Hi Rodrigo,

GPREGRET is general purpose retention register in the SoC, which only retains value across warm resets.

Refer to http://infocenter.nordicsemi.com/topic/com.nordic.infocenter.nrf52840.ps/power.html?cp=2_0_0_4_2_5_7#concept_res_behav

The value is lost for reset behaviours like watchdog reset, pin reset, etc. Do not use this register in applications requiring persistent storage.

Regards,

Vinayak

On 21 May 2018, at 05:16, Rodrigo Peixoto <rodrigopex@...> wrote:

Hi fellows, I am developing an application that counts pulses from a source. I need this system to be the lowest power possible. I was wondering if I could use the GPREGRET register do store this counting. Can I? My concern is that, as the documentation says, the DFU feature from Nordic also uses that retention register. Is the mcumgr + MCUBoot (FOTA) using that as well? Note that I would like to use the FOTA feature in this project.

By the way, I took a look at the Zephyr repo and the only mentions to this register is on the NRFX Nordic hal. Is that a good signal?

Thank you. Best regards, Rodrigo Peixoto.

On 21 May 2018, at 05:16, Rodrigo Peixoto <rodrigopex@...> wrote:

Hi fellows, I am developing an application that counts pulses from a source. I need this system to be the lowest power possible. I was wondering if I could use the GPREGRET register do store this counting. Can I? My concern is that, as the documentation says, the DFU feature from Nordic also uses that retention register. Is the mcumgr + MCUBoot (FOTA) using that as well? Note that I would like to use the FOTA feature in this project.

By the way, I took a look at the Zephyr repo and the only mentions to this register is on the NRFX Nordic hal. Is that a good signal?

Thank you. Best regards, Rodrigo Peixoto.

Hi Rodrigo,

I am not an expert on persistent storage, but if your system undergoes frequent cold resets then the system will need to write to flash. You may refer to flash API, circular buffer or filesystem implementations in Zephyr.

More details to help you could be provided by Andrzej (cc-ed).

Regards,

Vinayak

On 21 May 2018, at 05:28, Chettimada, Vinayak Kariappa <vinayak.kariappa.chettimada@nordicsemi.no> wrote:

Hi Rodrigo,

GPREGRET is general purpose retention register in the SoC, which only retains value across warm resets.

Refer to http://infocenter.nordicsemi.com/topic/com.nordic.infocenter.nrf52840.ps/power.html?cp=2_0_0_4_2_5_7#concept_res_behav

The value is lost for reset behaviours like watchdog reset, pin reset, etc. Do not use this register in applications requiring persistent storage.

Regards,

Vinayak

On 21 May 2018, at 05:16, Rodrigo Peixoto <rodrigopex@...> wrote:

Hi fellows, I am developing an application that counts pulses from a source. I need this system to be the lowest power possible. I was wondering if I could use the GPREGRET register do store this counting. Can I? My concern is that, as the documentation says, the DFU feature from Nordic also uses that retention register. Is the mcumgr + MCUBoot (FOTA) using that as well? Note that I would like to use the FOTA feature in this project.

By the way, I took a look at the Zephyr repo and the only mentions to this register is on the NRFX Nordic hal. Is that a good signal?

Thank you. Best regards, Rodrigo Peixoto.

On 21 May 2018, at 05:28, Chettimada, Vinayak Kariappa <vinayak.kariappa.chettimada@...> wrote:

Hi Rodrigo,

GPREGRET is general purpose retention register in the SoC, which only retains value across warm resets.

Refer to http://infocenter.nordicsemi.com/topic/com.nordic.infocenter.nrf52840.ps/power.html?cp=2_0_0_4_2_5_7#concept_res_behav

The value is lost for reset behaviours like watchdog reset, pin reset, etc. Do not use this register in applications requiring persistent storage.

Regards,

Vinayak

On 21 May 2018, at 05:16, Rodrigo Peixoto <rodrigopex@...> wrote:

Hi fellows, I am developing an application that counts pulses from a source. I need this system to be the lowest power possible. I was wondering if I could use the GPREGRET register do store this counting. Can I? My concern is that, as the documentation says, the DFU feature from Nordic also uses that retention register. Is the mcumgr + MCUBoot (FOTA) using that as well? Note that I would like to use the FOTA feature in this project.

By the way, I took a look at the Zephyr repo and the only mentions to this register is on the NRFX Nordic hal. Is that a good signal?

Thank you. Best regards, Rodrigo Peixoto.