For boards with a standard 10-pin Serial Wire Debug (SWD) connector or a connector that supports a standard 10-pin flat cable, connection to P19 is recommended.
Connect the boards as shown in the following figure.
It is recommended to power the external board separately from the DK. The voltage of the SWD interface on the external board must match that of the DK. The default voltage is 1.8 V.
When the interface MCU detects GND of the external board on pin 3 (SELECT) of P19, it programs or debugs the target chip on the external board instead of the onboard nRF9151 System in Package (SiP).
The following figure shows the P19 pinout.
The following table shows the P19 pinout.
| Pin number | Signal | Description |
|---|---|---|
| 1 | EXT_VDD | By default not connected, for configuration see SB15 and SB16 in Solder bridge configuration |
| 2 | SWDIO | SWD data input/output |
| 3 | SELECT | Select pin for the interface MCU, should be connected to GND on the external board |
| 4 | SWDCLK | Serial wire clock line |
| 5 | GND | Ground |
| 6 | SWO | Serial Wire Output (SWO) line is not used for programming and debugging over SWD |
| 7 | N.C. | Not used |
| 8 | N.C. | Not used |
| 9 | N.C. | Not used |
| 10 | RESET | Reset line |
If you do not have a separate power supply on the external board connected to the Debug out connector P19, the external board can be powered from the onboard DK regulator as follows:
- Short solder bridge SB16 to enable power output on P19.
- Power the DK through the USB connector.