I would like further clarification on nRF52840 Errata 179: RTC: COMPARE event is generated twice from a single RTC compare match.
I am creating a sensor system that needs to take samples at precise times so that readings from multiple sensors can be evaluated as a group.
I operate LFCLK from a very precise TXCO and use RTC0 as the system clock to schedule activities. I use several different RTC_COMPARE registers. All of the compare match events generate interrupts which cause a short task to execute, then modify the RTC_COMPARE register to schedule the next event time. One of the RTC_COMPARE events is connected to the SAADC TASKS_SAMPLE through the PPI. The compare event causes the TASKS_SAMPLE, then the RTC_COMPARE register is written with a new value for the next sample time.
Does this errata suggest that if I write to the RTC_COMPARE register that is connected to the SAADC through the PPI that this may cause a spurious compare match that (in my case) generate an extra TASKS_SAMPLE?
Does this errata suggest that if I write to a different RTC_COMPARE register than the one used to generate the SAADC TASKS_SAMPLE that this may also cause a second compare match?
Is it possible that even a read of an RTC_COMPARE register may cause the second compare match event?
Can you suggest any work around specific to the usage described above that allows this operation to function properly?