nRF52 Preview DK v1.1.x

IF Boot/Reset button

The nRF52 PDK is equipped with a boot/reset button (SW5).

This button is connected to the Interface MCU on the DK and has two functions: During normal operation the button will function as a reset button for the nRF52832 device. For this to work, pin reset on P0.21 needs to be enabled for the nRF52832 device. The button is also used to enter the bootloader mode of the Interface MCU. To enter bootloader mode, keep the reset button pressed while powering up the DK until LED (LD5) starts to blink. You can power up the DK either by disconnecting and reconnecting the USB cable, or toggle the power switch (SW6).
Important: Pin reset can be enabled by defining the CONFIG_GPIO_AS_PINRESET variable in the project settings. This can be done by defining the preprocessor symbol in Keil, go to: Project > Options for Target > C/C++ > Preprocessor Symbols > Define. Here you can add the CONFIG_GPIO_AS_PINRESET variable after NRF52.

This functionality can be removed by doing a nRFjprog --recover.