nRF52-DK (PCA10040 / v3.0.0 / 2022.14) does not enter bootloader mode

[ccattuto]

I have 4 rencet nRF52-DK boards. The sticker on the MCU says "PCA10040 / v3.0.0 / 2022.14). I want to switch them to the DAPLink firmware, and to do so I need them to enter bootloader more. All of the fail to enter bootloader more according to the documented way (holding down the IFBOOT/RESET button while power-cycling or powering up the board). Tested on OSX and Linux, with different USB cables, with VCOM enabled/disabled via JLinkConfig.

Another puzzle: JLinkConfig identifies the board as "nRF5340-DK" instead of nRF52-DK and successfully updates the firmware. JLinkConfig appears to work correctly. The board definitely has an nRF52832 onboard, but it has a "flow control" switch that is not present in the documentation and published schematics/photos of nRF52-DK (and is present in the nRF5340 board, indeed).

Any ideas? This does not happen with older versions of the same board (e.g., PCA10040 / 2.0.0 / 2020.10).

Thanks in advance!

[ketiljo]

Rev 3.0 of the DK's are using a nRF5340 as a debugger. This doesn't have a bootloader mode as the Atmel SAM MCUs used on earlier revisions. 

[ccattuto]

Thanks for your prompt answer. This sounds like a major change for a product such as the nRF52-DK that has been stable for many years. Is this documented anywhere? I would not have purchased these boards had I known that it’s no longer possible to update the MCU firmware (e.g., to DAPLink). Also, this means that Nordic Semiconductor’s own documentation for the nRF52-DK (PDF manuals and web site) does not faithfully reflect the features of the product as sold today, unless I am missing something. Thanks in advance for your comments on this!

[ccattuto]

A related question, thanking you in advance: does the nRF5340 J-Link firmware of the  Rev 3.0 DK support in any way CMSIS-DAP, as advertised by SEGGER  for some of their probes, https://www.segger.com/news/segger-j-link-now-supports-cmsis-dap/ ?

[ketiljo]

No, that's only supported by an external, high speed debugger. 

The change to the nRF5340 as a debugger was done of availability reasons. Unfortunately, the documentation doesn't reflect this yet.

However, since MBED hasn't been supported for quite a while, using other debuggers aren't supported with the current DKs.

[ccattuto]

thanks for your feedback!