Interface MCU
The following table shows an overview of the UART connections on the nRF52832
and the interface
MCU.
GPIO nRF52832
nRF52832 UART
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.
Note:
The terminal software used must send a
signal to configure the
UART interface MCU pins.
P0.05
) and
P0.07
) can be used freely when HWFC is disabled
on the SoC.
Note:
The Mbed OB interface does not support HWFC through the virtual COM port.
3.2.1 Dynamic HWFC handling
When the interface MCU receives a
signal from a terminal, it performs automatic
detection.
Automatic HWFC detection is done by driving
P0.07
) from the interface MCU and evaluating the state
of
P0.05
) when the first data is sent or received. If the state of
P0.05
(RTS) is high, HWFC is assumed
not to be used. If HWFC is not detected, both CTS and RTS can be used freely by the nRF application.
After a power-on reset of the interface MCU, all
lines are tri-stated when no terminal is connected
to the virtual COM port. Due to the dynamic HWFC handling, if HWFC has been used and detected,
P0.07
(CTS) is driven by the interface MCU until a power-on reset has been performed or until a new DTR signal
is received and the detection is redone.
To ensure that the UART lines are not affected by the interface MCU, the solder bridges for these signals
can be cut and later resoldered if needed. This might be necessary if UART without HWFC is needed while
P0.05
(RTS) and
P0.07
(CTS) are used for other purposes.
3.3 Interface MCU firmware
The onboard interface MCU is factory programmed with an Mbed-compliant bootloader. This feature
makes it possible to swap interface firmware between the factory preloaded SEGGER J-Link OB and the
Mbed interface firmware.
See
on page 6 for instructions on how to enter the bootloader mode.
To swap interface MCU firmware, drag the Interface image (.bin) into the mounted bootloader drive on
the connected computer and power cycle the DK.
Both the Mbed interface firmware and the J-Link OB image can be downloaded from
.
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