Partial Erase feature of NVMC

RE: Partial Erase feature of NVMC

Ankit Modi — Thu, 13 Jul 2023 14:52:00 GMT

Thanks for responding to my query and solving the confusion.

Thanks again.

RE: Partial Erase feature of NVMC

Jørgen Holmefjord — Thu, 13 Jul 2023 14:48:20 GMT

As you correctly mentions, the CPU is halted during flash write/erase operations, this is needed as the CPU executes code from flash, and this can't happen at the same time as flash is written/erased.

It is not possible to configure the partial flash erase time slice lower than 1ms, so it would not be possible to trigger the timer exactly at 1ms intervals. There will also be some overhead in time for switching to the timer handler.

RE: Partial Erase feature of NVMC

Ankit Modi — Thu, 13 Jul 2023 14:34:16 GMT

Hi Jørgen Holmefjord,

Thanks for responding.

I am going to use storage partition on the internal flash to store some data using LittleFS File System.

It was observed that during the file write/erase operation on the internal flash, the CPU halts. During this erase process also, I would like to have a 1 milli-second Timer running. So, I am going to use Partial Erase Functionality of NVMC. But as per the tests, when SOC_FLASH_NRF_PARTIAL_ERASE_MS=1, this timer functionality is affected, the Timer Callback function is called after some delay of 300 uSec up to 1.5 mSec.

So, is there any configuration that can be used to achieve this?

FYI, I also tried Zero Latency Interrupts configuration for Timer. The results are still the same.

Thanks again.

RE: Partial Erase feature of NVMC

Jørgen Holmefjord — Thu, 13 Jul 2023 13:46:27 GMT

Hi,

As far as I can see, there is no HW limitations preventing you from setting ERASEPAGEPARTIALCFG to 1ms, but according to the nRF Connect SDK Developers, they observed some issues when it was set to 1ms. If it works at 1ms on your end, it should be fine to use this, but I would recommend sticking with the minimum value stated in the comment.

[quote user=""]

Can anybody give how to configure this value and what value can be used as per the following use case:

Timer1 is to be used as Counter and the Timer Callback needs to be called every 1 ms irrespective of any other functionality.

[/quote]

Not sure I understand what you are asking for here. Are you planning to perform the flash erase manually in the application? The config is intended for use with the soc_flash driver. It is not possible to set the config below 1ms, so it would not be possible to erase flash pages if you require the timer callback to be called exactly every 1ms.

Best regards,
Jørgen