Using the DFU SDK 12.1 with a BLE command to jump to 'bootloader' works every other time with nordic connect app

[sananth]

We have been using the DFU that came with the sdk 12.1 with a modification (essentially removing the button from the DFU code). We currently send an application command that will tell the code to 'jump' to the bootloader. This works great. Once the app command is reeived the device begins advertising 'DFUTarg' I use the nrf connect android app to load the .zip file.

It works the first time, and every odd number time after; hence the second time of jumping back to the bootloader it will appear as if the app was loaded properly and nrf conenct will state the app was successfully loaded but when I scan the device still advertises as DFUTarg. If I try to load again, it will say successfully loaded and will advertise with our custom name.

We have the watchdog timer enabled in the application and following some other posts I added NRF_WDT->RR[0] = WDT_RR_RR_Reload; to the wait_for_event loop in the DFU to pet the dog.

Any suggestions?

[bjorn-spockeli]

If you debug the bootloader after the DFU, does it reach nrf_bootloader_app_start in nrf_dfu.c (should be at line 143 in nrf_dfu.c)? If so, could you try to debug the application? Lastly, could you read back the flash after a failed DFU to a file and attach it to the question? You can read back the flash and store it to a file using the following command.

nrfjprog -f nrf52 --memrd 0x00000000 --n 524288 >> hex_dump.txt