pstorage_store and pstorage_update execution time

[ting²]

Hello

Where can I find operating characteristics of pstorage_store and pstorage_update?

Actually, I observe that about 100 ms are needed to update 4 bytes data. For me, it seems a little long for an internal memory access.

Is it normal ?

Thanks

[Stefan Birnir Sverrisson]

Hi

According to the nRF51822 PS v3.1 table 61, flash write operation takes up to 46.3us and flash erase takes up to 22.3ms. Flash erase can be performed on minimum a whole page, i.e. 1024 bytes. Flash write can be done on minimum one word, i.e. 4 bytes.

What happens when you issue an pstorage_update is as follows:

• The so called swap page is erased
• The data of the updated page that is not being updated is written to the swap page
• The page is erased
• The update data is written to the flash page
• The the remainder of the page that is not to be updated is written back to the page from the swap page

So the pstorage_update command actually contains at least two flash erase commands and multiple flash write commands, which explains how long it takes.

[ting²]

Thank you very much!