RTC

[Mair]

Originally posted by Werner

In the context of ULP I always read the term RTC subsystem or RTC domain. I only know this abbreviation as Real Time Clock, but that doesn´t seem to fit here. I have searched all the documentation and there are hundreds of hits, but nowhere is the term explained. Could you help me out in this question?

[Mair]

Hi Werner,

It is a bit confusing.
RTC also stands for Real Time Clock but not only in the sense of only keeping time (as it usually is) but more in the sense of that section of the chip responsible for keeping time and timers which function from an internal RC oscillation or an external Chrystal.
It’s a foundation piece of the architecture.
The RTC consist of the ULP, some RAM (which can store memory between deep sleeps and resets) and the PMU (Phasor Measurement Unit) which is responsible for synchronising time from the clock signals.

From my understanding
• the RTC controlled by the ULP has access to some peripherals including GPIO which is how we can use a GPIO to wake the chip up from sleep
• RTC memory can persist time through deep sleeps and resets like in the traditional sense but, we can also set RTC memory and persist other data as well.
• RTC timers are used to maintain time of day during deep sleep and resets but, we can also use the RTC timers for other timing functions as well

hope this helps,

Mair