nRF52 DK v1.2.x

Debug output

The nRF52 DK supports programming and debugging nRF51 and nRF52 devices mounted on external boards. To debug an external board with SEGGER J-Link OB IF, connect to the Debug out connector (P19) with a 10-pin cable.

Figure 1. Debug output connector
Debug input connections (P19 and P20) on nRF52 DK
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 nRF52832.
Note: The voltage supported by external debugging/programming is 3.0 V.
You can also use P20 as a debug out connection to program shield mounted targets. For the Debug out header (P19), the interface MCU will detect the supply voltage on the mounted shield and program/debug the shield target.

If the interface MCU detects target power on both P19 and P20, it will by default program/debug the target connected to P19.