 = _2q1 * (2.0f * q1q3 - _2q0q2 - ax) + _2q2 * (2.0f * q0q1 + _2q2q3 - ay) + (-_4bx * q3 + _2bz * q1) * (_2bx * (0.5f - q2q2 - q3q3) + _2bz * (q1q3 - q0q2) - mx) + (-_2bx * q0 + _2bz * q2) * (_2bx * (q1q2 - q0q3) + _2bz * (q0q1 + q2q3) - my) + _2bx * q1 * (_2bx * (q0q2 + q1q3) + _2bz * (0.5f - q1q1 - q2q2) - mz);
recipNorm = invSqrt(s0 * s0 + s1 * s1 + s2 * s2 + s3 * s3); // normalise step magnitude
s0 *= recipNorm;
s1 *= recipNorm;
s2 *= recipNorm;
s3 *= recipNorm;
// Apply feedback step
qDot1 -= beta * s0;
qDot2 -= beta * s1;
qDot3 -= beta * s2;
qDot4 -= beta * s3;
}
// Integrate rate of change of quaternion to yield quaternion
q0 += qDot1 * *dt;
q1 += qDot2 * *dt;
q2 += qDot3 * *dt;
q3 += qDot4 * *dt;
// Normalise quaternion
recipNorm = invSqrt(q0 * q0 + q1 * q1 + q2 * q2 + q3 * q3);
q0 *= recipNorm;
q1 *= recipNorm;
q2 *= recipNorm;
q3 *= recipNorm;
}
void GetEuler(void){
roll = ToDeg(fastAtan2(2 * (q0 * q1 + q2 * q3),1 - 2 * (q1 * q1 + q2 * q2)));
pitch = ToDeg(asin(2 * (q0 * q2 - q3 * q1)));
yaw = ToDeg(fastAtan2(2 * (q0 * q3 + q1 * q2) , 1 - 2* (q2 * q2 + q3 * q3)));
if (yaw < 0){
yaw +=360;
}
}
float fastAtan2( float y, float x)
{
static float atan;
static float z;
if ( x == 0.0f )
{
if ( y > 0.0f ) return PIBY2_FLOAT;
if ( y == 0.0f ) return 0.0f;
return -PIBY2_FLOAT;
}
z = y / x;
if ( fabs( z ) < 1.0f )
{
atan = z/(1.0f + 0.28f*z*z);
if ( x < 0.0f )
{
if ( y < 0.0f ) return atan - PI_FLOAT;
return atan + PI_FLOAT;
}
}
else
{
atan = PIBY2_FLOAT - z/(z*z + 0.28f);
if ( y < 0.0f ) return atan - PI_FLOAT;
}
return atan;
}
float invSqrt(float number) {
volatile long i;
volatile float x, y;
volatile const float f = 1.5F;
x = number * 0.5F;
y = number;
i = * ( long * ) &y;
i = 0x5f375a86 - ( i >> 1 );
y = * ( float * ) &i;
y = y * ( f - ( x * y * y ) );
return y;
}
void Smoothing(float *raw, float *smooth){
*smooth = (*raw * (0.15)) + (*smooth * 0.85);
}
float fscale( float originalMin, float originalMax, float newBegin, float
newEnd, float inputValue, float curve){
float OriginalRange = 0;
float NewRange = 0;
float zeroRefCurVal = 0;
float normalizedCurVal = 0;
float rangedValue = 0;
boolean invFlag = 0;
// condition curve parameter
// limit range
if (curve > 10) curve = 10;
if (curve < -10) curve = -10;
curve = (curve * -.1) ; // - invert and scale - this seems more intuitive - postive numbers give more weight to high end on output
curve = pow(10, curve); // convert linear scale into lograthimic exponent for other pow function
/*
Serial.println(curve * 100, DEC); // multply by 100 to preserve resolution
Serial.println();
*/
// Check for out of range inputValues
if (inputValue < originalMin) {
inputValue = originalMin;
}
if (inputValue > originalMax) {
inputValue = originalMax;
}
// Zero Refference the values
OriginalRange = originalMax - originalMin;
if (newEnd > newBegin){
NewRange = newEnd - newBegin;
}
else
{
NewRange = newBegin - newEnd;
invFlag = 1;
}
zeroRefCurVal = inputValue - originalMin;
normalizedCurVal = zeroRefCurVal / OriginalRange; // normalize to 0 - 1 float
/*
Serial.print(OriginalRange, DEC);
Serial.print(" ");
Serial.print(NewRange, DEC);
Serial.print(" ");
Serial.println(zeroRefCurVal, DEC);
Serial.println();
*/
// Check for originalMin > originalMax - the math for all other cases i.e. negative numbers seems to work out fine
if (originalMin > originalMax ) {
return 0;
}
if (invFlag == 0){
rangedValue = (pow(normalizedCurVal, curve) * NewRange) + newBegin;
}
else // invert the ranges
{
rangedValue = newBegin - (pow(normalizedCurVal, curve) * NewRange);
}
return rangedValue;
}