I've noted an odd bug in the SAADC specifically with the Low Power Mode enabled. I used the SAADC to either gather data via Timer+PPI during a data collection mode, OR polling with triggering an SAADC Sample with nrfx_saadc_sample(). I've noticed that if I power cycle and program the board, if I manually trigger a measurement the callback is never triggered. If I restart the firmware this doesn't occur, only seen after a Power On Reset. This doesn't occur if I disable the Low Power Mode. I noted that there are some odd stipulations in the SAADC driver regarding manually triggering measurements, but this seems to be an odd bug. Is this expected behaviour? I use SDK15.2
What exactly do you mean by "manually trigger a measurement"? The Low Power Mode does not trigger the START task before the sample is triggered. If by manual you mean that you trigger the SAMPLE task by writing directly to the register, it would be expected that the callback never triggers. If you mean calling the function nrfx_saadc_sample() manually, this should handle this situation by triggering START task instead of SAMPLE task, and the SAMPLE task is triggered in IRQHandler when STARTED event is received.