nRF9161 DK v0.9.1

Programming a board with custom connections

If your external board has custom connections for programming and debugging pins, you can use the debug output on P20.

Connect the boards as shown in the following figure.

Figure 1. Connecting a custom board to P20
Connecting a custom 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 1.8 V or 3.0 V depending on the position of SW9 when the DK is powered through the USB connector.

When the interface MCU detects the voltage of the external board on pin 3 (SWD1_SELECT) of P20, it programs or debugs the target chip on the external board instead of the onboard nRF9161 System in Package (SiP).

Note: If the interface MCU detects power on P19 and P20, it programs or debugs the target connected to P19 by default.

If there is no separate power supply on the external board, the nRF9161 DK can supply power through pin 2 (VDD) of P20.

To avoid damaging your board, when VDD of nRF9161 DK is connected to the external board, do not connect a separate power supply to the external board.

The following figure and table show the P20 connector pinouts.

Figure 2. Debug output connector P20
Debug output connector P20
Table 1. Pinout of connector P20 for programming external targets
Pin number Signal Description
2 VDD Main nRF9161 DK GPIO level power domain
3 VTG Voltage supply from the external target, used as a select pin for the interface MCU to enable this port
4 SWDIO Serial Wire Debug (SWD) Data line
5 SWDCLK Serial wire clock line
6 SWO The Serial Wire Output (SWO) line is not used for programming and debugging over SWD
7 RESET Reset line
9 VIN 5V
10 VDD_nRF nRF9161 SiP power domain
11 VDD_5V
12 VIO_REF GPIO voltage reference input
13 ID ID resistor to ground