storing sensor data to flash

[kizhimon]

Hi,

SDK - 17.1.0

I want to store my sensor data to the internal flash memory of nRF52810 for a long time. I have some questions here:

1. The data sheet says the flash memory is 192 KB for nRF52810. How much memory from 192 kB will be available for user to store the data ? Please note that I am not using softdevice
2. Which interface should I use and why ? (FDS or FSTORAGE)

[dgerman]

1 Flash memory holds your code, initialization constants, nRF code modules (like FlashDataStorage code ).

You need to link all these pieces and look at the load map to see what they have taken then you can determine how many PAGES you can allocate for FDS. The symbol __exide_end is the end of the used flash. Allocate the next higher page address ( xx000) as the  start address for .storage_flash section in the the link commands. Better to leave an extra page for code growth. 

2 FDS supports variable length records assigned to files. each record uses 3 words of overhead (including the 2 byte record key and 2 byte fileID) . If your application expects to add/update/delete data FDS will manage those things for you. If you have many many small records (relative to the 3 words header) you should consider blocking them into almost page size records.(2 additional words of overhead are in each page).

FSTORAGE simply uses pages.

[Hung Bui]

Hi Kizhimon, 

1. It depends on your application flash size. The more size the application occupy the less flash you have for storing user data. 

2.  FDS is a simple file system when the fstorage is simply a flash library. The fds uses fstorage as the backend.  Please read the documentation of fds. 

[kizhimon]

Thank you for your answers.

1) How can one know that how much flash size is the application is consuming ? Where and how to check ? 

[dgerman]

look at the load map

[Hung Bui]

After you compile you should have the information about the flash size.
Which compiler do you use ? 
You can also use arm-none-eabi-size to read the .elf (or. hex) file to get the size. 

arm-none-eabi-size.exe yourfile.elf