The interface MCU on the nRF21540 DK runs SEGGER J-Link OB
interface firmware and is used to program and debug the firmware of the nRF52840 System on Chip (SoC).
Figure 1. Interface MCU
IF Boot/Reset button
The nRF21540 DK is equipped with an IF Boot/Reset button (SW5).
Virtual COM port
The onboard interface MCU features a UART interface through a virtual COM port.
MSD
The interface MCU features aMSD. This makes the DK appear as an external drive on your computer.