For boards with a standard 10-pin Serial Wire Debug (SWD) connector or a connector that supports a standard 10-pin flat cable, it is recommended to connect to P19.
Connect the boards as shown in the following figure.
It is recommended to power the external board separately from the DK. The voltage on the external board must match that of the DK. When the DK is powered through the USB connector, the voltage is 3 V.
When pin 3 (SWD0_SELECT) of P19 is connected to GND through the 10-pin flat cable, the interface MCU programs or debugs the target chip on the external board instead of the onboard nRF52840 System on Chip (SoC).
The following figure describes the pinout of the P19 header.
The following table describes the pinout of the P19 connector.
| Pin number | Signal | Description |
|---|---|---|
| 1 | SWD0_VTG | Optional voltage supply to the external target |
| 2 | SWD0_SWDIO | SWD Input/Output line |
| 3 | SWD0_SELECT | Debug out select signal, connect to ground on external board |
| 4 | SWD0_SWDCLK | SWD clock line |
| 5 | GND | Ground |
| 6 | SWD0_SWO | The 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 | SWD0_RESET | Reset line |
Supply power to an external board through P19
- Ensure that SB19 is not shorted.
- To enable power output on P19, short solder bridge SB47.
- Power the DK through the USB connector.