Calibration of the accelerometer

[robypez]

Hello. I'm starting my "leveler" app and everything works fine.

I'm obtaining from the accelerometer some raw data from X, Y and Z axes, but they are not "0" of course: they change in a fixed interval. I want to set a reference (calibration), maybe using the red button on the SensorTag, and then I want to convert the raw data in roll and pitch degree.

Someone has something ready (maybe a library with some helpers)?
Is possibile to save the three calibration value on the tag? Is there a small memory storage available to use?

[ardiri]

the sensor tag is designed to provide a number of sensor information that can be accessible over low energy bluetooth (BLE); it doesn't have the capacity to actually implement your own firmware (at this point) where you can do more than what it currently does right now. if you want to process the data; you should consider pairing up with a mobile application - like we have already setup for you as an example with the TI Sensors example.

you can then store values in response to a user interaction from the mobile application (ie: have a button called CALIBRATE) which stores the x,y,z accelerometer values into a JavaScript variable. once you have this; you can then simply listen for notifications on the accelerometer and then implement calculations to calculate the pitch and roll of the device.

http://physics.rutgers.edu/~aatish/teac ... kshop3.pdf

there is a great explanation of how to calculate such values from the raw data of the accelerometer - if you google a little more; you may even find a library in JavaScript which you can use directly within your Evothings application. let us know how you come along; it would be great to expand our examples - we do accept submissions to our github repository!