The nRF9161 DK has four LEDs and four buttons for user interaction. By default, they are connected to the nRF9161 General-Purpose Input/Output (GPIO)s as shown in the following table.
| Part | GPIO |
|---|---|
| LED 1 | P0.00 |
| LED 2 | P0.01 |
| LED 3 | P0.04 |
| LED 4 | P0.05 |
| Button 1 | P0.08 |
| Button 2 | P0.09 |
| Button 3 | P0.18/AIN5 |
| Button 4 | P0.19/AIN6 |
To change default nRF9161 GPIO connections, see Board control
Any LED or button can optionally be routed to an I/O expander. For more information, see I/O expander.
The buttons are active low, meaning that the input is connected to ground when the buttons are pushed. They have no external pull-up resistor, and therefore the P0.08, P0.09, P0.18, and P0.19 pins must be configured as an input with an internal pull-up resistor.
The LEDs are active high, meaning that writing a logical one (1) to the output pin illuminates the LED. The nRF9161 GPIOs control power transistors, and the LEDs are fed from a separate 3.0 V domain. Therefore, LED current is not drawn from nRF9161 GPIOs or the nRF9161 supply.
The following figures show the buttons and LEDs
