OTA DFU firmware app flashing doesn't work as intended

[Trebor]

Hello,
I want to flash a test application to the nrf52820(on the 52833DK(it supports both 33 and 20) for test purposes. I first flashed the softdevice and the bootloader. Got a private and public key pair created the dfu zip file and tried flashing over my phone with the nrf Connect app. I work with the nrf5sdk. 

The application doesnt appear after flashing OTA.

When I flash the app over cable(how it should look like)

First step: flashing the bootloader + softdevice

This happens after I try to flash the app OTA from my phone:

Theres no error message in the log of the nrf connect app while flashing OTA. Also after flashing the 2 leds turn off and it disappears from the bluetooth list on my phone. I used the secure_bootloader example from the github repo.

[Vidar Berg]

Hello,

The bootloader will only boot the app if it's able to validate the integrity of the applicaiton (see Boot validation modes. Otherwise, it should fall back to DFU mode. It's also strange that you aren't getting any errors during the DFU transfer. Are you able to debug the bootloader to see where the program ends up after the update has finished?

I used the secure_bootloader example from the github repo.

Is this a public repo? We did not host the nRF5 SDK on github so I'm wondering which SDK this bootloader is from and if it has been modified compared to our original version.

Best regards,

Vidar

[Trebor]

Sorry I was wrong it wasn't a public repo it was the .zip from https://www.nordicsemi.com/Products/Development-software/nRF5-SDK/Download?lang=en#infotabs (the offical download)

[Vidar Berg]

No problem, but are you using the latest SDK then and are you able to debug the bootlader to see what happens after DFU has completed? Can you post a screenshot showing the CPU registers?

[Trebor]

I am relatively new to the field so it's hard for me to give you exact details. I dont have any debug hardware. Only my pc with nrf Connect for desktop so I cant really see the CPU registers can I? Is there another way for me to provide further details?

[Vidar Berg]

The DK has an on-board Jlink debugger which is what that allows you to program the chip from the Programmer app. You can also use this to debug your FW from the IDE you're using.  Are you using Segger embedded studio, Keil, or IAR to build your project? 

[Trebor]

I am using armgcc and visual studio code.