A problem from experimental -- DFU cover application code in nrf52840 dongle

[Di-sheng]

Hi There

I did 2 experimental for recovering boot-loader of nrf52840 dongle by download dfu (nRF5_SDK_16.0.0_98a08e2\examples\dfu\open_boot-loader\pca10059_usb_debug\ses\open_bootloader_usb_mbr_pca10059_debug.emProject). The difference of the 2 experimental is that the dongle have been downloaded difference application code befor it be downloaded the dfu. one of them is ble_app_blinky_pca10059_s140 (nRF5_SDK_16.0.0_98a08e2\examples\ble_peripheral\ble_app_blinky\pca10059\s140\ses), and other one is light-switch_sever_pca10059(nrf5_SDK_for_Mesh_v4.0.0_src\examples\light_switch\server for pca10059).

SES + DK were used for the experimental; the dfu project is "open_bootloader_usb_mbr_pca10059_debug" which come from "nRF5_SDK_16.0.0_98a08e2\examples\dfu\open_bootloader\pca10059_usb_debug\ses".

Result: The application code of ble_app_blinky_pca10059_s140  still work very well, after  the dfu be downloaded

             The application code of  light-switch_sever_pca10059  stop to work, after  the dfu be downloaded.

Based on my understanding of Boot-loader, I don't think downloading DFU code for recovering boor-loader of dongle should affect any existing application code for any chip.

Q1 :  What is the reason about those result above experimental, Is there any wrong in the experimental?

Q2: How I can avoid  the dfu cover application code when the application code be downloaded first? 

Q3: If the DK can be operated by nRF Connect for PC tools, when  J3 USB be used and DFU be downloaded ?

Q4: Why it  do not pass building that the dfu project locate at "nRF5_SDK_16.0.0_98a08e2\examples\dfu\open_bootloader\pca10059_usb\ses"?

Q5: Is the  dfu of "open_bootloader_usb_mbr_pca10059_debug" correct without any limite?

Thanks,

Di-Sheng

[Hung Bui]

Hi again Dison, 

As I may have already explained to you in earlier cases, the limitation of the bootloader on the dongle is that it doesn't support chip erasing and only support application/softdevice/bootloader update. 
This mean any application data stored on the board will stay after DFU update. This applied for the data that supposed to store provisioning data. This could be the reason why the light switch example won't work when you DFU update it.  

To solve this, you need to erase the board using the SWD interface. 

I wouldn't suggest to use the nRF52840 dongle as the development platform. You should better develop on nRF52840 DK and after the firmware ready you can flash/DFU the firmware on the dongle and test in the field. 

[Di-sheng]

Hi Hung Bui

I got it.

Thanks,

B,Rs

Di-Sheng