The datasheet says:
18.104.22.168 "System clock (CLK_PER) is required to be at least four times faster than RTC clock (CLK_RTC) for reading counter
value, and this is regardless of the RTC_PRESC setting."
Does anyone know if this applies only to the actual RTC counter (RTC_CNT) or if it means any of the RTC 16-bit or 8-bit registers? And does it apply only to reading, or also to writing? I don't need to read the RTC_CNT. I could just write once to RTC_PER and then poll the overflow interrupt flag to keep track of time.
Also, the block diagram in the ATtiny416 clock section (10.2.1) clearly shows a 32.768 kHz external signal going to both CLK_PER and CLK_RTC. But the datasheet says:
23.8 "Both the RTC and the PIT are asynchronous, operating from a different clock source (CLK_RTC) independently of
the main clock (CLK_PER)."
If I want to run the entire chip at 32.768 kHz, do I need to use the internal 32 kHz oscillator for CLK_PER and the external 32 kHz crystal for the RTC?