Need some help with confusion about flash locations and size (nrf52832 + s132 6.1.1 softdevice)

[Jur]

Hi all,

Currently I am working on my first project with the nrf52832. All is going quite well, but I would really like some help with my flash layout, basically I got some confusion about the following:

Based on this post I figured my flash start position is at 0x26000 which is 155.648 in decimal. Now the nrf52832 which I am using has 256kb of flash memory, does this mean I only have (256 - 155 =) 101kb left for the firmware? My firmware is already bigger than that:

$ du -sh _build/nrfapp.bin
168K	_build/nrfapp.bin

I can flash it without problems and it works fine though. Am I working with wrong numbers?
This is how I would like the flash layout to look:

Content	Start Address	Size (bytes)
Firmware	0x26000	175000
AppData	0x50B98	4096

Could someone help me clear my confusion?

Thanks a lot!

UPDATE: After writing this post I suddenly found a post where people recommended looking at the nRFConnect programmer. I figured my chip actually has 512kb of flash! I would still like to know if my approach is correct. Also, why does it look like this?:

[Einar Thorsrud]

Hi,

Your calculations are correct. And using nRF Connect programmer for visualizing the memory layout quickly is a good idea.

nRF Connect Programmer does not really know what is in the flash, so it makes assumptions. All the green sections are seen as application or application data, and the reason they are not consecutive is that there is chunks of erased flash in between for some reason. Perhaps you initialize a lot of FDS pages, or something else? What does your hex file(s) look like if you add them to the programmer app and look at them on the right-side panel? Do you still see all these chunks? If not, then this is because your firmware writes to that flash regions, or because of some "leftovers" from before if you have not done a full chip erase.

[Turbo J]

Jur said:

does this mean I only have (256 - 155 =) 101kb left for the firmware?

Would be correct if you had the 256KB flash variant (NRF52832_XXAB).The _XXAA variant has 512KB flash.

That is why there are smaller softdevices with less features available - the S132 is "too fat" for some application and chip variants.

I don't use desktop nRFConnect app, thus cannot say anything about the graphics.

[Jur]

Thanks a lot for the reply. I'm glad my calculations are correct. It seems like I was mainly confused because of the incorrect flash size. You are correct, they are leftover FDS pages!

[Jur]

Thanks a lot for taking the time to reply! Sounds interesting, I will take a look at the different soft devices aswell, thanks for the suggestion!