nRF21540 DK IF Boot/Reset button

The nRF21540 DK is equipped with an IF Boot/Reset button (SW5).

This button is connected to the interface MCU on the Development Kit (DK) and has two functions:

Resetting the nRF52840 System on Chip (SoC)
Entering bootloader mode of the interface MCU

During normal operation, the button functions as a reset button for the nRF52840 SoC. For this to work, pin reset on P0.18 needs to be enabled in the SoC.

The button is also used to enter the bootloader mode of the interface MCU. To enter the bootloader mode, keep the reset button pressed while powering up the DK until LED5 starts to blink. You can power up the DK either by disconnecting and reconnecting the Universal Serial Bus (USB) cable or by toggling the power switch (SW8).

Note: Pin reset is enabled by setting the CONFIG_GPIO_AS_PINRESET variable to y. See Configuring your application for instructions.