Mass storage device

nRF52840 DK Hardware

The interface MCU features a Mass Storage Device (MSD). This makes the Development Kit (DK) appear as an external drive on your computer.

This drive can be used for drag-and-drop programming. However, files cannot be stored on the drive. When a HEX file is copied to the drive, the interface MCU programs the file to the DK.

The following issues might occur during MSD operation.

  • If Windows tries to defragment the MSD, the interface MCU disconnects and becomes unresponsive. To return to normal operation, power cycle the DK.
  • The antivirus software might try to scan the MSD. Some antivirus programs trigger a false positive alert in one of the files and quarantine the unit. If this happens, the interface MCU becomes unresponsive.
  • If the computer is set up to boot from USB, it can try to boot from the DK if it is connected. This can be avoided by unplugging the DK before a computer restart or changing the boot sequence of the computer.

You can disable the MSD of the DK by using the msddisable command in J-Link Commander. To enable, use the msdenable command. These commands take effect after a power cycle of the DK and stay this way until they are changed.