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LIS3DSH: incorrect update frequency

kazu hara
Associate II
Posted on November 27, 2017 at 09:10

Hello All,

I configured ODR to 1600Hz at CTRL4 register on LIS3DSH.

It works perfectly except for update frequency.

INT1 pulse outputs with 600us interval! I attached Oscilloscpe at INT1 pin.

It should be 625us(1s/1600 = 625us).

Could anyone kindly help me what is wrong with my setting, hardware...?

0690X00000608qAQAQ.png
1 ACCEPTED SOLUTION

Accepted Solutions
Miroslav BATEK
ST Employee
Posted on November 27, 2017 at 14:19

I don't think it is an issue. The ODR value in datasheet is typical value and can be slightly different in each sensor.

View solution in original post

7 REPLIES 7
Miroslav BATEK
ST Employee
Posted on November 27, 2017 at 14:19

I don't think it is an issue. The ODR value in datasheet is typical value and can be slightly different in each sensor.

kazu hara
Associate II
Posted on November 27, 2017 at 15:12

Ok, I understand it is spec.

So if I want to get INT1 interrupt with exactly 625us interval, what should I do?

Posted on November 27, 2017 at 17:51

Unfortunately it is not possible to fine tune or adjust the ODR, so it won't be possible to achieve exactly 625us.

kazu hara
Associate II
Posted on November 28, 2017 at 04:05

Thank you very much for useful information, Miroslav.

I will use something like interpolation in order to get fine value.

kazu hara
Associate II
Posted on November 28, 2017 at 06:03

I have one more question.

How much % is frequecy error of INT1 interval in worst case at LIS3DSH product?

For example, 1600Hz+-10% or something.

It is necessary for calculating buffer size for interpolation.

Posted on November 28, 2017 at 14:27

Unfortunately the ODR tolerance is not specified for consumer MEMS sensors.

I think +/- 10% should be enough, but ST doesn't guarantee it.
kazu hara
Associate II
Posted on November 29, 2017 at 08:18

Thank you for useful practical information, Miroslav.

This is very good experience for me that I wll be cafeful for using consumer MEMS.