nRF5340-DK won't connect to external hardware

[PatGries]

I have an "old" nRF5340-DK which I use to program an external board I am developing.  I have no problem with the J-Link/SWD connection to my external hardware using the J19 Debug Out port.  However, I recently purchased 2 more nRF5340-DK boards and neither of these "new" ones would connect to the external hardware.  Upon closer inspection I found a subtle change.  Near J19 is a solder bridge SB47 which all 3 boards have and is documented in the user guide (https://infocenter.nordicsemi.com/pdf/nRF5340_DK_User_Guide_20210304.pdf) in section 4.13.  However, the 2 "new" boards also have SB19 which is not documented.  I took a chance and shorted SB19 and then I could connect to my external hardware.  Is this the correct approach?

"old" nRF5340-DK:

• PCA10095
• 0.10.0
• 2020.38
• 960155940

"new" nRF5340-DKs:

• PCA10095
• 2.0.0
• 2021.40
• 1050034677  &  1050082526

[Simonr]

Hi

What voltage does the external board you're using run at? Please note that the nRF53 DK only supports debugging at 3V, and that it should work without soldering SB19. The SB19 has a different use in revision 2 than the older nRF5340 DKs, which is why one is soldered and one is open by default.

Best regards,

Simon

[PatGries]

The external board is running at 1.8V.

[Simonr]

Hi Patrick

All our DKs are designed for programming external targets at 3.0V VDD. You may be able to program at other voltages but this has not been tested by us and we can't guarantee or recommend that you do this, or make alterations to the DK to make it work. So please note that this is not a defined or intended behavior on your side.

Best regards,

Simon