SOFTDEVICE DISABLE ISSUE WHILE WDT IS RUNNING

[Embel_Tech]

Hello,

I need to write to the UICR flash multiple times. Typically, this involves disabling the softdevice, writing to the UICR, and then re-enabling the softdevice. However, when the software WDT is enabled, this process becomes problematic. The enabled WDT prevents the low-frequency clock (lfclk) from stopping, thus preventing the softdevice from being disabled.

Is there a way to disable the WDT functionality temporarily and re-enable it after writing to the UICR?

[Sigurd]

Hi!

Is there a way to disable the WDT functionality temporarily and re-enable it after writing to the UICR?

No.

thus preventing the softdevice from being disabled.

How did you confirm this?

PS: There is a known issue with WDT + RTC + software reset in nRF5-SDK v17, file nrf_drv_clock.c , see this page:  RE: FreeRTOS+WDT+SDK17 problem 

[Embel_Tech]

      We are using SDK 15.0.0. WDT preventing the softdevice disabled, because while disabling softdevice there is internal function call for lfclk_stop(), but due to WDT enable, lfclk() forcefully started and hence softdevice is not disabling. so, we can't be able to write to UICR.
    How to disable the softdevice when WDT is enabled??? waiting for your reply.

[Sigurd]

Embel_Tech said:

because while disabling softdevice there is internal function call for lfclk_stop()

What function are you using to disable the softdevice, that is calling lfclk_stop() ?

[Embel_Tech]

I am using nrf_sdh_disable_request(); and then sd_softdevice_disable(); functions to disable the soft device, which calls nrf_drv_clock_lfclk_release(); in event: NRF_SDH_EVT_STATE_DISABLED of soft device enable/disable state handler. 

   By commenting nrf_drv_clock_lfclk_release(); in NRF_SDH_EVT_STATE_DISABLED event there was no issue while disabling the soft device. is it ok to comment nrf_drv_clock_lfclk_release(); for my application.

There will be any impact on other functionalities due to commenting nrf_drv_clock_lfclk_release();  ??????

[Embel_Tech]

What is purpose of calling nrf_drv_clock_lfclk_release(); in NRF_SDH_EVT_STATE_DISABLED event??

[Sigurd]

I think the best approach here is to save some config somewhere that you want to write to UICR on next reset. Reset the chip, write to UICR early in main before you enable the SoftDevice, reset the chip again(for the new UICR to take effect), and then enable the SoftDevice.