Analysis of Clock source

RE: Analysis of Clock source

Håkon Alseth — Tue, 21 Apr 2020 11:03:41 GMT

[quote user="shruti mishra"]1. According to initial values in LFCLKSTAT register which is [1:0] ,Board is using 32kHZ clock source initially. means 1 refers to the LFRC and 0 refers to the requested LFCLK source has not been started. [/quote]

The clock source is set by the kernel, with this symbol:

https://github.com/NordicPlayground/fw-nrfconnect-zephyr/blob/v2.1.99-ncs1/drivers/clock_control/Kconfig.nrf#L27

It is not started until the kernel has started the LFCLK.

[quote user="shruti mishra"]But why the status is not running . To show the status as running we need to trigger the NRF_CLOCK->TASKS_LFCLKSTART = 1; then what will be the difference . means both the cases using the same clock of 32kHz.[/quote]

I think you're breaking before main, at which point the kernel hasn't booted up properly yet. Can you try breaking in main and see if the clocks are set properly?

Kind regards,

Håkon

RE: Analysis of Clock source

shruti mishra — Tue, 21 Apr 2020 10:38:43 GMT

Hi Hakon

Could you please verify these points also-

1. According to initial values in LFCLKSTAT register which is [1:0] ,Board is using 32kHZ clock source initially. means 1 refers to the LFRC and 0 refers to the requested LFCLK source has not been started.

But why the status is not running . To show the status as running we need to trigger the NRF_CLOCK->TASKS_LFCLKSTART = 1; then what will be the difference . means both the cases using the same clock of 32kHz.

RE: Analysis of Clock source

Håkon Alseth — Tue, 21 Apr 2020 07:31:16 GMT

Hi,

There's two clock sources:

* HFCLK

* LFCLK (automatically started by the zephyr kernel)

You are changing the LFCLK (32.768 kHz) and inspecting the HFCLK registers. Try triggering

NRF_CLOCK->TASKS_HFCLKSTART = 1;

while (NRF_CLOCK->EVENTS_HFCLKSTARTED == 0);

Then checking HFCLKSTAT register.

Kind regards,

Håkon