RE: Clock frequency, HW clock & RTOS tick time

Einar Thorsrud — Mon, 21 Nov 2022 13:16:19 GMT

Hi Hitesh,

I think there may be some misunderstandings here.

First of all, the CPU clock on the nRF52833 is always 64 MHz (using a 32 MHz reference). There are no configuration change you can do to influence this.

When it comes to the RTOS / Zephyr clock source, this is based on the RTC. The RTC runs of the 37.768 kHz oscillator , so the highest possible frequency you can use is 32768 Hz, which is what is used in the nRF Connect SDK. Setting CONFIG_SYS_CLOCK_HW_CYCLES_PER_SEC=100000 would simply not work. Also, using a lower value serves no practical purpose (you could use the RTC prescaler to et a lower frequency and adjust the configuration for that, but you would not gain anything by doing so).