Increasing CPU clock frequency for BL653

[Ubaid_M]

Hi,

I am using nCS on nrf52833 based BL653dvk, I am based on default 32kHz CPU frequency.
I need to go higher up to 40MHz, kindly suggest what configuration options I can use to increase my CPU clock frequency up to 40MHz.

Thanks,

Ubaid 

[Jørgen Holmefjord]

Hi,

The CPU clock speed of nRF52833 is fixed at 64 MHz, this is not configurable to higher of lower frequencies.

Best regards,
Jørgen

[Jørgen Holmefjord]

Ubaid_M said:

So I am to understand that CPU frequency cannot be changed for nRF52833..?

Yes, the CPU frequency is fixed and cannot be changed.

Ubaid_M said:

So what is achieved by changing:

CONFIG_SYS_CLOCK_HW_CYCLES_PER_SEC=32768

&

CONFIG_SYS_CLOCK_TICKS_PER_SEC=32768

..?

This will change the system clock of the Zephyr RTOS, which is used by the Kernel Timing services and Timers. This system clock is by default running off the 32.768 kHz LFCLK and an RTC instance. This is not related to the frequency of the CPU, and how fast the CPU can execute tasks.

[Ubaid_M]

Jørgen Holmefjord said:

This will change the system clock of the Zephyr RTOS

So this means increasing this will also increase timing for kernel services calculation, like threads, msgQ etc,.

How much maximum can i increase this for nrf52833..?

Thanks

[Jørgen Holmefjord]

You can only change it to match the available clock sources.

The configs in this post should work on nRF52840, and thus likely also on nRF52833. Note that this is not low power and will keep the high-frequency clock running at all times.