Why is PSTORAGE_NUM_OF_PAGES in DFU is by default set to 2?

[Arjun]

Hi,

I am wondering why PSTORAGE_NUM_OF_PAGES is by default set to 2 in the DFU project.

From what I understand the pstorage_raw.c module is used to update bootloader settings data during OTA. And we only allocate 1 page for this. I tried setting PSTORAGE_NUM_OF_PAGES to 1 and the pstorage_register() returns NRF_ERROR_NO_MEM because m_next_app_instance has changed to 1.

I do not understand how m_next_app_instance changes to 1 since in pstorage_init we initialize it to 0. Could you let me know if I am missing something that is very trivial.

P.S. We are using SDK version 10 for our development.

Thanks in Advance, Arjun

[bjorn-spockeli]

Hi Arjun,

PSTORAGE_NUM_OF_PAGES is by default set to 2 because you need two application instances, one for the bootloader settings and one for writing/swapping the application firmware image. You register the bootloader settings instance in bootloader_init() and the firmware instance in dfu_init().

-Bjørn

[Arjun]

Hi Bjorn,

Perfect!. That explains it. Thanks for the answer.

[bjorn-spockeli]

Happy to help. I would appreciate if you could mark the answer as correct( clicking the check mark in the circle to the left of the answer).