New Sensor Parameter Standard

by Kevin Morris

Early this year we took a look at MEMS standards (or the need therefor), and one of the active efforts involved unifying sensor parameters and data sheets so that users could compare and combine different sensors from different companies – a challenging task at present.

Well, that effort has now yielded some results. The “Sensor Performance Parameter Definitions” document has been released under the auspices of the MEMS Industry Group (MIG). The effort itself was led by Intel and Qualcomm, with input from a number of different sensor players.

While many such standards documents start with a limited scope and just can’t stop, a quick look at the table of contents suggests that hasn’t happened here. The bulk of the document is simply a set of definitions for parameters for different sensors. It is augmented by helpful lists of terms and acronyms, symbols and equations, and measurement conversions.

The sensors covered by the document are:

Accelerometers
Magnetometers
Gyroscopes
Pressure Sensors
Humidity Sensors
Temperature Sensors
Ambient Light Sensors
Proximity Sensors

This seems to cover all of the Windows HID-required sensors (since inclinometers and orientation sensors are typically fused versions of the above) except for GPS.

Each sensor type has its own parameters. For example, the following parameters are defined for accelerometers:

Full Scale Range
Digital Bit Depth
Zero-g Offset
Zero-g Offset Temperature Coefficient
Sensitivity
Sensitivity Temperature Coefficient
Noise
Current Consumption
Output Data Rate (ODR)
Filter -3dB Cutoff
Internal Oscillator Tolerance
Cross-Axis Sensitivity
Integral Non-Linearity
Transition Time
Data Ready Delay

For each parameter, the following information is provided:

Any aliases or other names for the parameter
A definition
Conditions under which the parameter is specified (typically more than one)
Distribution (e.g., minimum/typical/maximum)

Various timing diagrams and other graphs are used to illustrate the parameters.

And that’s pretty much all there is to it. A modest 60 pages (with lots of whitespace, easy to read). As promised, no more, no less.

You can find more on the announcement in their release; the document is available for download on the MIG website (you’ll need to provide your info).