If your external board has custom connections to programming and debugging pins, you can use the debug output on pin list P20.
Connect the boards as shown in the following figure.
Figure 1. Connecting an external board to P20
It is recommended to power the external board
separately from the DK. The voltage on the external board
must match that of the DK, which is 1.8V when the DK is powered through the USB
connector.When the interface MCU detects the voltage of the external board on pin 3 (VTG) of P20 it programs or debugs the target chip on the external board instead of the onboard nRF5340 System on Chip (SoC).
If it is inconvenient to have a separate
power supply on the external board, the nRF7002 DK can supply power through
pin 2 (VDD) of P20. The connection is shown with a grey
outline in Connecting an external board to P20.
Note: If the interface MCU detects ground on P19 and power on
P20, it programs or debugs the target connected to P19 by
default.
CAUTION:
To avoid damaging your board,
when VDD of nRF7002 DK is connected to the external
board, do not connect a separate power supply to the external
board.
The following figure shows P20 connector pinouts with a description
table.
Figure 2. Debug output connector P20
| Pin number | Signal | Description |
|---|---|---|
| 1 | nRF7002_IOVDD | nRF7002 DK companion IC power domain for current measurement |
| 2 | VDD | Main nRF7002 DK power domain |
| 3 | SWD1_VTG | Voltage supply from the external target |
| 4 | SWD1_SWDIO | Serial Wire Debug (SWD) Data Input/Output |
| 5 | SWD1_SWDCLK | Serial Wire Clock |
| 6 | SWD1_SWO | The Serial Wire Output (SWO) line is not needed for programming and debugging over SWD. |
| 7 | SWD1_RESET | Reset line |
| 8 | N.C. | Not used |
| 9 | VIN 3-5V | Voltage supply |
| 10 | nRF7002_VBAT | nRF7002 DK VBAT power domain for current measurement |
| 11 | VBAT | Main VBAT power domain |
| 12 | VIO_REF | GPIO voltage reference input |
| 13 | BOARD_ID | DK ID resistor |