The nRF9160 DK has an I/O expander that can optionally be used to interface the LEDs, slide switches, and buttons.
The connection of each component is controlled by the nRF52840 using analog switches (see Switches for buttons and LEDs). The I/O expander can be enabled by the nRF52840. See Switches for I/O expander. When the I/O expander is enabled, the I/O expander is interfaced by the nRF9160 GPIOs shown in the following table.
| Signal | GPIO | Description |
|---|---|---|
| SDA | P0.30 | I2C data line |
| SCL | P0.31 | I2C clock line |
| IOEXP_IRQ | P0.06 | Interrupt line from the I/O expander |
The following table shows the I/O expander connections:
| Component | I/O expander pin |
|---|---|
| LED 1 | I/O_EXP_IO4 |
| LED 2 | I/O_EXP_IO5 |
| LED 3 | I/O_EXP_IO6 |
| LED 4 | I/O_EXP_IO7 |
| Switch 1 | I/O_EXP_IO2 |
| Switch 2 | I/O_EXP_IO3 |
| Button 1 | I/O_EXP_IO0 |
| Button 2 | I/O_EXP_IO1 |
Figure 1. I/O expander
