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
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).