Re: [Paparazzi-devel] Auto Zero wiht IDG500

[Prof. Dr.-Ing. Heinrich Warmers]

Tanks for the answer Christophe,
i had just a look to CopterControl of Openpilot. In this circuit they use a 100nF C
connected from the AZ pin to ground.
We use this chip for our new version of the HB_mini autopilot.
But there is also a place for the IDG6000  or IDG6050 ;
we  will use this chips in future and can save money.

Heinrich


Christophe De Wagter schrieb:

We contacted invensense some years ago about the following:

We have several idg500 and isz500 gyro's in our products for a while but we suddenly ran into trouble when we started using the 4.5x amp together with the normal 1x output. Input currents into the 4.5x amplifier are measured to be 0.1 milliamp @ 100deg/sec. When the proposed external RC (750R/100nF) is used before the amp as in the datasheet, this significantly influences the measurement. Is it possible to get more information on the 4.5x amplifier and how to use it correctly? 

The solution was to connect the AZ pin to ground and not let it floating and it would be added to an update . In any case :http://paparazzi.enac.fr/wiki/IMU#YAI_v1.0 uses the fix. (http://svn.savannah.nongnu.org/viewvc/*checkout*/paparazzi-hardware/trunk/sensors/yai/imu.PDF?root=paparazzi)

So: never let AZ free.

-Christophe 

On Fri, Aug 3, 2012 at 9:33 AM, Prof. Dr.-Ing. Heinrich Warmers <address@hidden> wrote:

Hi,
knows  someone   what is to do with the auto zero  input  of the IDG500 rate sensor.
Let it free?  Set it to 3.V level? Connect it to an output to the micro controller to generate a pulse?
We saw yesterday that the measures turn left was 220 grd/s    to right  170 grd/s and the true value  was 198 grd/s as we fixed the pin to zero.
The gain was  in a wrong range.
After let the input disconnected we notice a other gain the the values were 196 grd/s  and 206 grd/s.
What is the benefits of using the the auto zero feature?

Heinrich



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