Question about LIS3DH FIFO

[avieira]

Posted on February 12, 2014 at 17:44

Hello

I am trying to use the LIS3DH in FIFO Mode with Filter enabled.

In this mode, the X-Axis, and Y-Axis values get some normal values (they oscillate between -10 and +10) but the Z-Axis value seems to have a bypass to the filter mode, the Z-Axis gives for example -616 witch is not the value for Z-Axis if i disable FIFO and Filter.

Is this some kind of limitation of LIS3DH? or am i making something wrong at initialization.

In my initialization code the registers are initialized with the following values:

CTRL_REG1 = 0x17

CTRL_REG2 = 0x88

CTRL_REG3 = 0x00

CTRL_REG4 = 0x40

CTRL_REG5 = 0x40

CTRL_REG6 = 0x00

FIFO_CTRL_REG = 0x40

Thank You

Artur Vieira

[bw]

Posted on February 19, 2014 at 10:31

Hi,

There seem to bee a limitation in LIS3DH regarding using FIFO, HP-FILTER and the Z-axis

even though

it is not documented (yet?). The reply I got from the support team was that if this functionality was require the they suggested using the LIS2DH.

[avieira]

Posted on February 19, 2014 at 18:28

Hello

thanks for the feedback.

There i go redesign the PCB, since the footprint is not the same between LIS2D and LIS3D.

thanks

[bw]

Posted on February 20, 2014 at 09:55

Please notice that I have not yet worked with the LIS2DH, and can there for not confirm that the HP+FIFO configuration actual works on the Z-axis, and can't find and other source of confirmation on this.

[avieira]

Posted on February 20, 2014 at 12:21

Hi

I have asked to my local ST distributor if the LIS2DH has any problem for this kind of application.

I am waiting for his confirmation.

Thanks 

[avieira]

Posted on February 21, 2014 at 10:27

Hi

Just to update.

I get the confirmation from ST that there is a problem with LIS3DH when using FIFO + HP-Filter and Z-Axis.

Also get the confirmation, that LIS2 does not suffer from this problem.