ESP32 Forum

Hi all.
So, a pet peeve of mine is technical documentation that uses abbreviations and acronyms without first defining them. IMO, the Espressif documents are replete with this issue. Several references that I keep coming across are “RTC”, “RTC Slow Memory”, “RTC Fast Memory”.

In typical technical usage, “RTC” refers to, of course, a “Real Time Clock”. But this does not seem to be the case in the ESP32 documents. There are many pages written about the RTC and its features, but never once is it mentioned what “RTC” stand for. So, first question … what does “RTC” stand for and what is it?

Next are the “RTC Memories”. These memories hold data for what purpose related to whatever the RTC is? Why is one “Fast” and one “Slow”. And, “Fast” and “Slow” relative to what? The documents (at least the ones that I’ve found) never address those basic topics.

So, thanks in advance to anyone who can shed some light on these basic ideas.

The TRM does include a Glossary that defines RTC:

Real Time Controller. A group of circuits in SoC that keeps working in any chip mode and at any time.

And clarifies how RTC Slow and Fast memory got their names in 1.3.5.3:

The ROM as well as the SRAM are both clocked from CPU_CLK and can be accessed by the CPU in a single cycle.
The RTC FAST memory is clocked from the APB_CLOCK and the RTC SLOW memory from the FAST_CLOCK, so access to these memories may be slower.