Combining NUS and Buttonless DFU

[uDog]

Hi, 

I am relatively new with ble and nordic development. I am working with the nus service for communicating but now i also want to have ota firmware update. I am trying to combine buttonless dfu with nus service. I followed this tutorial https://www.u-blox.com/sites/default/files/Add-NordicSemiconductorDFU-to-SDKexample_AppNote_%28UBX-19050198%29.pdf. Nus and dfu service both show up but when i start the dfu it gets stuck in the dfu cycle. And the new application is not updated. It keeps cycling between starting bootloader, starting uploader and disconnecting. I am doing buttonless dfu from my android phone. 

Instead, now i am starting with the dfu buttonless application and trying to integrate nus into it. I have copied the important bits from the nus app and trying to compile it. I am using keil for development. I get the following errors 

.\_build\nrf52840_xxaa.axf: Error: L6218E: Undefined symbol app_uart_get (referred from main.o).
.\_build\nrf52840_xxaa.axf: Error: L6218E: Undefined symbol app_uart_init (referred from main.o).
.\_build\nrf52840_xxaa.axf: Error: L6218E: Undefined symbol app_uart_put (referred from main.o).
.\_build\nrf52840_xxaa.axf: Error: L6218E: Undefined symbol ble_nus_data_send (referred from main.o).
.\_build\nrf52840_xxaa.axf: Error: L6218E: Undefined symbol ble_nus_init (referred from main.o).
.\_build\nrf52840_xxaa.axf: Error: L6218E: Undefined symbol ble_nus_on_ble_evt (referred from main.o).
Not enough information to list image symbols.
Not enough information to list load addresses in the image map.

I have included files in to the project from component folder (libraries/ble_service) required for nus. I have also added the header files to include paths for the c/c++ and asm tab in keil but i still can't compile it. 

This is screen recording of what's happening when i try to start the dfu.  I can see that i get a message from the remote device with OpCode=1,Status=1 . 

https://streamable.com/hgfy7

I would really appreciate it if anyone you can point out what i am doing wrong in anyone of these approaches. 

[uDog]

I was able to  make it work. I used the code from the tutorial but added peer manager to it as well. Enabled peer manager and fstorage inside the sdk file.  

I think the problem was with the bootlader. To begin i was compiling the bootloader myself from the code but i ended up using the "secure bootloader without bonds" hex file.