How can I use DFU with peripherals/blinky?

Question

I have flashed DFU OTA bootlaoder to my nRF82540 DK. (C:
RF5_SDK_17.0.2_d674dde\examples\dfu\secure_bootloader\pca10056_s140_ble_debug) 
 It shows the two LEDs 1 and 2. 
 I can flash ble_blinky. It shows LEDs 1 and 3 when flashing. It works. 
 BUT So I can get some understanding of what is going on I would like to flash plain old blink to the device using the OTA. 
 I change the blink *.ld file from 
 MEMORY { FLASH (rx) : ORIGIN = 0x1000, LENGTH = 0xff000 RAM (rwx) : ORIGIN = 0x20000008, LENGTH = 0x3fff8 } 
 to 
 MEMORY { FLASH (rx) : ORIGIN = 0x27000, LENGTH = 0xff000 RAM (rwx) : ORIGIN = 0x20000008, LENGTH = 0x3fff8 } 
 
 So that the application is now above the softdevice. It all looks fine, but it doesn't work. 
 
 So how do things work. I'm assuming that somewhere there is a jump to the address where the blinky app is loaded (at 0x27000?) and then blinky runs. 
 I'm guessing that my ignorance is going to give me a heart attack at some point. 
 Is there a document that explains for newbies how all of this hangs together? 
 Gordon 
 (In my research I've seen references to a define for APPLICATION_START_ADDRESS or something similar, but I can't find it. It may have been an old sdk?) 
 Here is my memory map

gfmoore · Answer

Yes I have tried reading this, but sometimes it is very opaque for a newbie. For instance, the second sentence: 
 If we simply program the application with the bootloader using the programmer... 
 er? 
 
 Anyway, for anyone else the answer to the first part is that it seems that if you keep the application-version the same or greater then no problem. I'm not really sure that I then need the --debug-mode. It's hard to understand what the 'help' is saying? 
 
 I think Nordic need to take a look at how they can better help newbies to this embedded stuff as often there are assumptions being made as to how much prior knowledge a person has. The documentation is written for people who already seem to know stuff! rather than for people who don't. 
 When new Nordic employees arrive do they get training or does Nordic assume that people already know stuff? 
 
 Anyway, thanks. Moving on to buttonless. That will be a few weeks out of my life then... ;) 
 Gordon