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Helmut Tschemernjak
Associate II
July 30, 2016
Question

LSM303AGR, accelerometer noice problem (more than 100mg)

  • July 30, 2016
  • 3 replies
  • 769 views
Posted on July 30, 2016 at 18:46

I have a problem with the accelerometer noice, I feel that 100mg noise for the mode 2G, 10 Hz-Normal, BDU, HR (12bits) is way too much. In my setup I use your STEVAL board on an idle table without any vibration doing measurements for about 10 seconds.

Here are my results.

00:05:04.309034 XYZ: X(-0.9682) Y(-0.0167) Z(-0.2519)

00:05:04.410438 XYZ: X(-0.9702) Y(-0.0147) Z(-0.2440)

00:05:05.511833 XYZ: X(-0.9722) Y(-0.0157) Z(-0.2528)

00:05:05.613250 XYZ: X(-0.9722) Y(-0.0127) Z(-0.2528)

00:05:05.714657 XYZ: X(-0.9702) Y(-0.0137) Z(-0.2499)

00:05:05.816065 XYZ: X(-0.9702) Y(-0.0098) Z(-0.2568)

00:05:05.917417 XYZ: X(-0.9702) Y(-0.0137) Z(-0.2519)

00:05:05.188270 XYZ: X(-0.9673) Y(-0.0167) Z(-0.2509)

00:05:05.120178 XYZ: X(-0.9722) Y(-0.0118) Z(-0.2489)

00:05:05.221579 XYZ: X(-0.9692) Y(-0.0069) Z(-0.2509)

00:05:05.322933 XYZ: X(-0.9673) Y(-0.0108) Z(-0.2499)

00:05:05.424334 XYZ: X(-0.9702) Y(-0.0118) Z(-0.2548)

00:05:06.525737 XYZ: X(-0.9712) Y(-0.0137) Z(-0.2548)

00:05:06.627142 XYZ: X(-0.9682) Y(-0.0127) Z(-0.2499)

00:05:06.728551 XYZ: X(-0.9624) Y(-0.0137) Z(-0.2470)

00:05:06.829954 XYZ: X(-0.9702) Y(-0.0176) Z(-0.2460)

00:05:06.931355 XYZ: X(-0.9663) Y(-0.0186) Z(-0.2499)

00:05:06.327590 XYZ: X(-0.9722) Y(-0.0157) Z(-0.2470)

00:05:06.134111 XYZ: X(-0.9692) Y(-0.0206) Z(-0.2489)

00:05:06.235508 XYZ: X(-0.9712) Y(-0.0167) Z(-0.2489)

00:05:06.336912 XYZ: X(-0.9682) Y(-0.0157) Z(-0.2548)

00:05:06.438313 XYZ: X(-0.9692) Y(-0.0157) Z(-0.2528)

00:05:07.539719 XYZ: X(-0.9702) Y(-0.0186) Z(-0.2519)

00:05:07.641124 XYZ: X(-0.9741) Y(-0.0196) Z(-0.2470)

00:05:07.742525 XYZ: X(-0.9731) Y(-0.0167) Z(-0.2479)

00:05:07.843927 XYZ: X(-0.9673) Y(-0.0127) Z(-0.2479)

00:05:07.945328 XYZ: X(-0.9663) Y(-0.0157) Z(-0.2470)

00:05:07.467340 XYZ: X(-0.9673) Y(-0.0157) Z(-0.2509)

00:05:07.148087 XYZ: X(-0.9682) Y(-0.0147) Z(-0.2519)

00:05:07.249485 XYZ: X(-0.9663) Y(-0.0157) Z(-0.2489)

00:05:07.350888 XYZ: X(-0.9673) Y(-0.0167) Z(-0.2509)

00:05:07.452288 XYZ: X(-0.9663) Y(-0.0147) Z(-0.2528)

00:05:08.553688 XYZ: X(-0.9682) Y(-0.0196) Z(-0.2548)

00:05:08.655089 XYZ: X(-0.9643) Y(-0.0167) Z(-0.2528)

00:05:08.756492 XYZ: X(-0.9673) Y(-0.0167) Z(-0.2509)

00:05:08.857897 XYZ: X(-0.9682) Y(-0.0137) Z(-0.2528)

00:05:08.959300 XYZ: X(-0.9702) Y(-0.0127) Z(-0.2499)

00:05:08.607110 XYZ: X(-0.9722) Y(-0.0127) Z(-0.2499)

00:05:08.162064 XYZ: X(-0.9741) Y(-0.0137) Z(-0.2568)

00:05:08.363515 XYZ: X(-0.9702) Y(-0.0157) Z(-0.2509)

00:05:08.464924 XYZ: X(-0.9673) Y(-0.0186) Z(-0.2499)

00:05:09.566323 XYZ: X(-0.9682) Y(-0.0157) Z(-0.2489)

00:05:09.667726 XYZ: X(-0.9682) Y(-0.0157) Z(-0.2450)

00:05:09.769120 XYZ: X(-0.9692) Y(-0.0167) Z(-0.2440)

00:05:09.870518 XYZ: X(-0.9702) Y(-0.0176) Z(-0.2509)

00:05:09.971921 XYZ: X(-0.9673) Y(-0.0137) Z(-0.2489)

00:05:09.73329  XYZ: X(-0.9692) Y(-0.0167) Z(-0.2479)

00:05:09.174682 XYZ: X(-0.9702) Y(-0.0118) Z(-0.2470)

00:05:09.276082 XYZ: X(-0.9673) Y(-0.0127) Z(-0.2479)

00:05:09.377483 XYZ: X(-0.9653) Y(-0.0147) Z(-0.2499)

00:05:10.478889 XYZ: X(-0.9663) Y(-0.0137) Z(-0.2470)

00:05:10.580295 XYZ: X(-0.9633) Y(-0.0137) Z(-0.2479)

00:05:10.681700 XYZ: X(-0.9633) Y(-0.0098) Z(-0.2499)

00:05:10.783050 XYZ: X(-0.9663) Y(-0.0137) Z(-0.2411)

00:05:10.884457 XYZ: X(-0.9702) Y(-0.0147) Z(-0.2450)

00:05:10.985864 XYZ: X(-0.9682) Y(-0.0147) Z(-0.2460)

00:05:10.87265  XYZ: X(-0.9682) Y(-0.0137) Z(-0.2470)

00:05:10.188616 XYZ: X(-0.9673) Y(-0.0127) Z(-0.2470)

00:05:10.290018 XYZ: X(-0.9653) Y(-0.0118) Z(-0.2499)

00:05:10.391419 XYZ: X(-0.9663) Y(-0.0157) Z(-0.2470)

00:05:11.492825 XYZ: X(-0.9673) Y(-0.0137) Z(-0.2519)

00:05:11.594224 XYZ: X(-0.9673) Y(-0.0127) Z(-0.2538)

00:05:11.695630 XYZ: X(-0.9780) Y(-0.0078) Z(-0.2568)

00:05:11.796989 XYZ: X(-0.9692) Y(-0.0127) Z(-0.2558)

00:05:11.898398 XYZ: X(-0.9682) Y(-0.0098) Z(-0.2548)

00:05:11.999756 XYZ: X(-0.9722) Y(-0.0157) Z(-0.2489)

00:05:11.101165 XYZ: X(-0.9712) Y(-0.0137) Z(-0.2548)

00:05:11.202570 XYZ: X(-0.9653) Y(-0.0167) Z(-0.2509)

00:05:11.303969 XYZ: X(-0.9624) Y(-0.0157) Z(-0.2509)

00:05:11.405378 XYZ: X(-0.9614) Y(-0.0176) Z(-0.2489)

00:05:12.506779 XYZ: X(-0.9633) Y(-0.0157) Z(-0.2519)

00:05:12.608190 XYZ: X(-0.9682) Y(-0.0137) Z(-0.2489)

00:05:12.709594 XYZ: X(-0.9663) Y(-0.0147) Z(-0.2499)

00:05:12.811001 XYZ: X(-0.9663) Y(-0.0137) Z(-0.2489)

00:05:12.912404 XYZ: X(-0.9643) Y(-0.0176) Z(-0.2489)

00:05:12.138020 XYZ: X(-0.9633) Y(-0.0176) Z(-0.2509)

00:05:12.115151 XYZ: X(-0.9653) Y(-0.0157) Z(-0.2479)

00:05:12.216557 XYZ: X(-0.9702) Y(-0.0078) Z(-0.2411)

00:05:12.317912 XYZ: X(-0.9682) Y(-0.0118) Z(-0.2460)

00:05:12.419319 XYZ: X(-0.9692) Y(-0.0147) Z(-0.2421)

00:05:13.520719 XYZ: X(-0.9682) Y(-0.0137) Z(-0.2587)

00:05:13.622118 XYZ: X(-0.9653) Y(-0.0137) Z(-0.2548)

00:05:13.723525 XYZ: X(-0.9673) Y(-0.0098) Z(-0.2548)

00:05:13.824881 XYZ: X(-0.9682) Y(-0.0098) Z(-0.2509)

00:05:13.926232 XYZ: X(-0.9663) Y(-0.0137) Z(-0.2489)

00:05:13.27639  XYZ: X(-0.9663) Y(-0.0127) Z(-0.2470)

00:05:13.128989 XYZ: X(-0.9682) Y(-0.0176) Z(-0.2489)

00:05:13.230382 XYZ: X(-0.9682) Y(-0.0167) Z(-0.2460)

00:05:13.331784 XYZ: X(-0.9663) Y(-0.0176) Z(-0.2450)

00:05:13.433184 XYZ: X(-0.9663) Y(-0.0137) Z(-0.2489)

00:05:14.534584 XYZ: X(-0.9653) Y(-0.0176) Z(-0.2499)

00:05:14.635982 XYZ: X(-0.9653) Y(-0.0157) Z(-0.2499)

00:05:14.737389 XYZ: X(-0.9682) Y(-0.0137) Z(-0.2509)

00:05:14.838790 XYZ: X(-0.9702) Y(-0.0147) Z(-0.2528)

00:05:14.940194 XYZ: X(-0.9731) Y(-0.0127) Z(-0.2499)

00:05:14.41602  XYZ: X(-0.9663) Y(-0.0118) Z(-0.2528)

00:05:14.142948 XYZ: X(-0.9673) Y(-0.0176) Z(-0.2470)

00:05:14.244351 XYZ: X(-0.9673) Y(-0.0206) Z(-0.2509)

This means:

X Y Z

Min -0.9741 -0.0206 -0.2568

Max -0.9624 -0.0069 -0.2440

Average -0.9689 -0.0150 -0.2506

Is this normal? I used a Bosch BMC150 in the past and had different results.

When I use the AGR threshold high-pass filter using a 40mg 

threshold I get no noice, unless I move the device. It looks like to 

threshold is doing an averaging of three samples.

Any ideas?

Thank you for your help.
This topic has been closed for replies.

3 replies

ST Employee
August 2, 2016
Posted on August 02, 2016 at 15:32

I analyzed your data. Below are the results.

In concussion the peak-peak value of the signal noise is 17, 14, 18 mg [X,Y,Z axis] and standard deviation which is equal to RMS noise is 3 mg. It is in line with specification. I don’t see any problem with the noise in your data as you have reported.

X

Y

Z

Min

-0.978

-0.021

-0.259

Max

-0.961

-0.007

-0.241

Avg

-0.968

-0.015

-0.250

Stdev

0.003

0.003

0.003

Delta (Max-Min)

0.017

0.014

0.018

Best regards

Miroslav

Helmut Tschemernjak
Associate II
August 3, 2016
Posted on August 03, 2016 at 16:31

Dear Miroslav,

thank you for taking the time and explaining to me that this is 

normal behaviour.

Regards Helmut

Helmut Tschemernjak
Associate II
August 4, 2016
Posted on August 04, 2016 at 09:31

Dear Miroslav,

I have to apologise, I figured out today that my table is

http://www.dict.cc/englisch-deutsch/wobble.html

ing a little bit, as well the floor finish. Puting the device into another localtion gives me much better and more stable result. I had truly100mg changes on my table, how it is down to 10mg.

Thank you, Helmut