SD+BL+APP dfu only update SD+APP successfully

[_maibi]

SDK: 7.0.2

CHIP: nRF52840

I'm faced with strange dfu behavior.

The dfu SD+BL+APP (softdevice 6.1.1 -> 7.2.0) is working fine which was flashed by j-link.

However, Same package dfu which was flashed by I-DAP is always updated only SD+APP without BL. nothing error. 

I assumed to write different flash data between tools I-DAP and J-Link. But Very strange, these flash data were same. I read back flash data by nrf-connect programmer and compared WinMerge.

I think it make a sense that same flash data is same behavior in this level. but actually It isn't.

Could this happen because of the use of register that I did not think of?

Is there any possibility of only updating SD+APP without Bl ?

[Einar Thorsrud]

Hi,

SoftDevice updates without a simultaneous bootloader update is only supported if the SoftDevice has the same major version. If you update to a new SoftDevice version, a bootloader update is also enforced. This is don so in order to avoid bricking devices in the filed. Specifically, if you upgrade to SoftDevice which is not compatible with the old bootloader, this would render the device non-upgradable in the future, and is why this is prevented. This check is done by the bootloader, so you will not see this when programming with a debugger. I suspect you will see issues if you try to do a update via DFU again afterwards though, as you have an incompatible bootloader and SoftDevice.

[_maibi]

Hi, Einar Thorsrud.

Einar Thorsrud said:

If you update to a new SoftDevice version, a bootloader update is also enforced. This is don so in order to avoid bricking devices in the filed. Specifically, if you upgrade to SoftDevice which is not compatible with the old bootloader, this would render the device non-upgradable in the future, and is why this is prevented.

Yeah, I know this. so, It is blocked to generate sd+app dfu package.

However, I'm not asking for it, it's happening right now. 

It is very strange behavior. I came up with an idea that the device which is failed to update sd+bl+app will be updated for only bootloader dfu package. 

I'll try it tomorrow and let you know.