The nRF52840 DK (Development Kit) board supports programming and debugging
external boards with nRF51 or nRF52 System on Chip (SoC)s. To debug an external board
with SEGGER J-Link OB IF, connect to the Debug out connector (P19) with a 10-pin
When the external board is powered, the interface MCU will detect the supply voltage of the
board and program/debug the target chip on the external board instead of the onboard nRF52840
Note: The voltage supported by external debugging/programming
is VDD voltage. Normally, this is 3 V when running from USB, but if the onboard nRF52840 SoC is
supplied from either USB or Li-Ion, the nRF power source switch (SW9) is in either
Li-Po or USB position, and VDD can be set by the nRF52840 firmware. Make sure the voltage level
of the external board matches the VDD of the nRF52840 DK.
can also use P20 as a debug out connection to program shield-mounted targets. For both
P19 and P20, the interface MCU will detect the supply voltage on the
mounted shield and program/debug the target.
If the interface MCU detects target power on both P19 and P20, it will by
default program/debug the target connected to P19.
If it is inconvenient to have a separate power supply on the external board, the nRF52840
DK board can supply power through the Debug out connector
(P19). To enable this, short solder bridge SB47. Note that as long as
SB47 is shorted, it is not possible to program the onboard nRF52840 SoC even if the
external board is unplugged.