RE: RTC(s) interrupts and events

ovrebekk — Wed, 27 Nov 2019 14:21:17 GMT

Hi Bar

The nRF52840 has 3 separate RTC modules (RTC0, RTC1 and RTC2), and each of these has one PRESCALER register and 4 CC registers (CC[0], CC[1], CC[2] and CC[3]).

1. As mentioned above the 3 RTC's have independent PRESCALER registers.

2. Yes, 3 separate RTC counters with 4 CC registers each.

3. There is 1 TICK event and 4 COMPARE events for each of the 3 RTC modules.

4. Most peripherals in the nRF52 series only have the INTEN register, but since the RTC is optimized for ultra low power consumption they also added the EVTEN register which allows you to disable or enable events completely.

If you only need to pass an event over the PPI peripheral to a task in some other peripheral then you only need to enable the event in EVTEN. If you also want the event to generate an interrupt you need to enable it in INTEN also.

Events that you don't use for anything should be disabled in both INTEN and EVTEN to reduce the current consumption in sleep.

Best regards
Torbjørn