Disable SoftDevice, disable HFCLK and use app timer driven by LFCLK

[keigo]

Device: nRF52811

Board: custom (EYSNSNZWW module is used)

SDK: 16.0.0

SoftDevice: S112(v7.0.1)

Sample Project: ble_app_uart 

I'd like to reduce current consumption while BLE communication is not used and the device is inactive.

So is it possible to disable SoftDevice, disable HFCLK and use app timer driven by LFCLK?

The reason app timer is used in the inactive state is that the device should be wake up at a certain interval.

Thanks.

[Jared]

Hi,

You can disable the Softdevice and HFCLK (if it hasn't been started explicit) by calling nrf_sdh_disable_request(). App timer will use the RTC which again will use the LFCLK. Not sure if you had any specific questions regarding this?

regards

Jared 

[keigo]

Thank you for your support.

I managed to disable SoftDevice, but I cannot disable HFCLK.

Could you tell me how to disable HFCLK?

Thanks.

[Jared]

Hi,

Disabling the Softdevice should disable the HFCLK unless you have turned it on explicitly before initializing the Softdevice. How do you verify the state of the HFCLK?

regards

Jared 

[keigo]

Thank you for your support.

Just let me confirm. Which is correct?

"Disabling HFCLK" means:

-HFXO is disabled but HFINT is enabled

-HFXO and HFINT are diabled

I"d like to disable both HFXO and HFINT, then enable LFCLK for RTC.

Thanks.

[Jared]

Hi,

It would mean disabling effectively stopping HFXO and HFINT. RTC will automatically use the LFCLK when it's enabled. How do you verify the state of HFCLK? Do you check the HFCLK stat register?

regards

Jared

[keigo]

Thank you for your support.

I have checked HFCLKSTAT and it indicated "HFCLK running".

By the way, is it no problem with using J-Link debugger for the device running only with LFCLK?

Thanks.

[Jared]

Yes, the debugger will activate it. On a second thought, disabling the HFCLK completely is very difficult as many of the peripherals is dependent on it. What current do you measure and what is your requirement? I think the most effective method would be to just disconnect and stop advertising and then go to IDLE sleep instead of trying to disable the HFCLK completely.

regards

Jared 

[keigo]

Thank you for your support.

You mean debugger will activate HFCLK even if HFCLK is disabled before connecting debugger, is it correct?

Thanks.

[Jared]

Hi,

Correct.

regards

Jared 

[keigo]

Thank you for your support.

I finally succeeded in disabling HFCLK. The current dropped dynamically so I concluded that the HFCLK stopped.

In my case, the SAADC remained enabled. It kept HFCLK enabled.

Thanks.