Interface MCU
• Flexible baudrate setting up to 1 Mbps.
• Dynamic Hardware Flow Control (HWFC) handling.
• Tri-stated UART lines when no terminal is connected.
Table 1: Relationship of UART connections on nRF52832 and Interface MCU
on page 10 shows an
overview of the UART connections on nRF52832 and the interface MCU.
Default GPIO nRF52832
UART nRF52832
Interface MCU UART
P0.05
RTS
CTS
P0.06
TXD
RXD
P0.07
CTS
RTS
P0.08
RXD
TXD
Table 1: Relationship of UART connections on nRF52832 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.
Important:
The terminal used must send a DTR signal in order to configure the UART Interface
MCU pins.
The P0.05 (RTS) and P0.07 (CTS) can be used freely when HWFC is disabled on the nRF52832.
5.3 Interface MCU firmware (FW)
The on-board interface MCU is factory programmed with an mbed-compliant bootloader. This makes it
possible to update the SEGGER J-Link OB interface firmware.
For more information on entering the bootloader mode, see
IF Boot/Reset button
on page 9.
To update Interface MCU firmware, drag the Interface image (.bin) into the mounted bootloader drive on
the connected computer and power cycle the board. It is also possible to download the latest SEGGER J-
Link software from
SEGGER J-Link Software
and open a debug session in order to automatically update to
the latest J-Link OB firmware version.
The J-Link OB image can be downloaded from
www.nordicsemi.com
.
Important:
When in bootloader mode, do not drag and drop any file except those downloaded
from
www.nordicsemi.com
for use with the Interface MCU. If a wrong file is used, it can overwrite
the bootloader and ruin the Interface MCU firmware without the possibility of recovery.
5.4 MSD
The interface MCU features a mass storage device (MSD). This makes the development kit appear as an
external drive on your computer.
This drive can be used for drag-and-drop programming. 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.
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