NRF5340 system - I see glitches on sensitive analog every 30msec - seem correlated with Bluetooth. Does anything happen regularly?

[Kstern]

Working on a wearable health sensor using NRF5340.  Hard to be certain of correlation, but glitches of varying  magnitudes appear on my sensitive analog signals (as captured by my ADC) only on exact multiples of 30ms - larger glitches are mostly on multiples of 90ms.  Wearable is connected to Android phone.

If you can describe anything that happens as part of the various BLE protocols, that occurs every 30ms, that could give me a strong clue to help track root cause.

[Mariano Goluboff]

The BLE connection interval is 7.5ms to 4 seconds, with increments of 1.25ms. It is possible that 30ms is the connection interval for the connection to the phone. You can learn more about the connection interval in Lesson 3 of the Bluetooth Low Energy Fundamentals DevAcademy course.

Exercise 2 in that lesson has an example of how to print out the connection parameters for the connection, so that might help track what the interval really is.