On the nRF9160 DK, there are a few analog switches that are used to connect and disconnect signals to control buttons, switches, and LEDs.
The analog switches select if the LEDs, buttons, and switches should be connected directly to the nRF9160 General-Purpose Input/Output (GPIO) or to an I/O expander. See I/O expander for more information. The switches are controlled by the nRF52840 System on Chip (SoC), which contains firmware from Nordic Semiconductor.
Figure 1. LED switch control
