ST LSM6DS3TR-C Gyro LP Filter

Jonathan Beard · ‎2023-09-01

The LSM6DS3TR-C datasheet "Gyroscope LPF1 bandwidth selection" table mentions BWs for 800Hz, 1.6kHz, 3.3kHz and 6.6kHz ODRs. In the same datasheet, the "Gyroscope ODR configuration setting" table lists ODRs of 12.5Hz, 26Hz, 52Hz, 104Hz, 208Hz, 416Hz, 833Hz, 1.66Hz, 3.33Hz, 6.66Hz.

Question: Why don't the ODRs mentioned in these two tables have the same values? Am I supposed to assume 800Hz in one table is the same as 833Hz in the other table?

Question: I'd like to set my gyro ODR to ~200Hz with a ~100Hz BW acting as an anti-aliasing filter. Is that possible? I can achieve this with the accel. Why is it not mentioned in the "Gyroscope LPF1 bandwidth selection" table? If this is not possible, what is the reasoning to provide such an ODR-BW combination for the accel, but not the gyro?

Federica Bossi · ‎2023-09-05

Hi @Jonathan Beard ,

Welcome to ST Community!

Yes, 800Hz is an approximation of 833Hz.

For your second question, please refer to Table 11 in the AN5130 where you find the gyroscope overall bandwidth selection.

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Jonathan Beard · ‎2023-09-11

Datasheet AN5130 Table 11 includes columns for ODR and cutoff, but all the cutoff frequencies for an ODR of 208Hz are the same (67Hz). I was hoping to see a row for a 200Hz ODR and a 100Hz cutoff/bandwidth. I can't tell if 67Hz is closer to a ODR/2, ODR/3, or ODR/4 range. Generally I look for an anti-aliasing filter with an ODR/2 range. I see that the cutoff frequencies for a 200Hz ODR are {<empty>, 40°, 42°, 45°, 39°}. These are all pretty much the same. What is the difference between them? How should I convert these to delays in seconds? I'm assuming 40° / 360° / 200Hz = 0.55e-3s. What does an empty cutoff frequency imply?

Roger SHIVELY · ‎2023-09-13

Hello @Jonathan Beard ,

There has been a case created to resolve this question and we will be reaching out to you directly.

Regards,
Roger