UART based DFU works but then the application does not start

[KSV]

I can successfully download an image using nrfutil dfu serial when I use a test image (compiling the bootloader with the Nordic default public key) and the application starts.

I can do the same using nRF Connect Programmer.

I can successfully download an image using nrfutil dfu serial when I generate an image using a generated key, compiling the bootloader with the generated public key.

The download is successful, however the application will not start. The application is the example ble_app_uart_pca10040_s132.

I try to use the nRF Connect Programmer and after programming the application does not start either (SoftDevice (with MBR) and application hex files).

I then created a bootloader settings hex file, thinking this was the problem. But "nrfjprog --program settings.hex --sectorerease" did not help, the application still does not start after download.

I added the bootloader settings hex file while trying the nRF Connect Programmer and this did not help either. (SoftDevice (with MBR), bootloader settings and application hex files).The application still does not start after being programmed.

Ubuntu Linux 16.04.6 LTS

S132 SoftDevice v6.1.1

Nordic SDK v15.3.0

Application: ble_app_uart_pca10040_s132

Bootloader: secure_bootloader_uart_mbr_pca10040_debug

[Hung Bui]

Hi KSV, 

I think the reason why you don't see anything after the image is transferred successfully is that the softdevice was missing. 

The bootloader was created to work with or without the softdevice. So it only requires you to flash the MBR, instead of the bootloader. Have you tried flashing the softdevice before testing ? 

Without the softdevice, the ble_app_uart won't work.