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JMatt
Associate
March 11, 2021
Solved

I'm using the LIS3DH. Do I need to provide a 90 mS delay between configuration of CTRL_REG1 and reading the OUT registers or the FIFO to insure stable output ?

  • March 11, 2021
  • 2 replies
  • 861 views

I'm using the LIS3DH. The Application Note AN3308 specifies a 90 mS delay time between configuration and reading data in the suggested procedure for performing a self test, (p57 of DocID18198 Rev 3). The delay is, "... for stable output".  Once ODR is set or FIFO enabled, is a delay required to insure stable data? If so, how long of a delay is adequate? 90 mS eats up a lot of power while the LIS3DH is just sitting there. Would 5 mS or 0 mS be OK?

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Best answer by Eleon BORLINI

Hi @JMatt​ ,

This 90ms delay refer to the Self Test condition only, which is sensible to small variation since the actuation force applied to the sensor (simulating a definite input acceleration) is huge. 

It is not necessary to wait such delay for a standard acquisition (continuous or FIFO mode).

Of course, you'll need 1/ODR to get a valid data after internal digital conversion. Moreover, it is a general recommendation to discard the first sample coming just after the register configuration.

For a general overview on the power-on timings, I suggest you to check the datasheet p.16 and 17 (following tables):

0693W000008wbqgQAA.pngIf my reply answered your question, please click on Select as Best at the bottom of this post. This will help other users with the same issue to find the answer faster. 

-Eleon

2 replies

Eleon BORLINI
Eleon BORLINIBest answer
ST Employee
March 11, 2021

Hi @JMatt​ ,

This 90ms delay refer to the Self Test condition only, which is sensible to small variation since the actuation force applied to the sensor (simulating a definite input acceleration) is huge. 

It is not necessary to wait such delay for a standard acquisition (continuous or FIFO mode).

Of course, you'll need 1/ODR to get a valid data after internal digital conversion. Moreover, it is a general recommendation to discard the first sample coming just after the register configuration.

For a general overview on the power-on timings, I suggest you to check the datasheet p.16 and 17 (following tables):

0693W000008wbqgQAA.pngIf my reply answered your question, please click on Select as Best at the bottom of this post. This will help other users with the same issue to find the answer faster. 

-Eleon

JMatt
JMattAuthor
Associate
March 11, 2021

Thank you.