Sensors sensitivity (like G-range)

Issue #84 invalid
Romain Tchakamian created an issue

Hi all, not sure if this issue belongs here, anyway:

With the API there is a way to get G-range with the following code :

mMds.builder().build(this).get("suunto://" + connectedSerial + "/Meas/Acc/Config", null, new MdsResponseListener() {
  public void onSuccess(String data, MdsHeader header) {

  public void onError(MdsException var1) {
     /* error handler */

I get Grange = 8.

When I look at the accelerometer+gyroscope datasheet (Section 4.1 Mechanical characteristics p20) :

FS = ±8 => 0.244 mg/LSB = 2.4 (mm/s²)/LSB.

But when I read data from the accelerometer it seems that the conversion is 1 LSB = 1 m/s² (because for z axis the returned value when Movesense is horizontal is 9.8).

So my questions are :

1/ Why is that? Where does the conversion to 1 LSB = 1 m/s² occur?

2/ How can I get the gyroscope FS sensitivity value ? And can I set it?

3/ Is there a documentation concerning the accelerometer/gyroscope/magnetometer axis directions and headings? It seems that each has a different set of axis. And is it possible to change the axis configuration ?

Many thanks!

Comments (2)

  1. Petri Lipponen

    Since this is more like a question than bug, I’m marking this “invalid”. In future, the best place for this kind of questions is the (tag: movesense).

    However here’s the answers to your questions:

    1. The API returns results as floating point numbers with SI units. /Meas/Acc has unit m/s^2. This makes the API independent of sensor hw.
    2. Gyro sensitivity is changed exactly the same as Acc: /Meas/Gyro/Config for get/set current value and /Meas/Gyro/Info for getting a list of possible values
    3. If the does not have axis values they are as follows:
      x-axis: along top of sensor in direction of text/logo
      y-axis; along top of sensor orthogonal to text/logo
      z-axis: out of top of sensor

    Gyro axes are the same, but the value is the rotation around the said axis.

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