Datasheet

Other Pins

A tactile switch is provided for use in your projects,

which is connected to P0.29 and is accessible in code

as D4.

Holding this button down coming out of a board reset

will also force the device to enter and remain in USB

bootloader mode, which can be useful if you lock your

board up with bad application code!

RST - this is the Reset pin, tie to ground to manually

reset the nRF52840, as well as launch the bootloader

manually

SWCLK & SWDIO - These are the debug-interface pins,

used if you want to reprogram the chip directly or attach

a debugger.