Interface MCU
The virtual COM port has the following features:
•
Flexible baud rate setting up to 1 Mbps.
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• Dynamic Hardware Flow Control (HWFC) handling.
• Tri-stated UART lines when no terminal is connected.
The table below shows an overview of the UART connections on the nRF52833 SoC and the interface MCU.
GPIO nRF52833 nRF52833 UART
P0.05 RTS
P0.06 TXD
P0.07 CTS
P0.08 RXD
Table 1: Relationship of UART connections on nRF52833 and interface MCU
The UART signals are routed directly to the interface MCU. The UART pins connected to the interface MCU
are tri-stated when no terminal is connected to the virtual COM port on the computer.
Note: The terminal software used must send a Data Terminal Ready (DTR) signal to configure the
UART interface MCU pins.
The P0.05 (Request to Send (RTS)) and P0.07 (Clear to Send (CTS)) can be used freely when HWFC is
disabled on the SoC.
7.3 MSD
The interface MCU features an MSD. This makes the 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 this drive. By
copying a HEX file to the drive, the interface MCU will program the file to the device.
Note:
• Windows might try to defragment the MSD part of the interface MCU. If this happens, the
interface MCU will disconnect and be unresponsive. To return to normal operation, the DK must
be power cycled.
• Your antivirus software might try to scan the MSD part of the interface MCU. Some antivirus
programs trigger a false positive alert in one of the files and quarantine the unit. If this happens,
the interface MCU will become unresponsive.
• If the computer is set up to boot from USB, it can try to boot from the DK if the DK is connected
during boot. This can be avoided by unplugging the DK before a computer restart, or changing
the boot sequence of the computer.
You can also disable the MSD of the kit 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 changed again.
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Baud rate 921 600 is not supported through the virtual COM port.
4452_198 v1.0.1
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