LSM6DSV80x SLFP game rotation vector, and timestamp to fifo

[jose365ww]

Hi there, 

I'm trying to program LSM6DSV80x to read sensor values in -500Hz for a certain period of time and send them for process (thus no realtime process, but need timestamps).  The sensor values include xl, hg_xl, gyro, and also Game rotation vector, gravity calculated by SFLP.  According to the use case, all values will be read through FIFO.  Mostly works well but I've come up with two questions.  

- What timestamp means? Is it time of the latest FIFO entry,  or of the next FIFO entry, or irrelevant with other entries?

- for game rotation vector, I got two consequtive entries having TAG=19 in FIFO everytime,  at the same timing.  Those two entries have completely different values. With the application note and the post in this forum, I understand the FIFO  entry for game rotation vector hold only x, y, z elements and w needs to be calculated at the host side.  For example (the order is, w - which I calculate, x, y, z):

LSM6DSV80X_SFLP_GAME_ROTATION_VECTOR_TAG game_rotation_mg: 0.81 0.00 -0.09 -0.32
LSM6DSV80X_SFLP_GAME_ROTATION_VECTOR_TAG game_rotation_mg: 0.24 0.00 0.31 0.89

How can I interpret these values?

Any comments are appreciated!

[casadeib]

Hi @jose365ww

 

-As for the Timestamp doubt, it represents the timestamp of the right after FIFO DATA.

-As for the game rotation vector, please refer to the AN6281 paragraph 8.6.3, in order to better understand the content of each FIFO register for both the TAG_SENSOR = 0x13. The first represents the first word in Table 90, and the second TAG 0x13 represents the secondo word in Table 91

 

 

[jose365ww]

Thanks for your help, @casadeib !

I thought I read through AN6281 but missed this description.

 

[carterhenry56]

If the game rotation vector isn’t aligned with FIFO timestamps, motion updates get choppy. I checked this while experimenting with different builds, including the super bear adventure mod apk God Mod, and the responsiveness was clearly better when the sensor timing was accurate. So yeah, FIFO timing plays a huge role in overall gameplay fluidity.