LSM9DS1 A 9 degree of freedom Inertial Navigation Chip

[espruino-discuss2]

Posted at 2016-11-21 by ClearMemory041063

TestLSM9DS1.js
21 Nov 2016
Using a Pico 1v88

I’m starting work on an I2C driver for the Sparkfun 9DoF Sensor Stick
https://www.sparkfun.com/products/13944
3-axis Magnetometer, Gyro and Accelerometer.
As a starting point I’ve downloaded the Arduino Library from
https://github.com/sparkfun/SparkFun_LSM9DS1_Arduino_Library
The board is scheduled to arrive tomorrow. The attached Espruino code has been derived from the Arduino library. TestLSM9DS1.js
A few functions related to the I2C have been stubbed until the board arrives and testing can begin. Additional functions beyond the basics have yet to be added.
Any suggestions on writing the stubbed I2C functions are welcome.

TestLSM9DS1.js
21 Nov 2016
*/
……
LSM9DS1.prototype.mReadByte=function(subAddress){
//uint8_t LSM9DS1::mReadByte(uint8_t subAddress)
//		return I2CreadByte(_mAddress, subAddress);
  console.log("mReadByte ",_mAddress, subAddress);
  return 0;
};

LSM9DS1.prototype.xgReadByte=function(subAddress){
//uint8_t LSM9DS1::xgReadByte(uint8_t subAddress)
 //return I2CreadByte(_xgAddress, subAddress);
  console.log("xgReadByte ",_xgAddress, subAddress);
return 0;
};
…..
LSM9DS1.prototype.xgWriteByte=function(subAddress,data){
//void LSM9DS1::xgWriteByte(uint8_t subAddress, uint8_t data)
////I2CwriteByte(_xgAddress, subAddress, data);
  console.log("xgWriteByte ",_xgAddress, subAddress, data);
};
……
LSM9DS1.prototype.mWriteByte=function(subAddress,data){
////		return I2CwriteByte(_mAddress, subAddress, data);
  console.log("mWriteByte ",_mAddress, subAddress, data);
  return 0;
};
…..
LSM9DS1.prototype.xgReadBytes=function(subAddress,dest,count){
//void LSM9DS1::xgReadBytes(uint8_t subAddress, uint8_t * dest, uint8_t count){
////	I2CreadBytes(_xgAddress, subAddress, dest, count);
  console.log("xgReadByte ",_xgAddress, subAddress, dest, count);
};
…..
LSM9DS1.prototype.readMag=function(){
//void LSM9DS1::readMag(){
	var temp=Uint8Array(6); // We'll read six bytes from the mag into temp	
	this.mReadBytes(Mags.OUT_X_L_M, temp, 6); // Read 6 bytes, beginning at OUT_X_L_M
 this.mx = (temp[1] << 8) | temp[0]; // Store x-axis values into mx
 this.my = (temp[3] << 8) | temp[2]; // Store y-axis values into my
 this.mz = (temp[5] << 8) | temp[4]; // Store z-axis values into mz
};

LSM9DS1.prototype.mReadBytes=function(subAddress,dest,count){
//void LSM9DS1::mReadBytes(uint8_t subAddress, uint8_t * dest, uint8_t count){
 ////I2CreadBytes(_mAddress, subAddress, dest, count);
  console.log("mReadBytes ",_mAddress, subAddress, dest, count);
};

The current output of the stubbed code:

>15
mReadByte  30 15
xgReadByte  107 15
xgWriteByte  107 16 192
xgWriteByte  107 17 0
xgWriteByte  107 18 0
xgWriteByte  107 30 58
xgWriteByte  107 19 0
xgWriteByte  107 31 56
xgWriteByte  107 32 192
xgWriteByte  107 33 0
mWriteByte  30 32 28
mWriteByte  30 33 0
mWriteByte  30 34 0
mWriteByte  30 35 12
mWriteByte  30 36 0
0
xgReadByte  107 40 new Uint8Array(6) 6
xgReadByte  107 24 new Uint8Array(6) 6
mReadBytes  30 40 new Uint8Array(6) 6
Acceleration  0 0 0
Gyro          0 0 0
Magnetometer  0 0 0
187
LSM9DS1 {
  "i2c": I2C {
    "_options": { "scl": B6, "sda": B9 }
   },
  "addr": 72, "gain": 2048,
  "gBias": [ 0, 0, 0 ],
  "aBias": [ 0, 0, 0 ],
  "mBias": [ 0, 0, 0 ],
  "gBiasRaw": [ 0, 0, 0 ],
  "aBiasRaw": [ 0, 0, 0 ],
  "mBiasRaw": [ 0, 0, 0 ],
  "commInterface": 0, "agAddress": 107, "mAddress": 30, "gyro_enabled": true, "gyro_enableX": true,
  "gyro_enableY": true, "gyro_enableZ": true, "gyro_scale": 245, "gyro_sampleRate": 6, "gyro_bandwidth": 0,
  "gyro_lowPowerEnable": false, "gyro_HPFEnable": false, "gyro_HPFCutoff": 0, "gyro_flipX": false, "gyro_flipY": false,
  "gyro_flipZ": false, "gyro_orientation": 0, "gyro_latchInterrupt": true, "accel_enabled": true, "accel_enableX": true,
  "accel_enableY": true, "accel_enableZ": true, "accel_scale": 2, "accel_sampleRate": 6, "accel_bandwidth": -1,
  "accel_highResEnable": false, "accel_highResBandwidth": 0, "mag_enabled": true, "mag_scale": 4, "mag_sampleRate": 7,
  "mag_tempCompensationEnable": false, "mag_XYPerformance": 3, "mag_ZPerformance": 3, "mag_lowPowerEnable": false, "mag_operatingMode": 0,
  "temp_enabled": true, "ax": 0, "ay": 0, "az": 0, "gx": 0,
  "gy": 0, "gz": 0, "mx": 0, "my": 0, "mz": 0 }

---

Attachments:

• TestLSM9DS1.js

[espruino-discuss2]

Posted at 2016-11-30 by ClearMemory041063

LSM9DS1

Finally the board arrived a week later than expected. I also ordered an ESP32 board which required using a for profit shipping company instead of the post office for some reason. They shipped it from Colorado to Chicago and then mailed it to the suburbs.
The pony express would have been faster.

Problems encountered when implementing the I2C interface:

LSM9DS1.prototype.xgReadBytes=function(subAddress,count){
var dest= new Uint8Array(count);
//  console.log("xgReadBytes ",this.xgAddress, subAddress|0x80, dest, count);
  var x=this.xgAddress;
  this.i2c.writeTo(x, subAddress|0x80);
 dest=this.i2c.readFrom(x, count);
//  for(var i=0;i<count;i++)console.log(dest[i]);
  return dest;
};

LSM9DS1.prototype.mReadBytes=function(subAddress,count){
// console.log("mReadBytes ",this.mAddress, subAddress|0x80,count);
  var x=this.mAddress;
  var dest=new Uint8Array(count);
  this.i2c.writeTo(x, subAddress|0x80);
  dest=this.i2c.readFrom(x, count);
//  for(var i=0;i<count;i++)console.log(dest[i]);
  return dest;
};

Notice the var x=this.address.
If this.address was used in the this.i2c.ReadFrom() function timeout errors occurred.
I tried to create a simplified version of the problem but have not succeeded in reproducing the error.
For reads of multiple bytes bit 7 of the sub-address is set to 1.

LSM9DS1.prototype.readAccel=function(){
var temp=this.xgReadBytes(Regs.OUT_X_L_XL, 6); // Read 6 bytes, beginning at OUT_X_L_XL
 this.ax=this.twos_comp(temp[0],temp[1]);
 this.ay=this.twos_comp(temp[2],temp[3]);
 this.az=this.twos_comp(temp[4],temp[5]);
/*
 this.ax = (temp[1] << 8) | temp[0]; // Store x-axis values into ax
 this.ay = (temp[3] << 8) | temp[2]; // Store y-axis values into ay
 this.az = (temp[5] << 8) | temp[4]; // Store z-axis values into az
*/
  if (_autoCalc)
	{
		ax -= aBiasRaw[X_AXIS];
		ay -= aBiasRaw[Y_AXIS];
		az -= aBiasRaw[Z_AXIS];
	}
};

LSM9DS1.prototype.twos_comp=function(low,high){
 var t=(high << 8) | low;
  return(t & 0x8000 ? t - 0x10000 : t);
};

The values returned are in two’s compliment.

LSM9DS1.prototype.readTemp=function(){
//void LSM9DS1::readTemp(){
 // We'll read two bytes from the             temperature sensor into temp
var temp=this.xgReadBytes(Regs.OUT_TEMP_L, 2); // Read 2 bytes,     beginning at OUT_TEMP_L
//  console.log("TT= ",temp[0].toString(16),temp[1].toString(16));
this.temperature = temp[1];//(temp[1] << 8) | temp[0];
//temperature = ((int16_t)temp[1] << 8) | temp[0];

//https://gist.github.com/jimblom/08b333892ee383d6e443
//temperature = (((int16_t) temp[1] << 12) | temp[0] << 4 ) >> 4; // Temperature is a 12-bit signed integer
//var t= (((temp[1]^0xf)<<12)|temp[0])>>4;
//this.temperature=(t & 0x8000 ? t - 0x10000 : t);
};

There is quite a bit of discussion on the web about reading the temperature.
Having tried various solutions, I’m still not sure it is working properly.
The file TestLSM9DS1_d.js is attached.
Some sample output:

Acceleration  -0.0087890625 -0.09417724609 1.02032470703
Gyro          -810 294 75
Magnetometer  1379 1413 -2029
Temperature  246
Level -0.49353282241 -5.27352997140
heading 44.30230651281
Acceleration  -0.01861572265 -0.09045410156 1.02691650390
Gyro          -605 283 41
Magnetometer  1425 1387 -2030
Temperature  246
Level -1.03853188194 -5.03380446489
heading 45.77422016492
Acceleration  0.00439453125 -0.08666992187 1.02276611328
Gyro          -429 -248 8
Magnetometer  1385 1459 -2064
Temperature  246
Level 0.24618193820 -4.84371267720
heading 43.50951784922
Acceleration  -0.00036621093 -0.08117675781 1.03289794921
Gyro          -501 21 -87
Magnetometer  1373 1453 -2027
Temperature  246
Level -0.02031404967 -4.49371112382
heading 43.37847185456

The readall function:

function readall(W){
W.readAccel();
W.readGyro();
W.readMag();
W.readTemp();
var pirate=180.0/Math.PI;
console.log("Acceleration ",W.ax/16384,W.ay/16384,W.az/16384);
console.log("Gyro         ",W.gx,W.gy,W.gz);
console.log("Magnetometer ",W.mx,W.my,W.mz);
console.log("Temperature ",W.temperature);
console.log("Level", pirate*Math.atan2(W.ax,W.az),pirate*Math.atan2(W.ay,W.az));
console.log("heading",pirate*Math.atan2(W.mx,W.my));
}//end readall

---

Attachments:

• TestLSM9DS1_d.js

[gfwilliams]

Posted at 2016-11-30 by @gfwilliams

Great - thanks for posting up!

Could your timeout error have been from doing something like:

doSomething(this.data);
setTimeout(function() {
  doSomething(this.data);
}, 100);

That's a common 'gotcha' in JS, since this doesn't stay the same inside a setTimeout or interval.

[espruino-discuss2]

Posted at 2016-12-01 by ClearMemory041063

So far the Arduino code for the LSM9DS1 has been ported to Espruino, but to make it really useful it should be worked into module form.
There are a lot of knobs on the virtual control panel for this chip. In the previous version any changes to the knobs needed to be edited in the LSM9DS1.prototype.init function.
Today the code is modified so that the knobs are initialized to default values and an optional set of options can be supplied to the LSM9DS1.prototype.init function.
This is accomplished by changing the init function to the following

LSM9DS1.prototype.init=function(options){
  var i,j;
  for (i=0; i<3; i++){
  this.gBias[i] = 0;
  this.aBias[i] = 0;
  this.mBias[i] = 0;
  this.gBiasRaw[i] = 0;
  this.aBiasRaw[i] = 0;
  this.mBiasRaw[i] = 0;
 }
//process and changes from options
if(typeof options === "undefined" )
  console.log("options undefined");
if(typeof options !== "undefined"){
  console.log("options defined");
 for(i in options){
//console.log(options);
  if(options.hasOwnProperty(i)){
  for(j in this){//LSM9DS1){
//     console.log(i,j);//,options[i],LSM9DS1[j]);
   if(j==i){
     console.log(i,j,options[i],this[j]);
     this[j]=options[i];
   }
  }
 }
}
}
};

The optional options are outlined in the attached file options.js.
For example to change the acceleration sample rate from 6 to 5 :

	// accel sample rate can be 1-6
	// 1 = 10 Hz    4 = 238 Hz
	// 2 = 50 Hz    5 = 476 Hz
	// 3 = 119 Hz   6 = 952 Hz
	accel_sampleRate: 6,

The code that calls the init function uses an option object containing only the options we wish to change.

function start(){
I2C3.setup({ scl :A8, sda: B4} );
var W=new LSM9DS1(I2C3);

var myoptions={ //make changes to basic configuration here
  xgAddress: 0x6B,
  mAddress: 0x1e,
  test: 1,
  accel_sampleRate: 5,
};

W.init(myoptions);
//W.init();
console.log(W.begin());
var nn=setInterval(function () {
    readall(W);
}, 200);
}

The output of the substitutions made in the init function:

>options defined
xgAddress xgAddress 107 107
mAddress mAddress 30 30
test test 1 0
accel_sampleRate accel_sampleRate 5 6

---

Attachments:

• options.js
• TestLSM9DS1_f.js

[gfwilliams]

Posted at 2016-12-02 by @gfwilliams

This looks great - thanks! Looks like it could be ready to publish as a module soon? You could put options.js into the documentation file as a bit of code...

[espruino-discuss2]

Posted at 2016-12-02 by ClearMemory041063

Hi @gordon. It’s tempting to go to module on this project but it’s not quite ready for that as yet. There are a number of functions that have yet to be translated. The most important one being the gyroscope calibration function. There are interrupt functions that would be difficult to use with the Sparkfun board but could be of use with the more expensive Adafruit board that brings forth the interrupt pins.
https://www.sparkfun.com/products/13944
https://www.adafruit.com/product/2021

As to the topic of modules, I’m looking at a module within a module design for the final product.
The lowest level module uses a table to initialize the chip and functions to read the data.

var xgstack=
[
  { "address": 107, "sub": 16, "data": 0 },
  { "address": 107, "sub": 17, "data": 0 },
  { "address": 107, "sub": 18, "data": 0 },
  { "address": 107, "sub": 30, "data": 58 },
  { "address": 107, "sub": 19, "data": 0 },
  { "address": 107, "sub": 31, "data": 56 },
  { "address": 107, "sub": 32, "data": 160 },
  { "address": 107, "sub": 33, "data": 0 }
 ];
var mstack=
[
  { "address": 30, "sub": 32, "data": 28 },
  { "address": 30, "sub": 33, "data": 0 },
  { "address": 30, "sub": 34, "data": 0 },
  { "address": 30, "sub": 35, "data": 12 },
  { "address": 30, "sub": 36, "data": 0 }
 ];
LSM9DS1.prototype.run=function(){
 var i;
 // To verify communication, we can read from the WHO_AM_I register //of each device. Store those in a variable so we can return them.
var mTest = this.mReadByte(Mags.WHO_AM_I_M);// Read the gyro 
var xgTest = this.xgReadByte(Regs.WHO_AM_I_XG);//Read the accel/mag 
var whoAmICombined = (xgTest << 8) | mTest;
console.log("who= ",whoAmICombined);
if (whoAmICombined != ((WHO_AM_I_AG_RSP << 8) | WHO_AM_I_M_RSP))
		return 0;
 for(i=0; i<this.xgstack.length;i++){
   console.log(this.xgstack[i].address, this.xgstack[i].sub,this.xgstack[i].data);
  this.i2c.writeTo(this.xgstack[i].address, this.xgstack[i].sub,this.xgstack[i].data);
 }
 for(i=0; i<this.mstack.length;i++){
  console.log(this.mstack[i].address, this.mstack[i].sub,this.mstack[i].data);
  this.i2c.writeTo(this.mstack[i].address, this.mstack[i].sub,this.mstack[i].data);
 }
return whoAmICombined;
};

See attached file: aTestLSM9DS1_a.js
At the next level of module, which invokes the first level module, the init function parses the options and the begin function populates the xgstack and mstack arrays.
This mod level module uses more memory resources but allows the tweaking of the options. Once the user is satisfied with the tweak, the stacks and some other variables are copied and pasted into a new program that uses only the first module. This will reduce the memory usage in a final program.
A similar approach seems possible for adding the calibration and interrupt functions.
A lowest level module example

//TestM1.js 1 Dec 2016
function LSM9DS1() {
}
LSM9DS1.prototype.add=function(){
  this.a=1;
  this.b=20;
  console.log(this.a+this.b);
};

// Create an instance of LSM9DS1
exports.connect = function() {
  return new LSM9DS1();
};

A module one level up:

/TestM2.js 1 Dec 2016
exports.connect = function() {
  var x=  require("testm1").connect();
x.d=98;
x.sub= function() {
   console.log(this.a-this.b);
  };
  return x;
};

Invoke TestM1

//tryTestM1.js 1 Dec 2016
var ads =require("testm1").connect();
ads.add();

Invoke TestM2

//tryTestM2.js 1 Dec 2016
var ads =require("testm2").connect();
ads.add();
console.log(ads.d);
ads.sub();

Some useful resource links on the topic of using IMU sensors:
https://www.intorobotics.com/accelerometer-gyroscope-and-imu-sensors-tutorials/
http://tutorial.cytron.com.my/2012/01/10/measuring-tilt-angle-with-gyro-and-accelerometer/
Kalman filter simulation
https://www.cs.utexas.edu/~teammco/misc/kalman_filter/

Attachments:

• aTestLSM9DS1_a.js
• TestM1.js
• testm2.js
• tryTestM1.js
• tryTestM2.js

[espruino-discuss2]

Posted at 2016-12-04 by ClearMemory041063

LSM9DS1 4 Dec 2016
Some progress on the calibration functions has been made. There are some problems that need to be addressed.
The first item is the word calibration itself. The functions only address part of a full calibration, the zero point. The scale is not calibrated, but simply uses the advertised values from the data sheet.
The second item is the method used to determine the zero point. For this chip there are two different calibration functions. One calibrates the accelerometer/gyro and the other calibrates the magnetometer. Addressing the accelerometer/gyro function first.
The accelerometer/gyro calibration function for the LSM9DS1 chip makes use of the FIFO hardware. The function sets up the FIFO to read 32 samples each from the accelerometer and gyro, then it averages these values to find the zero offset. The accelerometer makes the assumption that the x-y plane is parallel to a level surface, and that the z-axis is on a plumb line. It doesn’t actually find a zero offset for the z-axis.
This can be corrected by doing the x-y calibration, reposition the chip so that either the x-z or y-z plane is level and finding the zero for the z-axis.
Of note is Figure 1 in the LSM9DS1 datasheet. Notice the dot on the chip is positioned differently for the magnetometer illustration. Also as drawn the axis directions are a left-hand coordinate system.
http://www.st.com/content/ccc/resource/technical/document/datasheet/1e/3f/2a/d6/25/eb/48/46/DM00103319.pdf/files/DM00103319.pdf/jcr:content/translations/en.DM00103319.pdf
A bug was found in the previous code that froze the gyro readings. The gyro sample rate has been added to fix the bug.

this.gyro_scale = 245;
this.gyro_sampleRate = 6;
this.gyro_bandwidth = 0;

Once calibrated using calls to the read accelerometer and read gyro functions with the FIFO produce an unreasonable variation in the at rest gyro readings. This variation is greatly reduced by using the FIFO in continuous mode, even limiting the FIFO to 2 samples. My hypothesis is that without the FIFO the values returned contain incomplete samples. To use the FIFO in continuous mode:

// fifoMode
// FIFO_OFF = 0, FIFO_THS = 1,	FIFO_CONT_TRIGGER = 3, 
//FIFO_OFF_TRIGGER = 4, FIFO_CONT = 5
W.enableFIFO(true);
 W.setFIFO(5,10); // ( fifoMode ,length<32)

The magnetometer calibration function acquires 128 readings and for each axis determines the maximum and minimum reading, and then averages these two values to produce the zero offset value for each axis. These values are stored on the chip using a call to the magOffset function.
I’m not sure if this method is of any value. I can imagine placing the chip inside a pair of A.C Helmholtz coils as one method. I finally performed a zero offset calibration manually.
I attached the chip to a cube. I placed the cube on a level non-magnetic surface (wood) with a wooden fence (think table saw) oriented North South. I zeroed the chip offsets using a call to the magOffset function. Then I collected six sets of data.

1. X-axis level and pointing North
2. X-axis level and pointing South
3. Y-axis level and pointing North
4. Y-axis level and pointing South
5. Z-axis level and pointing North
6. Z-axis level and pointing South
   Then I used a spreadsheet to find the maximum and minimum values in pairs of data sets and averaged them. For the X offset use sets 1 and 2, for Y sets 2 and 3 and finally for Z sets 5 and 6.
   These offsets are then sent to the chip after initialization using the magOffset function.
   If the chip is powered down the offset values are lost (volatile).
   This procedure finally produced reasonable compass heading values when the x-y plane of the chip is level. Yet to address is the heading in 0 to 360 degrees instead of -180 to 180 degrees in the wrong direction. Also I hope to add the necessary rotation matrix math that gives the compass heading in any chip orientation.

Attached is the code as of today. I hope to incorporate changes that will reflect the issues discussed.

[espruino-discuss2]

Posted at 2016-12-04 by ClearMemory041063

Problem posting the file.
I posted the wrong file and then removed it.
It wouldn't take the correct file.
When I did the post I got an error page.
It did post but no attached file.
Attached is the file

---

Attachments:

• aTestLSM9DS1_f.js

[gfwilliams]

Posted at 2016-12-05 by @gfwilliams

Thanks! Yeah, calibrating is a real pain. I've even noticed with the Pucks that if you bring a magnet too close (<2cm from the case) then it can partially magnetise something on the Puck and you have to recalibrate!

For working out the heading, have you come across Math.atan2? It's amazingly helpful.

I really quick hack would be something like this:

if (is_biggest(accel.x)) return sign(accel.x)*Math.atan2(mag.y, mag.z);
if (is_biggest(accel.y)) return sign(accel.y)*Math.atan2(mag.z, mag.x);
return sign(accel.z)*Math.atan2(mag.x, mag.y);

But I guess to do it properly you want to do it better than the nearest 90 degrees :)

[espruino-discuss2]

Posted at 2016-12-05 by ClearMemory041063

That's a cool hack. What we call Q&D (quick and dirty).
Aran2 gives -180 to 180.
theta=atan2(z,x)
if(theta<0) theta+=360. Then theta ranges from 0 to 360
For the left handed axis on this chip theta= atan(-z/x)

Using the accelerometer readings gx, gy, gz
theta = atan2(gz,gx), phi=atan2(gz,gy)
rotate around yaxis
x1=gx, y1=cos(theta)*gy-sin(theta)*gz, z1=sin(theta)*gy+cos(theta)*gz
the rotate around the xaxis
x2=cos(phi)*x1+sin(phi)*z1, y2=y1, z2=-sin(phi)*x1+cos(phi)*z1
At which point z2 should be -1. X2 and Y2 should be zero
If the rotations are them applied to the magnetometer readings the compass can be leveled.
Some gotchas:
May need a minus sign in the atan2(-a/b)
May need to rotate the opposite direction by changing the sign on the sin terms( +sin becomes -sin, and -sin becomes +sin)
I captured some data earlier this morning and did some of this in a spreadsheet. It looks like it works but I want to finish the mounting fixture and change the code to load the zero calibrations rather than recalibration on each run.

                     X	Y	Z	atan2(x/z)	atan2(y/z)

Acceleration -0.000249863 0.003465652 1.000553131 -0.014308162 0.198456693

[espruino-discuss2]

Posted at 2016-12-05 by ClearMemory041063

Tab made it post so I'll try again

	                     X	                             Y              	Z	                 atan2(z,x)	atan2(z,y)
Acceleration	-0.000249863	0.003465652	1.000553131	-0.014308162	0.198456693

sin(theta)	cos(theta)	sin(phi)	cos(phi)
-0.000249725	0.999999969	0.003463716	0.999994001

           X1	                     Y1                	Z1	            X2	          Y2	              Z2
-0.000249863	0.003715515	1.000552234	0.003215767	0.003715515	1.000546232

Preview takes out the spaces that I tried to make the headings line up.
Better examples to follow.

[gfwilliams]

Posted at 2016-12-06 by @gfwilliams

If you treat your stuff like code (with the three backticks) then you should be able to get it to appear a bit better (I changed it above).

I think it's just a typo, but you wrote atan2(y/z), when you need either atan(y/z) or atan2(y,z)

atan2 is clever, because 12/34 and -12 / -34 should be different angles, but obviously evaluate to the same number. atan2 checks and makes sure that it outputs a value that represents all 360 degrees, and not just 180.

[espruino-discuss2]

Posted at 2016-12-06 by ClearMemory041063

NormalizeG.js
NormalizeG.wxm
6 Dec 2016
Attached are two files that use matrix rotations on an xyz vector to produce a vector where x1=0,y1=0,z1= - sqrt(x^2+y^2+z^3)
It’s still need some work as the matrix direction values depend on the vector quadrant.
This is likely the result of computerizing the trig and algebra.
The goal is to use the matrices and accelerometer readings to level the magnetometer readings and produce a compass heading.
The file with the wxm extension can be opened using the Maxima software.
This allows an analytic derivation as well as a numerical one.
http://maxima.sourceforge.net/

Attachments:

• normalizeG.wxm
• rotation3.js

[espruino-discuss2]

Posted at 2016-12-06 by ClearMemory041063

Now working for all 8 quadrants.
On to doing the rotations for the magnetometer vector to do final proof of concept.
Then to see if pre-multiplying the matrices (using Maxima) and using simpler code will work.
Finally how well will it work with data from the chip?
Didn't use atan2. used the abs(atan) and then the sign of the original x,y values to set the matrix rotation direction and the z value to control if the final matrix is needed.

Attachments:

• rotation4.js

[espruino-discuss2]

Posted at 2016-12-11 by Eduard

I am trying to use LSM9DS1 with JavaScript. My setup is Sparkfun LSM9DS1 connected to Arduino, and then connected via Serial port to a laptop. I have node.js on a laptop. I tried Johnny-five, but it does not support LSM9DS1. Your code seems to be the only JavaScript code for that IMU.
Any advise on getting it to work on my current setup?

[espruino-discuss2]

Posted at 2016-12-11 by ClearMemory041063

Hi Eduard. The Sparkfun site has C code for Arduino. This JavaScript code is under development at the moment. I plan to post some revisions in a few days. Currently I'm using a Pico with Espruino. I have not tested it on other versions of hardware. It seems plausible that it would run on other hardware running Espruino that has I2C interface. Defining the I2C pins would be the first item on a list of things to get the code running on different hardware running Espruino.
I have zero experience with the Johnny-five system.

[espruino-discuss2]

Posted at 2017-05-07 by ClearMemory041063

Converting the Raw Magnetometer Counts to Calibrated Engineering Units

The ideal case

Three magnetometer sensors place on three orthogonal axis X, Y and Z.
Each magnetometer produces an output of 0.0 when exposed to a zero magnetic field and the same values when each axis is point at the Earth’s magnetic pole.

The real world magnetometer chip

Each axis has to have an offset value applied to the raw counts to obtain a zero.
For a given magnetic field each axis may produce a slightly different value.
The axis may not be perfectly orthogonal.

Some math:

Let X, Y and Z be the raw readings obtained from the magnetometer.
Let Xoffset, Yoffset and Zoffset be the zero offset that is applied to each axis X, Y and Z to obtain
X1 = X – Xoffset, Y1= Y - Yoffset, and Z1 = Z – Zoffset.
Let X2 = XAX1 + XBY1 + XCZ1,
Let Y2 = YAX1 + YBY1 + YCZ1,
Let Z2 = ZAX1 + ZBY1 + ZC*Z1, where
XA, XB, XC,
YA, YB, YC, and
ZA, ZB, ZC are calibration values

Let R = sqrt ( X2 ^2 + Y2^2 + Z2^2), and
For a large number of samples let avgR = sumof( Rn)/N, the average radius.
Let Error(n) = R(n)- avgR, and Error^2(n)= Error(n) * Error(n).
Finally SumError^2 = sumof(Error^2(n))
All this is done in the attached spreadsheet.

Collect some calibration data using the Magtest.js code.

Start the program and point each axis of the magnetometer toward the North magnetic pole.
At my location the pole is 60 degrees below the horizon. Each axis has to be point at and away from the pole to get a good calibration sample. When calibrated the magnetic radius R should be a constant ( at least statistically.

Finding the zero offsets and calibration values

The raw data are then pasted into the spreadsheet X, Y , and Z columns.

	raw	raw	raw
N	X	Y	Z
0	-735	478	118
1	-700	555	38
2	-660	645	-26
...	More data

The X1 etc. columns have to be copied and pasted such that each XYZ sample is calculated.

raw-offset

X1	Y1	Z1	X2	Y2	Z2	R	Error^2
-1795.01	461.26	-438.90	-1756.92	235.48	-478.70	1836.13	35.58
-1760.01	538.26	-518.90	-1721.45	315.47	-557.92	1836.90	45.29

The formula view:

raw-offset

X1	Y1	Z1
=+B11-$B$3	=+C11-$B$4	=+D11-$B$5
=+B12-$B$3	=+C12-$B$4	=+D12-$B$5

X2	Y2	Z2
=+$E11*$C$3+$F11*$D$3+$G11*$E$3	=+$E11*$C$4+$F11*$D$4+$G11*$E$4	=+$E11*$C$5+$F11*$D$5+$G11*$E$5
=+$E12*$C$3+$F12*$D$3+$G12*$E$3	=+$E12*$C$4+$F12*$D$4+$G12*$E$4	=+$E12*$C$5+$F12*$D$5+$G12*$E$5

R	Error^2
=+SQRT(H11H11+I11I11+J11*J11)	=+(K11-$K$8)^2
=+SQRT(H12H12+I12I12+J12*J12)	=+(K12-$K$8)^2

The calculation range in Cells K8 and L7 have to be adjusted to fit the data range.

J	K	L
	Sumerr^2	243533.8512
Avg R=	1830.168415

J	K	L
	Sumerr^2	=+SUM(L11:L163)
Avg R=	=+AVERAGE(K11:K163)

We start with the offsets in B3 ,B4, and B5 set to zero and the calibration values
Cells C3,D4, and E5 equal to 1
Cells C4, C5, D3, D5, E3, and E4 equal to 0.0.

	Offset	A	B	C
X	0	1	0	0
Y	0	0	1	0
Z	0	0	0	1

The Solver function of Excel (part of the analysis tool pack add in) is used to find the offsets and calibration coefficients.
Track your progress by copying the value in cell L8 into a progress column.
First use the solver to minimize cell L8 by changing cells B3, B4, and B5.
The value in cell L8 should be smaller and cells B3, B4, and B5 should have changed.

	Offset	A	B	C
X	956.5255249	1	0	0
Y	57.48926514	0	1	0
Z	564.9867808	0	0	1

Apply solver once again this time minimizing cell L8 by changing cells
C3, C4, C5, D3, D4, D5, E3, and E4. Note that cell E5 is left to have a value of 1.0.
At this point the error squared should been reduced by a lot.

	Offset	A	B	C
X	1060.011759	0.982416927	0.014146407	0
Y	16.73968712	0.121577401	0.983634984	0
Z	556.9017955	0.02217041	0	1

I use the Descriptive Statistics function in the analysis tool pack to analyze the X2, Y2, Z2, and R values.

	R	X2	Y2	Z2
Mean	1829.74	-364.59	391.43	632.47
Standard Error	3.23	67.06	76.42	84.77
Median	1829.47	-437.90	486.95	869.72
Standard Deviation	39.96	829.43	945.26	1048.54
Sample Variance	1597.08	687950.89	893521.30	1099436.03
Kurtosis	13.36	-0.80	0.03	-0.81
Skewness	-1.24	0.03	-0.81	-0.70
Range	400.83	3116.84	3511.30	3364.00
Minimum	1589.21	-1839.88	-1767.80	-1533.31
Maximum	1990.03	1276.96	1743.49	1830.68
Sum	279950.92	-55782.91	59888.09	96768.49
Count	153.00	153.00	153.00	153.00

Additional measures that may be applied is to remove data that produces an R value more than two standard deviations from the average R, and then recalculate the calibration values.

---

Attachments:

• Mag8Gauss.ods
• Magtest.js

[espruino-discuss2]

Posted at 2017-05-10 by ClearMemory041063

Elimination of data outside of 2 standard deviations

The following cell formulas were used to flag data with R > Ravg + 2* Standard Deviation, data with R < Ravg – 2 *Standard Deviations. Addif combines the two test. Sort is a copy of sort but pasting the values.
The data set is then sorted on the sort column so that the data that fails the two test appears at the end.
The range of the average R and error squared cells is then adjusted to omit the failed data.

If>	If<	addif	sort
=+IF(K11>2*$W$16+$K$8,1,0)	=+IF(K11<-2*$W$16+$K$8,1,0)	=+M11+N11	0
=+IF(K12>2*$W$16+$K$8,1,0)	=+IF(K12<-2*$W$16+$K$8,1,0)	=+M12+N12	0
=+IF(K13>2*$W$16+$K$8,1,0)	=+IF(K13<-2*$W$16+$K$8,1,0)	=+M13+N13	0

The statistics before and after culling points

	X2	Y2	Z2	R	R culled
Mean	-364.5748567	391.871392	632.4737844	1830.168415	1836.695918
Standard Error	67.04595875	76.48066792	84.76943069	3.236027167	1.512956317
Median	-437.737373	492.0129977	869.7152389	1831.87751	1837.17791
Mode	#N/A	#N/A	#N/A	#N/A	#N/A
Standard Deviation	829.3127091	946.0136164	1048.53995	40.02744545	18.1554758
Sample Variance	687759.5696	894941.7624	1099436.026	1602.19639	329.6213015
Kurtosis	-0.804853975	0.040187749	-0.812408283	13.51531831	1.605392491
Skewness	0.029365323	-0.813405054	-0.704273669	-1.200036996	0.376826799
Range	3116.687258	3519.235059	3363.996524	402.5993238	125.1034715
Minimum	-1839.702418	-1770.78729	-1533.311636	1588.830427	1780.98384
Maximum	1276.984841	1748.447769	1830.684887	1991.429751	1906.087312
Sum	-55779.95308	59956.32298	96768.48901	280015.7674	264484.2122
Count	153	153	153	153	144

Compare the Range of the R and R culled items.

The calibration constants

Mag8Gauss 30Apr2017

	Offset	A	B	C
X	1060.852426	0.987424002	0.01417124	-0.000599842
Y	24.46995621	0.124389675	0.996380859	-0.000561968
Z	561.2217795	0.020594208	0.00552387	1

Next using the calibrations.

---

Attachments:

• Mag8GaussA.ods

[espruino-discuss2]

Posted at 2017-05-10 by ClearMemory041063

Applying the Calibrations

There are 4 values to be applied to 3 axis, for each scale and for the magnetometer, accelerometer and the gyroscope sensors.

A data structure for the magnetometer calibration values

var magcal={
  scale4:{scale:4,table:[
  {offset:0,A:1,B:0,C:0},
  {offset:0,A:0,B:1,C:0},
  {offset:0,A:0,B:0,C:1}
  ]},
  scale8:{scale:4,table:[
  {offset:1060.85,A:0.98742,B:0.01417,C:-0.0005998},
  {offset:24.469956,A:	0.124389675,B:0.996380859,C:-0.000561968},
  {offset:561.2217795,A:0.020594208	,B:0.00552387,C:1}
  ]},
  scale12:{scale:4,table:[
  {offset:0,A:1,B:0,C:0},
  {offset:0,A:0,B:1,C:0},
  {offset:0,A:0,B:0,C:1}
  ]},
  scale16:{scale:4,table:[
  {offset:0,A:1,B:0,C:0},
  {offset:0,A:0,B:1,C:0},
  {offset:0,A:0,B:0,C:1}
  ]},
};

Code to apply the calibration values

function useCalibration(cal,autocalc,data){
 var i;var D=[0,0,0];var F=[0,0,0];
if(autocalc<1){
  for(i=0;i<3;i++)D[i]=data[i];
  return D;
}//endif
 for(i=0;i<3;i++)D[i]=data[i]-cal.table[i].offset;
if(autocalc===1)return D;
for(i=0;i<3;i++){
  F[i]=D[0]*cal.table[i].A;
  F[i]+=D[1]*cal.table[i].B;
  F[i]+=D[2]*cal.table[i].C;
}//next i
for(i=0;i<3;i++)F[i]=F[i]*cal.scale/(1<<15);
 return F;
}//end useCalibration

Applying the Use calibration function

function displayMag(){
var m;
if(W.Mread(W.MREGval.ZYXDA)){  //new data available
// console.log("Mag data available");
 m=W.mReadBytes(W.MagRegs.OUT_X_L_M, 6);
//autocalc  0=raw, 1=raw-offset, 2 Gauss  
  var autocalc=2;
M=useCalibration(magcal.scale8,autocalc,m);
console.log(" "+M[0]+","+M[1]+","+M[2]); //raw
}//endif
}//end displayMag

Listing the scales

function showscales(){
for(var x in magcal)console.log(x);
}

An Output Sample

>
=undefined
AG replied 104
M replied 61
do a reset of AG
AG SWreset= 0
reset the magnetometer
scale4
scale8
scale12
scale16
 -0.00014387969,-0.09589182669,-0.20146481881
 0.00023358480,-0.09475134273,-0.20193948954
 -0.00110189705,-0.09552740429,-0.20038360033
 0.00167522343,-0.09481362313,-0.19971340522
 0.00177061744,-0.09662211209,-0.20106377922
 0.00193627169,-0.09344444901,-0.20128787409
 0.00032607760,-0.09668255780,-0.20133741284
 0.00229249432,-0.09388396965,-0.20384650603

---

Attachments:

• Magtest1.js

[espruino-discuss2]

Posted at 2017-05-10 by ClearMemory041063

Code to Read the Gyroscope and Accelerometer Using the FIFO

The Gyroscope ODR (Output Data Rate) Also Controls the Accelerometer ODR if it is On.

/*
ODR_G 
Gyroscope output data rate selection. Default value: 000
Table 46
| Value | ODR [Hz] | Cutoff [Hz] |
| --- | --- | --- |
| 0 | Power-down | n.a. |
| 1 | 14.9 | 5 |
| 2 | 59.5 | 19 |
| 3 | 119 | 38 |
| 4 | 238 | 76 |
| 5 | 476 | 100 |
| 6 | 952 | 100 |
| 7 | n.a. | n.a.|
*/
W.AGwrite(W.REGval.ODR_G,0);

By setting it to 0 (Off) the Accelerometer is controlled by

/*
ODR_XL 
Accelerometer Output data rate and power mode selection. default value: 000 
###### Table 68
| ODR_XL | ODR selection [Hz] |
| --- | --- |
| 0 | Power-down |
| 1 | 10 Hz |
| 2 | 50 Hz |
| 3 | 119 Hz |
| 4 | 238 Hz |
| 5 | 476 Hz |
| 6 | 952 Hz |
| 7 | n.a. |
*/
W.AGwrite(W.REGval.ODR_XL,2);

Producing this output:

Alength= 30
A=, -455,-1526,16800
A=, -715,-1489,16801
A=, -595,-1488,16801
A=, -593,-1497,16854
A=, -757,-1442,16755
A=, -527,-1473,16816
A=, -623,-1513,16852
A=, -736,-1483,16771
A=, -511,-1495,16811
A=, -679,-1517,16867
>clearInterval();

Changing the gyro ODR to non zero

W.AGwrite(W.REGval.ODR_G,1);

Produces this output:

Alength= 18
G=, -741,206,-16, A=, -715,-1464,16811
G=, -738,200,-19, A=, -787,-1478,16819
G=, -734,197,-23, A=, -755,-1489,16795
Alength= 18
G=, -737,199,-20, A=, -854,-1499,16796
G=, -740,201,-17, A=, -829,-1453,16775
G=, -727,198,-17, A=, -788,-1484,16802
>clearInterval();

Some Notes

G is Gyro X,Y ,and Z raw counts. A= Accelerometer X,Y, and Z raw counts.
Note a new version of LSM9DS1.js is attached and the test program AGtest1.js
The LSM9DS1.js goes in the modules subdirectory of your WebIDE project.
The data are read every 200 ms, determined by a set interval.
The ODR and the interval interact. At low ODR fewer samples are in the FIFO in a 200 ms interval.
The FIFO can contain up to 32 samples and can be set to fewer samples if needed.

---

Attachments:

• AGtest1.js
• LSM9DS1.js

[gfwilliams]

Posted at 2017-05-11 by @gfwilliams

Thanks for posting this! There's an internal FIFO? That could really help with power efficiency in some devices - in Puck.js for instance I have to wake it up every time a reading is received. It'd be great to be able to wake up only every so often and drain the FIFO.

[espruino-discuss2]

Posted at 2017-05-11 by ClearMemory041063

@gordon
The Accelerometer, Temperature and Gyroscope use the FIFO, the magnetometer is not included in the FIFO. One interrupt mode is based on the number of samples in the FIFO.
My Sparkfun breakout board didn't bring the interrupt pins to a header. There are also some low power modes as well to explore.

[espruino-discuss2]

Posted at 2017-05-12 by ClearMemory041063

Accelerometer/Gyroscope Bits

Used as input to AGread and AGwrite functions.

General Control Bits

BOOT

Reboot memory content. Default value: 0 (0: normal mode; 1: reboot memory content)

1. Boot request is executed as soon as internal oscillator is turned-on. It is possible to set bit while in powerdown
   mode, in this case it will be served at the next normal mode or sleep mode.

BDU

Block data update. Default value: 0 (0: continuous update; 1: output registers not updated until MSB and LSB read)

H_LACTIVE

Interrupt activation level. Default value: 0
(0: interrupt output pins active high; 1: interrupt output pins active low)

PP_OD

Push-pull/open-drain selection on the INT1_A/G pin and INT2_A/G pin.
Default value: 0
(0: push-pull mode; 1: open-drain mode)

SIM

SPI serial interface mode selection. Default value: 0
(0: 4-wire interface; 1: 3-wire interface).

IF_ADD_INC

Register address automatically incremented during a multiple byte access with a
serial interface (I2C or SPI). Default value: 1
(0: disabled; 1: enabled)

BLE

Big/Little Endian data selection. Default value 0
(0: data LSB @ lower address; 1: data MSB @ lower address)

SW_RESET

Software reset. Default value: 0
(0: normal mode; 1: reset device)
This bit is cleared by hardware after next flash boot.

DRDY_mask_bit

Data available enable bit. Default value: 0
(0: DA timer disabled; 1: DA timer enabled)

I2C_DISABLE

Disable I2C interface. Default value: 0
(0: both I2C and SPI enabled; 1: I2C disabled, SPI only)

ST_G

Angular rate sensor self-test enable. Default value: 0
(0: Self-test disabled; 1: Self-test enabled)

ST_XL

Linear acceleration sensor self-test enable. Default value: 0
(0: Self-test disabled; 1: Self-test enabled)

Gyro Configuration Bits

SLEEPG

Gyroscope sleep mode enable. Default value: 0
(0: disabled; 1: enabled)

ODR_G

Gyroscope output data rate selection. Default value: 000

Table 46

Value	ODR [Hz]	Cutoff [Hz]
0	Power-down	n.a.
1	14.9	5
2	59.5	19
3	119	38
4	238	76
5	476	100
6	952	100
7	n.a.	n.a.

Table 47.

ODR_G [2:0]	BW_G [1:0]	ODR [Hz]	Cutoff [Hz]
0	0	Power-down	n.a.
0	1	Power-down	n.a.
0	2	Power-down	n.a.
0	3	Power-down	n.a
1	0	14.9	n.a.
1	1	14.9	n.a.
1	2	14.9	n.a.
1	3	14.9	n.a.
2	0	59.5	16
2	1	59.5	16
2	2	59.5	16
2	3	59.5	16
3	0	119	14
3	1	119	31
3	2	119	31
3	3	119	31
4	0	238	14
4	1	238	29
4	2	238	63
4	3	238	78
5	0	476	21
5	1	476	28
5	2	476	57
5	3	476	100
6	0	952	33
6	1	952	40
6	2	952	58
6	3	952	100
7	0	n.a.	n.a.
7	1	n.a.	n.a.
7	2	n.a.	n.a.
7	3	n.a.	n.a.
ODR_G [2:0] are used to set ODR selection when both the accelerometer and gyroscope
are activated. BW_G [1:0] are used to set gyroscope bandwidth selection.

FS_G

Gyroscope full-scale selection. Default value: 00
(00: 245 dps; 01: 500 dps; 10: Not Available; 11: 2000 dps)

BW_G

Gyroscope bandwidth selection. Default value: 00
ODR_G [2:0] are used to set ODR selection when both the accelerometer and gyroscope
are activated. BW_G [1:0] are used to set gyroscope bandwidth selection.

G_INT_SEL

INT selection configuration. Default value: 00 (Refer to Figure 28)

G_OUT_SEL

Out selection configuration. Default value: 00 (Refer to Figure 28)

G_LP_mode

Low-power mode enable. Default value: 0
(0: Low-power disabled; 1: Low-power enabled)

G_HP_EN

High-pass filter enable. Default value: 0
(0: HPF disabled; 1: HPF enabled, refer to Figure 28)

HPCF_G

Gyroscope high-pass filter cutoff frequency selection. Default value: 0000

Table 52

HPCF_G [3:0]	ODR= 14.9 Hz	ODR= 59.5 Hz	ODR= 119 Hz	ODR= 238 Hz	ODR= 476 Hz	ODR= 952 Hz
0	1	4	8	15	30	57
1	0.5	2	4	8	15	30
2	0.2	1	2	4	8	15
3	0.1	0.5	1	2	4	8
4	0.05	0.2	0.5	1	2	4
5	0.02	0.1	0.2	0.5	1	2
6	0.01	0.05	0.1	0.2	0.5	1
7	0.005	0.02	0.05	0.1	0.2	0.5
8	0.002	0.01	0.02	0.05	0.1	0.2
9	0.001	0.005	0.01	0.02	0.05	0.1

SignX_G

Pitch axis (X) angular rate sign. Default value: 0
(0: positive sign; 1: negative sign)

SignY_G

Roll axis (Y) angular rate sign. Default value: 0
(0: positive sign; 1: negative sign)

SignZ_G

Yaw axis (Z) angular rate sign. Default value: 0
(0: positive sign; 1: negative sign)

Orient_G

Directional user orientation selection. Default value: 000

REF_G

Reference value for gyroscope’s digital high-pass filter (r/w).
Default value: 0000 0000

Accelerometer Bits

Dec_XL

Decimation of acceleration data on OUT REG and FIFO. Default value: 00
(00: no decimation;
01: update every 2 samples;
10: update every 4 samples;
11: update every 8 samples)

Zen_XL

Accelerometer’s Z-axis output enable. Default value: 1
(0: Z-axis output disabled; 1: Z-axis output enabled)

Yen_XL

Accelerometer’s Y-axis output enable. Default value: 1
(0: Y-axis output disabled; 1: Y-axis output enabled)

Xen_XL

Accelerometer’s X-axis output enable. Default value: 1
(0: X-axis output disabled; 1: X-axis output enabled)

ODR_XL

Output data rate and power mode selection. default value: 000

Table 68

ODR_XL	ODR selection [Hz]
0	Power-down
1	10 Hz
2	50 Hz
3	119 Hz
4	238 Hz
5	476 Hz
6	952 Hz
7	n.a.

FS_XL

Accelerometer full-scale selection. Default value: 00
(00: ±2g; 01: ±16 g; 10: ±4 g; 11: ±8 g)

BW_SCAL_ODR_XL

Bandwidth selection. Default value: 0
(0: bandwidth determined by ODR selection:

• BW = 408 Hz when ODR = 952 Hz, 50 Hz, 10 Hz;
• BW = 211 Hz when ODR = 476 Hz;
• BW = 105 Hz when ODR = 238 Hz;
• BW = 50 Hz when ODR = 119 Hz;
  1: bandwidth selected according to BW_XL [2:1] selection)

BW_XL

Anti-aliasing filter bandwidth selection. Default value: 00
(00: 408 Hz; 01: 211 Hz; 10: 105 Hz; 11: 50 Hz)

HR_XL

High resolution mode for accelerometer enable. Default value: 0
(0: disabled; 1: enabled).

Table 71

HR	CTRL_REG7 (DCF [1:0])	LP cutoff freq. [Hz]
1	0	ODR/50
1 } 1	ODR/100
1	2	ODR/9
1	3	ODR/400

DCF_XL

Accelerometer digital filter (high pass and low pass) cutoff frequency selection: the bandwidth
of the high-pass filter depends on the selected ODR. See Table 71

FDS_XL

Filtered data selection. Default value: 0
(0: internal filter bypassed; 1: data from internal filter sent to output register and FIFO)

HPIS1_XL

High-pass filter enabled for acceleration sensor interrupt function on Interrupt. Default
value: 0 (0: filter bypassed; 1: filter enabled)

Temperature Bits

FIFO_TEMP_EN

Temperature data storage in FIFO enable. Default value: 0
(0: temperature data not stored in FIFO; 1: temperature data stored in FIFO)

FIFO Control Bits

FIFO_EN

FIFO memory enable. Default value: 0
(0: disabled; 1: enabled)

STOP_ON_FTH

Enable FIFO threshold level use. Default value: 0
(0: FIFO depth is not limited; 1: FIFO depth is limited to threshold level)

FIFO_TEMP_EN

Temperature data storage in FIFO enable. Default value: 0
(0: temperature data not stored in FIFO; 1: temperature data stored in FIFO)

FMODE

FIFO mode selection bits. Default value: 000

Table 84

FMODE	Mode
0	Bypass mode. FIFO turned off
1	FIFO mode. Stops collecting data when FIFO is full.
2	Reserved
3	Continuous mode until trigger is deasserted, then FIFO mode
4	Bypass mode until trigger is deasserted, then Continuous mode.
6	Continuous mode. If the FIFOis full, the new sample overwrites the older sample.
5	No specification
7	No specification

FTH

FIFO threshold level setting. Default value: 0 0000

FIFO Status

FTHstatus

FIFO threshold status.
(0: FIFO filling is lower than threshold level; 1: FIFO filling is equal or higher than
threshold level

OVRN 0

FIFO overrun status.
(0: FIFO is not completely filled; 1: FIFO is completely filled and at least one samples
has been overwritten)

FSS 0

Number of unread samples stored into FIFO.
(000000: FIFO empty; 100000: FIFO full, 32 unread samples)
Table 87. FIFO_SRC example: OVR/FSS details

FTH	OVRN	FSS5	FSS4	FSS3	FSS2	FSS1	FSS0	Description
0	0	0	0	0	0	0	0	FIFO empty
x	0	0	0	0	0	0	1	1
x		0	1	0	0	0	0	0
1	1	1	0	0	0	0	0	At least one sample has been overwritten

Interrupt Control Bits

SLEEP_ON_INACT_EN

Gyroscope operating mode during inactivity. Default value: 0
(0: gyroscope in power-down; 1: gyroscope in sleep mode)

ACT_THS

Inactivity threshold. Default value: 000 0000

ACT_DUR

Inactivity duration. Default value: 0000 0000

AOI_XL

AND/OR combination of accelerometer’s interrupt events. Default value: 0
(0: OR combination; 1: AND combination)

D6

6-direction detection function for interrupt. Default value: 0
(0: disabled; 1: enabled)

ZHIE_XL

Enable interrupt generation on accelerometer’s Z-axis high event. Default value: 0
(0: disable interrupt request; 1: interrupt request on measured acceleration value
higher than preset threshold)

ZLIE_XL

Enable interrupt generation on accelerometer’s Z-axis low event. Default value: 0
(0: disable interrupt request; 1: interrupt request on measured acceleration value
lower than preset threshold)

YHIE_XL

Enable interrupt generation on accelerometer’s Y-axis high event. Default value: 0
(0: disable interrupt request; 1: interrupt request on measured acceleration value
higher than preset threshold)

YLIE_XL

Enable interrupt generation on accelerometer’s Y-axis low event. Default value: 0
(0: disable interrupt request; 1: interrupt request on measured acceleration value
lower than preset threshold)

XHIE_XL

Enable interrupt generation on accelerometer’s X-axis high event. Default value: 0
(0: disable interrupt request; 1: interrupt request on measured acceleration value
higher than preset threshold)

XLIE_XL

Enable interrupt generation on accelerometer’s X-axis low event. Default value: 0
(0: disable interrupt request; 1: interrupt request on measured acceleration value
lower than preset threshold)

THS_XL_X

X-axis interrupt threshold. Default value: 0000 0000

THS_XL_Y

Y-axis interrupt threshold. Default value: 0000 0000

THS_XL_Z

Z-axis interrupt threshold. Default value: 0000 0000

WAIT_XL

Wait function enabled on duration counter. Default value: 0
(0: wait function off; 1: wait for DUR_XL [6:0] samples before exiting interrupt)

DUR_XL6

Enter/exit interrupt duration value. Default value: 000 0000

INT1_IG_G

Gyroscope interrupt enable on INT 1_A/G pin. Default value: 0
(0: disabled; 1: enabled)

INT1_IG_XL

Accelerometer interrupt generator on INT 1_A/G pin. Default value: 0
(0: disabled; 1: enabled)

INT1_FSS5

FSS5 interrupt enable on INT 1_A/G pin. Default value: 0
(0: disabled; 1: enabled)

INT1_OVR

Overrun interrupt on INT 1_A/G pin. Default value: 0
(0: disabled; 1: enabled)

INT1_FTH

FIFO threshold interrupt on INT 1_A/G pin. Default value: 0
(0: disabled; 1: enabled)

INT1_Boot

Boot status available on INT 1_A/G pin. Default value: 0
(0: disabled; 1: enabled)

INT1_DRDY_G

Gyroscope data ready on INT 1_A/G pin. Default value: 0
(0: disabled; 1: enabled)

INT1_DRDY_XL

Accelerometer data ready on INT 1_A/G pin. Default value: 0
(0: disabled; 1: enabled)

INT2_INACT

Inactivity interrupt output signal. Default value: 0
(0: no interrupt has been generated; 1: one or more interrupt events have been
generated)

INT2_FSS5

FSS5 interrupt enable on INT2_A/G pin. Default value: 0
(0: disabled; 1: enabled)

INT2_OVR

Overrun interrupt on INT2_A/G pin. Default value: 0
(0: disabled; 1: enabled)

INT2_FTH

FIFO threshold interrupt on INT2_A/G pin. Default value: 0
(0: disabled; 1: enabled)

INT2_DRDY_TEMP

Temperature data ready on INT2_A/G pin. Default value: 0
(0: disabled; 1: enabled)

INT2_DRDY_G

Gyroscope data ready on INT2_A/G pin. Default value: 0
(0: disabled; 1: enabled)

INT2_DRDY_XL

Accelerometer data ready on INT2_A/G pin. Default value: 0
(0: disabled; 1: enabled)
//Status registers
Xxxxxxxxxxxxxxxxxxxxx

IG_XL 0, IG_XL2 0

Accelerometer interrupt output signal. Default value: 0
(0: no interrupt has been generated; 1: one or more interrupt events have been generated)

IG_G 0, IG_G2 0

Gyroscope interrupt output signal. Default value: 0
(0: no interrupt has been generated; 1: one or more interrupt events have been generated

INACT 0, INACT2 0

Inactivity interrupt output signal. Default value: 0
(0: no interrupt has been generated; 1: one or more interrupt events have been generated)

BOOT_STATUS 0, BOOT_STATUS2 0

Boot running flag signal. Default value: 0
(0: no boot running; 1: boot running)

TDA 0, TDA2 0

Temperature sensor new data available. Default value: 0
(0: new data is not yet available; 1: new data is available)

GDA 0, GDA2 0

Gyroscope new data available. Default value: 0
(0: a new set of data is not yet available; 1: a new set of data is available)

XLDA 0, XLDA2 0

Accelerometer new data available. Default value: 0
(0: a new set of data is not yet available; 1: a new set of data is available)

IA_G

Gyro Interrupt active. Default value: 0
(0: no interrupt has been generated; 1: one or more interrupts have been generated)

ZH_G

Gyro Yaw (Z) high. Default value: 0
(0: no interrupt, 1: Z high event has occurred)

ZL_G

Gyro Yaw (Z) low. Default value: 0
(0: no interrupt; 1: Z low event has occurred)

YH_G

Gyro Roll (Y) high. Default value: 0
(0: no interrupt, 1: Y high event has occurred)

YL_G

Gyro Roll (Y) low. Default value: 0
(0: no interrupt, 1: Y low event has occurred)

XH_G

Gyro Pitch (X) high. Default value: 0
(0: no interrupt, 1: X high event has occurred)

XL_G

Gyro Pitch (X) low. Default value: 0
(0: no interrupt, 1: X low event has occurred)

IA_XL

Accelerometer Interrupt active. Default value: 0.
(0: no interrupt has been generated; 1: one or more interrupts have been generated)

ZH_XL

Accelerometer's Z high event. Default value: 0
(0: no interrupt, 1: Z high event has occurred)

ZL_XL

Accelerometer's Z low event. Default value: 0
(0: no interrupt; 1: Z low event has occurred)

YH_XL

Accelerometer's Y high event. Default value: 0
(0: no interrupt, 1: Y high event has occurred)

YL_XL

Accelerometer's Y low event. Default value: 0
(0: no interrupt, 1: Y low event has occurred)

XH_XL

Accelerometer's X high event. Default value: 0
(0: no interrupt, 1: X high event has occurred)

XL_XL

Accelerometer's X low. event. Default value: 0
(0: no interrupt, 1: X low event has occurred)

Latest version of the LSM9DS1.js module is attached.

If you need a way to cool your coffee or tea and need to stretch here is a different kind of project.
https://www.youtube.com/watch?v=5_50RuMcc28

Attachments:

• LSM9DS1.js

[espruino-discuss2]

Posted at 2017-05-15 by ClearMemory041063

Calibrating the Accelerometer

The procedure is similar to the magnetometer calibration but several things are done differently.

1. There are 3 axis, and if the accelerometer is attached to one face of a cube, we need to collect data with each of the six faces of the cube on the bottom. Data taken when the sensor is in motion may contain additional acceleration values that would distort the calibration.
2. The magnetometer used the average R value, for the accelerometer we will calculate the counts needed to produce a 1G value, taking the range setting of the accelerometer as a factor.

We need a way to signal the program that the sensor is positioned and ready to acquire some data.

With WebIDE this can be achieved by reassigning the console with the setConsole() function.
With a PICO this has its perils if you set the program up to run on boot and save the program.
You need to provide a way to get the console back to the USB port. Preferably several ways!

//ConsoleMenu.js 11 May 2017

//How not to brick a PICO when reassigning the console
// away from the USB port to do menu programs
//Setup the button to light the LED and reset the Pico
//Always include this code when a save() and oninit() functions are // used.
setWatch(function(e) {
  digitalWrite(LED1, e.state);
  USB.setConsole();
  reset();
}, BTN, { repeat: true });

E.on('init', function() {
 console.log("Hello");
 startPgm();
});
//input cmd from terminal,send it to parsecmd()
var sst=""; //The input buffer
USB.on('data', function (data) {
 var i;
  sst+=data;
// look for control c in input stream
  if(sst.indexOf(String.fromCharCode(3))>-1){
  USB.setConsole();
  reset();
  }//   console.log("control C seen");
  USB.print(data);
  if(sst.length>-1)
  if(sst.charAt(sst.length-1)==="\r")selectparser();
});

//Espruino replies here
LoopbackA.on('data',function(data){
  USB.print(data); //sending data to terminal
});
console.log("In left pane type startPgm();");
console.log("Use startPgm() first and make sure you can exit back to the console");
console.log("Once you are sure that a proper exit works then type  save();");

var menulevel=0;
function startPgm(){
setTimeout(function () {
// start();
 LoopbackB.setConsole();
 mainmenu();
}, 1000);
}//end startPgm

function mainmenu(){
 USB.print("\n\rMain Menu\n\rType somthing or a control C to Exit\n\r");
//    USB.setConsole();
}//end mainmenu

function selectparser(){
 USB.print("\n\r"+sst+"\n\r");
//    USB.setConsole();
  
}//end select parser

The attached file CollectAGdata.js combines the above menu program with AGtest1.js to produce a program that collects 32 samples and wait for a carriage return. The sensor can be repositioned and the next setting can be collected by pressing return. When finished type any character followed by a return to exit the program. The data are then copied from the WebIDE left pane and pasted nto a .CSV file. Some example output:

G=, -716,194,-17, A=, -148,-780,16899
G=, -711,193,-18, A=, -154,-787,16901
G=, -718,190,-18, A=, -156,-781,16944
G=, -719,193,-14, A=, -169,-762,16929
G=, -714,194,-12, A=, -178,-765,16942
G=, -714,194,-18, A=, -186,-730,16940
G=, -716,190,-17, A=, -195,-737,16940
G=, -725,191,-17, A=, -210,-736,16887
G=, -711,187,-15, A=, -182,-746,16924
G=, -713,190,-19, A=, -225,-741,16894
G=, -712,192,-21, A=, -209,-760,16893
G=, -704,194,-12, A=, -197,-743,16876
G=, -719,198,-15, A=, -132,-754,16905
G=, -717,217,-15, A=, -145,-706,16794
G=, -713,184,-15, A=, -207,-902,16881
G=, -718,204,-25, A=, -185,-817,16879
G=, -722,193,-9, A=, -110,-743,16895
G=, -721,196,-28, A=, -244,-878,16873
G=, -735,190,-14, A=, -189,-795,16896
G=, -720,214,-21, A=, -179,-749,16898
G=, -714,176,-18, A=, -219,-867,16894
G=, -726,199,-26, A=, -142,-731,16935
G=, -730,190,-18, A=, -156,-772,16936
G=, -719,190,-26, A=, -196,-758,16898
G=, -714,188,-20, A=, -129,-745,16981
G=, -719,193,-26, A=, -203,-777,16936
G=, -726,182,-19, A=, -210,-741,16947
G=, -723,199,-24, A=, -232,-722,16910
G=, -735,187,-27, A=, -149,-738,16921
G=, -729,188,-30, A=, -231,-760,16885
G=, -723,190,-23, A=, -167,-756,16869
G=, -715,192,-21, A=, -221,-760,17003
<- LoopbackB
-> USB

The data are then pasted in a spreadsheet similar to the one used for the magnetometer and the twelve calibration values are calculated.

---

Attachments:

• cal.csv
• CollectAgdata.js

[espruino-discuss2]

Posted at 2017-05-16 by ClearMemory041063

The Accelerometer and Gyroscope Calibrations

Accelerometer May12 2017 2g scale using average R

Culled Range = 2230.842

	Offset	A	B	C
X	-987.2736361	0.995549457	0.140149893	2.11449E-05
Y	272.0992136	-0.042589517	0.991729217	0.00020329
Z	446.896968	-0.24363696	-0.291923385	1

Accelerometer May12 2017 2g scale using target value

Culled Range = 2159.087

	Offset	A	B	C
X	-1068.093899	0.981090704	0.127644011	4.11128E-05
Y	185.8088179	-0.013882693	0.989541404	3.62454E-05
Z	193.6596862	-0.268744893	-0.20999626	1

Gyroscope May12 2017 245deg per s.

Offsets Only as I’m not set up to spin the sensor and collect data.
Culled Range = 2506.073

	Offset	A	B	C
X	-780.9157638	1	0	0
Y	214.1401801	0	1	0
Z	-0.657364084	0	0	1

See attached files

---

Attachments:

• Accel2g12May2017a.ods
• Accel2gMay122017.ods
• gyro245_12May2017.ods

[espruino-discuss2]

Posted at 2017-05-19 by ClearMemory041063

AGmagtest1.js

The attached program AGmagtest.js uses the LSM9DS1.js module and the preceding calibrations to produce data in engineering units.

The variable autocalc controls the type of units displayed.

//autocalc 0=raw, 1=raw-offset, 2 Engineering Units
var autocalc=2;

In the function setupAG() the gyro ODR determines if gyro data are available.

W.AGwrite(W.REGval.ODR_G,1);//do gyro and acceleration
//W.AGwrite(W.REGval.ODR_G,0);//do acceleration only.

Here is sample output with autocalc=2 and ODR_G=1

M magnetometer values are in Gauss,
G gyroscope values are in degrees per second
A acceleration values are in g, (1= Earth gravity)

M,0.0150,-0.0847,-0.1949,G,0.3582,-0.1057,-0.1222,A,0.0839,-0.0478,0.9993,
M,0.0172,-0.0830,-0.1933,G,0.3358,-0.1581,-0.1297,A,0.0869,-0.0552,1.0039,
M,0.0172,-0.0830,-0.1933,G,0.3433,-0.1655,-0.1297,A,0.0841,-0.0479,1.0000,
M,0.0172,-0.0830,-0.1933,G,0.3807,-0.1057,-0.1222,A,0.0831,-0.0438,0.9987,
M,0.0151,-0.0866,-0.1965,G,0.4031,-0.2104,-0.1222,A,0.0817,-0.0398,0.9956,
M,0.0151,-0.0866,-0.1965,G,0.3807,-0.0833,-0.1222,A,0.0821,-0.0416,0.9960,
M,0.0151,-0.0866,-0.1965,G,0.4031,-0.1879,-0.1147,A,0.0831,-0.0460,0.9991,
M,0.0162,-0.0845,-0.1933,G,0.3732,-0.0982,-0.1446,A,0.0822,-0.0459,1.0009,
M,0.0162,-0.0845,-0.1933,G,0.3059,-0.1132,-0.1297,A,0.0834,-0.0461,1.0031,
>clearInterval();

Changing ODR_G to 0 produces:

M,0.0154,-0.0826,-0.1849,A,0.0864,-0.0516,1.0014,
M,0.0154,-0.0826,-0.1849,A,0.0868,-0.0537,1.0017,
M,0.0154,-0.0826,-0.1849,A,0.0858,-0.0549,1.0009,
M,0.0154,-0.0826,-0.1849,A,0.0862,-0.0567,1.0032,
M,0.0154,-0.0826,-0.1849,A,0.0861,-0.0594,1.0028,
M,0.0154,-0.0826,-0.1849,A,0.0852,-0.0598,1.0009,
M,0.0154,-0.0826,-0.1849,A,0.0883,-0.0601,0.9992,
M,0.0154,-0.0826,-0.1849,A,0.0877,-0.0574,0.9964,
>clearInterval();

---

Attachments:

• AGMagtest1.js

[espruino-discuss2]

Posted at 2017-05-19 by @allObjects

...I expected you to put the sensor onto the stirling engine fly wheel... a centered / balanced puck and sensor would work to measure the RPM. ;-)

[espruino-discuss2]

Posted at 2017-05-20 by ClearMemory041063

Now that's an interesting idea. The flywheel shaft is 10mm long with a crank on each end, so there's not much room for the Puck. Perhaps a photo interrupter with a tab on the flywheel would be easier for RPM sensing.
The LTD (Low Temperature Differential) Stirling is right up against the wall to work using hot coffee and small design changes can move the needed temperature differential.
One idea to pursue is a pressure sensor tapped into the displacer chamber. This would allow one to study the differences in displacer designs such as size, materials and motion of the displacer.

[espruino-discuss2]

Posted at 2017-05-20 by ClearMemory041063

Correction to AGMagtest1

The index values were corrected in the displayAg() function when set to display Accelerometer and Magnetometer values. AGMagtest2.js is attached.

Adding the Rodrigues.js module to level the compass

The background for this module is described here:
http://forum.espruino.com/conversations/298151/

The basic idea is to take the accelerometer readings and determine the vector transformation needed to level the compass. This is done with the function A=FF.Setup(AA,[0,0,1]); where FF is an instance of Rodrigues. The tilt angle theta is then available and subsequent calls to the function BB=FF.RotVector(t) will transform other vectors (magnetometer) into level coordinates.
The attached Rodrigues.js should be placed in the modules subdirectory of your WebIDE project.
The attached program AGMagCompass1.js will then produce the following output when autocalc=2 and W.AGwrite(W.REGval.ODR_G,1);//do gyro and acceleration.

M,0.0744,-0.1211,-0.1714,G,-0.1053,0.0413,-0.0948,A,0.1575,0.3104,0.8621,
Tilt,21.98781027298,Heading,306.68106708380,Dip,72.16684715533
M,0.0735,-0.1221,-0.1734,G,-0.1128,0.0563,-0.1072,A,0.1559,0.3118,0.8613,
Tilt,22.03654082060,Heading,306.02287887278,Dip,72.48561573888
M,0.0730,-0.1207,-0.1713,G,-0.1165,0.0251,-0.0998,A,0.1551,0.3114,0.8618,
Tilt,21.98386692289,Heading,306.35699288042,Dip,72.36622200953
M,0.0742,-0.1194,-0.1707,G,-0.0928,0.0712,-0.0823,A,0.1538,0.3145,0.8604,
Tilt,22.14296350951,Heading,308.33309975404,Dip,72.42224117781
M,0.0736,-0.1171,-0.1704,G,-0.0679,0.0313,-0.0674,A,0.1558,0.3134,0.8606,
Tilt,22.13447453002,Heading,308.75984729535,Dip,72.83761339423
>clearInterval();

Changing W.AGwrite(W.REGval.ODR_G,0);//do acceleration only produces the following output:

M,0.0747,-0.1202,-0.1713,A,0.1563,0.3096,0.8569,
Tilt,22.03355580117,Heading,307.43511787449,Dip,72.28617992890
M,0.0763,-0.1235,-0.1719,A,0.1563,0.3094,0.8568,
Tilt,22.02918941321,Heading,306.91511852880,Dip,71.66990038608
M,0.0741,-0.1204,-0.1721,A,0.1560,0.3093,0.8569,
Tilt,22.01028842165,Heading,306.98156662314,Dip,72.44988041050
M,0.0780,-0.1226,-0.1704,A,0.1559,0.3090,0.8568,
Tilt,22.00089649394,Heading,308.38042963598,Dip,71.31936469986
>clearInterval();

--------------------------------------------
**Attachments:**

* [AGMagCompass1.js](https://www.espruino.com/forumattachments/7c8f25598490c94f4217ddfdf931fc49b8401656.js)
* [AGMagtest2.js](https://www.espruino.com/forumattachments/7eb6f59768e9ea5367ea8ec12f392bf485473382.js)
* [Rodrigues.js](https://www.espruino.com/forumattachments/c114a07ee409ed6b57c9c7e77f69d8dc82d37c9f.js)

[espruino-discuss2]

Posted at 2017-05-21 by @allObjects

Why would you use a .connect() function / method to create a Rodrigues instance?

I know hat this pattern is typical for connecting devices. But in this case, it is just a transformer, isn't?

To return a constructor function in a require, just set the exported object to it: exports = Rodrigues;.

If you want to stick with the pattern, you can return exports.getInstance = function() { return new Rodrigues(); } to provide a self documenting function.

[espruino-discuss2]

Posted at 2017-05-23 by ClearMemory041063

Thanks for the input @allObjects
Your expertise in JavaScript is greatly appreciated.
As with all projects and programming each author brings to the task a collection of familiarity with subjects and blind spots to other subjects. As a project develops new knowledge is revealed as ignorance retreats.
So your input has led me to search for more information on modules.
The CommonJS paradigm expressed in the following link seems to fit the pattern you are proposing for the Rodrigues.js module.
https://medium.freecodecamp.com/javascript-modules-a-beginner-s-guide-783f7d7a5fcc
So far I haven’t found a reference (other than Espruino) to the methods used for hardware module using the Connect method.
That which I knew of JavaScript was obtained from using it in HTML and using Espruino. The opposite problem seems to show up in this @trusktr
question.
http://forum.espruino.com/conversations/305040/