The performance measurement mode can be selected by moving the IFMCU DISCONN switch (SW6) to the right position, which disconnects the interface MCU from the nRF9160 System in Package (SiP) using analog switches.
This is done to isolate the nRF9160 SiP as much as possible and can be of use when measuring currents on low-power applications.
The Development Kit (DK) detects if there is a Universal Serial Bus (USB)USB cable plugged in (see USB detect) and will disconnect and power down the interface MCU when another supply than the USB is used. If the USB connector is used for power supply only (USB battery back) you can also disable the interface MCU using SW6.
USB detect and SW6 also control the routing of the RESET signal from the RESET button (SW5). Normally, it is routed through the interface MCU, but if that is disabled, the reset button will be routed directly to the nRF9160 SiP.
There are also a number of other reset routing options available through the use of solder bridges:
- When the interface MCU is disconnected, the RESET button is connected to pin 32 (nRESET) of the nRF9160 SiP. The RESET button can be disconnected from the nRF9160 SiP by cutting SB15.
- When the interface MCU is disconnected, shorting SB18 will connect the RESET pin of the Arduino interface to the reset pin of the nRF9160 SiP.
- When the interface MCU is connected, shorting SB19 will connect the RESET pin of the Arduino interface to the BOOT input of the interface MCU.
- Shorting SB16 will connect the RESET pin of the Arduino interface to the RESET button.
- Shorting SB17 will connect the RESET pin of the Arduino interface to the nRESET pin of the nRF9160 SiP.
- When the interface MCU is disconnected, shorting SB21 will connect the RESET pin of the nRF52840 to the RESET button.
- Shorting SB22 will connect the RESET pin of the nRF52840 to the RESET button.