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I have the factory firmware logging Accel, Gyro and Magnetometer data at 100 Hz, and in the files I get about 12 readings in a row separated by 9 - 11 milliseconds, as expected, but then the 13th would be logged with a long lag - usually 70-90 milliseconds, or sometimes ~140 milliseconds, and on some rare occasions 3 - 4 seconds.

The readings during active movement seem mostly normal on these lag events, but when the device is not moving, there are some spurious high G / high gyro readings and they seem to only occur during those lag events. So to be safe, during movement experiments, I need to laboriously strip out those readings associated with the lag events in order to make sure the data quality is ok. That means that only 50-70% (roughly) of the possible data recordings (if it really logged at the full 100 Hz) are available, due to the dead-time lags.

I assume this has to do with the interrupts that others have mentioned. If there is a simple tweak to clear the problem I'd love to know how to fix it. Or could it be a problem specific to the board or memory card (I have a 32 Gb Samsung EVO card)?
Last edited by brydenrh on Mon May 27, 2019 1:50 pm, edited 1 time in total.
Here is a plot of the lag between readings over the course of 100 seconds. Obviously there is a pattern to the excessive lags.
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