nRF5X: prevent bootloader from erased after programming

Board : nRF52832_xxac / SDK11/s132  (but not only these have the problem)

After add DFU service in application, we have to program bootloader. In nRFgo , the IROM must be look like this :

but after you compile and program your application again, and open nRFgo next time , you might see :

and that means your bootloader is erased by application.

That's because a mistake of project setting of application



this is project setting of SDK11/ble_app_template

the start point + size = 0x1c000 + 0x64000 = 0x7f000 = the end point.
So, the application is end at 0x7f000 in default.

But in the project setting of SDK 11/bootloader/ dual_bank_dfu_s132

It shows that bootloader start at 0x7a000.

So, if you program application again , it is necessary to erase bootloader for application space.

And the solution I suggest you is :

change application size  0x62000 ->0x5e000

0x1c000+ 0x5d000 = 0x79000 to prevent bootloader from erased after programming


Note:
let the application size smaller than the start point of bootloader for 0x2000 is more stable.

Reference :
https://devzone.nordicsemi.com/question/100609/sdk-12-bootloader-erased-after-programming/