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Electronics => Projects => Topic started by: hamid9543 on November 08, 2013, 10:22:42 10:22



Title: l3g4200d
Post by: hamid9543 on November 08, 2013, 10:22:42 10:22
meaning of sensitivity and deg/s for l3g4200d?


Title: Re: l3g4200d
Post by: PaulC on November 08, 2013, 12:43:17 12:43
need just a little bit more info from you to give a little bit more info back..

Data Sheet says :

L3G4200D Mechanical and electrical characteristics
Doc ID 17116 Rev 3 15/42
2.6 Terminology
2.6.1 Sensitivity
An angular rate gyroscope is a device that produces a positive-going digital output for
counter clockwise rotation around the sensitive axis considered. Sensitivity describes the
gain of the sensor and can be determined by applying a defined angular velocity to it. This
value changes very little over temperature and time.

2.6.2 Zero-rate level
Zero-rate level describes the actual output signal if there is no angular rate present. The
zero-rate level of precise MEMS sensors is, to some extent, a result of stress to the sensor
and, therefore, the zero-rate level can slightly change after mounting the sensor onto a
printed circuit board or after exposing it to extensive mechanical stress. This value changes
very little over temperature and time.
2.6.3 Stability over temperature and time
Thanks to the unique single driving mass approach and optimized design, ST gyroscopes
are able to guarantee a perfect match of the MEMS mechanical mass and the ASIC
interface, and deliver unprecedented levels of stability over temperature and time.
With Zero rate level and sensitivity performances, up to ten times better than equivalent
products now available on the market, L3G4200D allows the user to avoid any further
compensation and calibration during production for faster time to market, easy application
implementation, higher performances and cost saving.

also

Sensitivity is described on page 10 of the datasheet. Output is generally digital counts relative to full scale. (signed 16-bit)
According to the data sheet, at 2000dps use a scale factor of 70x10-3 dps/digit which gives a range of +/-28572 , ie., a value of 285 is roughly 20dps.

The output values are scaled according to the sensitivity you select. At 250dps sensitivity, you must multiply by .00875 to get degrees per second.


Title: Re: l3g4200d
Post by: hamid9543 on November 08, 2013, 03:27:56 15:27
you copy and paste from datasheet!!!!
and i read datasheet several times.
my question:
 what characteristics of sensor is defined by sensitivity and deg/s?
please explains deg/s with an example.


Title: Re: l3g4200d
Post by: Xwing on November 08, 2013, 04:47:21 16:47
what characteristics of sensor is defined by sensitivity and deg/s?

It's the angular velocity


Title: Re: l3g4200d
Post by: PaulC on November 08, 2013, 04:59:57 16:59
ouch !

meaning of sensitivity and deg/s for l3g4200d?
2.6.1 Sensitivity
An angular rate gyroscope is a device that produces a positive-going digital output for
counter clockwise rotation around the sensitive axis considered. Sensitivity describes the
gain of the sensor and can be determined by applying a defined angular velocity to it. This
value changes very little over temperature and time.


Title: Re: l3g4200d
Post by: solutions on November 09, 2013, 07:51:14 07:51
Sensitivity means that if you build this (you do realize that part number is leetspeak, don't you?) into a missile, mothers will cry over the children it tore apart.

More seriously, it's a really good idea to put an end to you being an international man of mystery and to tell us what you are doing with this because you clearly have no clue (please do not take this as an insult or personal attack - it's mere observation)

Those parameters are bounded by the system requirements, not a datasheet.

More, or less, doesn't mean "better"

So, what's this for and how will it be used?