on my imx6 board BMI270 accel and gyro ODR is set to 100 Hz. In this case period is 1/100 = 10000 uS. With every received sample from accel I'm adding 10000 uS to our BMI270 timer. After some time there is a drift between system timer and BMI270 timer. This drift is increasing - timer on BMI270 is running slower.
Is my calculation correct ? Do I need to add some data transfer time ?
Since BMI don't have external crystal oscillator - can you tell me how accurate this time is ?
If you enable accel and gyro sensors for BMI270, you can achieve 1% accuracy.
Of course, it might be some error due to temperature, but less impact than ODR accuracy.
I don't think there is some drift, but for sure there is some deviation.
Therefore, my suggestion is to use sensor time from MCU side for output value on BMI270 since BMI270 has 1% deviation.
Please let me know if you have any quesitons.