Cannot program board with NRF52840-dk using P19 connector.


I would like to use the P19 connector present on the NRF52840-dk (3.0.2) for programming/debugging my custom board, but unfortunately it doesn't seem to work.

For convenience sake I bridged the SB47 solder bridge, which should supply my board with power.  I verified that the power works.

When I try to program it, the development board gets programmed instead!  At first I thought it might be an issue with my custom board, luckily I have also the dongle board and soldered a 10-pin connector to the footprint at the bottom.  I can observe the exact same behavior on the dongle.

In the documentation there is explained that is should not be possible to program the onboard chip while SB47 is bridged, but maybe revision 3.0.2 has different behavior. I could not find any documentation for the newer devboards.

Is there something I may have missed?

Thank you and kind regards.