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Sensetile (STEVAL-STLKT01V1) -- How to configure (modify the setup of) acc, gyro and mag and interpret the collected data from these sensor

jin lu
Associate II
Posted on July 16, 2018 at 21:05

I  am working with the datalog application of the sensortile evaluation kit.  I can see the data collected from the  the acc (LSM303AGR), gyro(LSM6DSM), and mag(LSM303AGR).  I have read the data sheet of these sensors,  but still have no idea about how to interpret the data.  In particular,  I have the following questions (by the way, I asked the same questions to support and had not got any response for more than a week.): 

(1)  acc and gyro data:   How do I interpret the acc and gyro data in terms of the units (g for acc,  degree/sec for gyro).  For example, one sample data I got  is

acc = {axis_x, axis_y, axis_z} = { 80, 144, 993},

gyro = {axis_x, axis_y, axis_z} = {-280, 3150, -1050}

How do I translate that in terms of g and d/s?  

(2) mag data:  I am not clear how to interpret the data in terms of the direction of motion with respect of the north pole (that was my understanding of a e-compass).

For example,

mag = {axis_x, axis_y, axis_z} = {244, 189, -648}

I have no idea how to read the data.     

(3) x, y, z axis  of the data:  Suppose I put the board  (and sensor) facing up,  I assume the z-axis is vertical to the earth and points up,  x-axis and y-axis is  parallel to the earth. But  which direction is x and which direction is y? 

(4) In  sensortile_accelero.c,  have some questions about the following APIs  

BSP_ACCELERO_SET_FS

BSP_ACCELERO_SET_ODR

---- I do not see them being called for datalog application (only accelerometer  init and enable  are called).   How are they (full scale, sample, rate ) set, then?  Maybe there is a default setup for full scale and data rate?   The reason I am asking is if I want know how  to change the full scale and data rate.

BSP_ACCELERO_SET_AXIS_STATUS,  

----I looked and the code, it says 'Set the enabled/disabled status of the accelerometer sensor axes',

what is the 'status'  of  an axis?  

BSP_ACCELERO_Get_6D_Orientation_XH_Ext  (and XL, YH, YL,....)

---  the code says:   Get the 6D orientation XH axis.   What does 'Orientation' mean here.   How do I interpret the data from the APS,  can you give me an example?  

BSP_ACCELERO_Get_Sensitivity

---- What does the 'sensitivity' mean here

Thanks in advance for your help.   A good tech note with examples would be greatly appreciated.   

Jin

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2 REPLIES 2
T J
Lead
Posted on July 17, 2018 at 02:01

I will be working on similar chips next week... LIS3D and LIS3M

We can work together from there...

did you find any App notes ?

surely there is some guidelines in the acc (LSM303AGR), gyro(LSM6DSM), and mag(LSM303AGR) data sheets ?

they should indicate an app note.

jin lu
Associate II
Posted on July 17, 2018 at 03:07

T. J,

Thanks for your response. I did find app notes for the two chips. Let me know if you need them. But they did not say too much from a programmer's point of view. I had to read the reference driver code to understand how the chips are configured. I am curious what applications you intend to use these chips. Thanks.

Jin