The nRF528540 Dongle is equipped with a green LED (LD1), a multicolor RGB LED (LD2), a user configurable button (SW1), and a reset button (SW2).
The LEDs and buttons are connected to dedicated I/Os on the nRF52840 SoC.
Figure 1. nRF52840 Dongle buttons and LEDs
| Part | Description | GPIO |
|---|---|---|
| SW1 | Button | P1.06 |
| SW2 | Reset | P0.181 |
| LD1 | Green | P0.06 |
| LD2 | Red | P0.08 |
| LD2 | Green | P1.09 |
| LD2 | Blue | P0.12 |
The buttons are active low, which means that the input will be connected to ground when the button is activated. The SW1 button has no external pull-up resistor, but the reset button (SW2) has a 10 k pull-up resistor. To use SW1, P1.06 must be configured as an input with an internal pull-up resistor.
The LEDs are active low, which means that writing a logical zero '0' to the output pin will illuminate the LED.
1 SW2 is also connected to P0.19, P0.21,
P0.23, and P0.25. This is done to simplify PCB routing. These GPIOs
should not be used and should be left as input with no pull or be disconnected by
firmware.