The four buttons and four LEDs on the nRF52840 DK are connected to dedicated GPIOs on the nRF52840 System on Chip (SoC).
| Part | GPIO | GPIO alternative | Solder bridge |
|---|---|---|---|
| Button 1 | P0.11 | P1.07 | - |
| Button 2 | P0.12 | P1.08 | - |
| Button 3 | P0.24 | - | |
| Button 4 | P0.25 | - | |
| LED 1 | P0.13 | SB5 | |
| LED 2 | P0.14 | SB6 | |
| LED 3 | P0.15 | SB7 | |
| LED 4 | P0.16 | SB8 |
If P0.13–P0.16 are needed elsewhere, the LEDs can be disconnected by cutting the short on SB5–SB8. See the following figure for more information.
Since P0.11 and P0.12 are used as part of the Trace functionality, BUTTON 1 and BUTTON 2 can be moved to alternative GPIOs. For more information, see Debug input and trace.
The buttons are active low, which means that input is connected to ground when the button is activated. The buttons do not have an external pull-up resistor, so the P0.11, P0.12, P0.24, and P0.25 pins must be configured as input with an internal pull-up resistor to use the buttons.
The LEDs are active low, which means that writing a logical zero (0) to the output pin turns on the LED.