BMX055 Accelerometer Calibration

[arwhalley]

This device produces readings in G, but G is not a constant value over the surface of the earth. What value of G, in m/s2, is represented by an output value of unity? Is 1G the value of the earth's gravitational field at the location at which the device is calibrated, or is it calibrated in m/s2 and 1G represents a constant, such as 9.81m/s2?

[o_o]

Hi Sense,

The assumption for the earth's gravity coefficient is 9.81m/s² in terms of sensitivity error. The actual earth's gravity in a specific location does not affect sensitivity error.

For the offset, indeed the local Earth's gravity does have an impact. but this offset is quite limited, about 0.5% (50mg) between the min and max value on Earth. Considering that the 0-g offset after soldering alone is typically +-80mg, without considering other factors such as cross-axis alignment, temperature and mechanical stress.

In general, for applications using accelerometer data only use a simple offset calibration which combines a wide variety of factors that impact the offset, and do not calibrate for sensitivity, cross-axis effect, or temperature.

o_o