sd_flash_page_erase() time execution on nRF52840

[era]

Hi!

We develop our product on nRF52840 using S113 softdevice, version 7.0.1. From time to time, we need to erase some part of flash, so we use sd_flash_page_erase() function. We measured time execution of this function and it usually takes about 50 us to be executed.

Also, there is an information in nRF52840 documentation that page erase takes 85 ms maximum.
https://infocenter.nordicsemi.com/index.jsp?topic=%2Fps_nrf52840%2Fnvmc.html

Does this function only schedule page erase, which is executed later in smaller parts? Is there any risk, that this function call would take much longer (e.g. 85 ms for whole page erase).

Best regards,
Michal

[Turbo J]

era said:

We measured time execution of this function and it usually takes about 50 us to be executed.

Yes, this function does not actually erase a page. It just schedules an erase during the next available radio time slot.

Which may be much later than anticipated in situations with very high radio usage. The application will be informed (via SD event) when the page erase transaction finshed. This can take significantly more time than 85 ms.