PCA10056 JLINK OB software missing

[kgislason]

I am experiencing strange behavior on the PCA10056. I have two boards now in the same state, both were working fine before starting work on the Secure DFU (uart). The following steps got the boards into this mode:

1. Erase all user code from the device 
2. Program using nrfjprog and the hex image dfu\secure_dfu_test_images\uart\nrf52840\bootloader_secure_uart_debug_without_bonds_mbr.hex
3. During testing the board was put into bootloader mode by holding the BOOT/RESET button and powering on the board. LED5 started blinking.
4. The removable storage drive BOOTLOADER disappears after approx 2-3 seconds from Windows, LED5 keeps blinking.

On powercycle the board does not seem to do anything, there is nothing on LED5 and JLINK OB does not work. By holding the BOOT/RESET button and switching on power again the LED5 starts blinking but BOOTLOADER drive disappears right away.

I have tested nrfjprog -i and JLINK Commander with no JLINK found. I can flash the device again using the mbed image (nrf5x_atsam3u2c_if_mbed_V0221_11012017.bin) if I am quick before the BOOTLOADER drive disappears. However I cannot flash JLINK OB (J-Link OB-SAM3U128-V2-NordicSemi 170724.bin) as the file is 108kb and the partition says it has 104kb free before Windows un-mounts the partition. I can't seem to be able to restore the JLINK OB software to the board.

Any suggestions appreciated!

Additional info on the HW:

• Development kit: PCA10056, 0.11.0, 2018.3
• nRF5 SDK 15.1.0
• Already tested the steps described here with no luck. I can't measure any voltage on the header pins (VDD, 5V, etc)
• Board is powered using USB through J2 (Power source is VDD, SW6: Default, SW10: Off, SW7: Def, SW8: ON)
• Working on Windows 10 machine with the newest installation of the Nordic Tools + JLINK software.

[tesc]

Hi,

It seems there is a misunderstanding here regarding two separate bootloaders and what is what.

First, there is our DFU bootloader, which is a piece of firmware that you put on the nRF5x SoC and that is responsible for performing firmware upgrades without the need of an external programmer.

Second, there is the interface MCU on our DKs, which in fact is an external programmer. (Although it is located on the board, it is external to the nRF.) This external programmer can itself be upgraded by entering a bootloader mode, and this is the bootloader mode that you trigger when pressing BOOT/RESET when powering the DK. (I.e. the bootloader that you see is that of the programmer, and has nothing to do with whatever happens to be on the nRF.)

There are known issues with this external programmer's bootloader mode, because it mounts what looks like a shared folder. Other applications such as Dropbox or image albums may see the newly mounted shared folder and think that they can do something with its content. Make sure not to select anything and not to close the popups from those applications. That way you should be able to use the folder yourself (as described in step 4 of the list you referred to.)

Regards,
Terje

[kgislason]

Hi tesc, 

Thanks for your reply. Dropbox was the culprit for the issue, after leaving the window open the mount point stayed and I could flash the JLINK OB software again.