Texas Instruments LP-MSPM0C1104 User Manual page 5

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Isolation Jumper Block
The isolation jumper block at jumper J101 allows the user to connect or disconnect signals that cross from the
XDS110 domain into the MSPM0C1104 target domain. This includes XDS110 SWD signals, application UART
signals, and 3.3V and 5 V power.
Jumper
5 V 5-V VBUS from USB.
3V3 3.3-V rail, derived from VBUS in the XDS110-ET domain.
Backchannel UART: The target MSPM0L1306 receives data through this signal. The arrows indicate the direction of the
RXD<<
signal.
Backchannel UART: The target MSPM0L1306 sends data through this signal. The arrows indicate the direction of the
TXD>>
signal.
NRST RST signal.
SWDIO Serial wire debug: SWDIO data signal.
SWCLK Serial wire debug: SWDCLK clock signal.
During normal prototyping all shunts are populated. However, there are some scenarios where a user needs to
open these connections:
• To remove any and all influence from the XDS110 debug probe for high accuracy target power
measurements.
• To control 3.3V and 5 V power flow between the XDS110 and target domains.
• To expose the target MCU pins for other use than onboard debugging and application UART communication.
• To expose the programming and UART interface of the XDS110 so that the XDS110 can be used for devices
other than the onboard MCU.
Application (Backchannel) UART
The backchannel UART allows communication with the USB host that is not part of the target application's
main functionality. This is very useful during development, and also provides a communication channel to the
PC host side. This can be used to create graphical user interfaces (GUIs) and other programs on the PC that
communicate with the LaunchPad development kit.
Figure 2-3 shows the pathway of the backchannel UART. The backchannel UART is connected to UART0 (PA8,
PA9) deepening on the jumper settings on headers J16 and J17.
On the host side, a virtual COM port for the application backchannel UART is generated when the LaunchPad
development kit enumerates on the host. You can use any PC application that interfaces with COM ports,
including terminal applications like Hyperterminal or Docklight, to open this port and communicate with the target
application. You need to identify the COM port for the backchannel. On Windows PCs, Device Manager can
assist.
Figure 2-3. Application Backchannel UART in Device Manager
The backchannel UART is the XDS110 Class Application/User UART port. In this case,
COM14, but this port can vary from one host PC to the next. After identifying the correct COM port, configure
the port in the host application according to documentation. The user can then open the port and begin
communication from the host.
On the target MSPM0C1104 side, the backchannel is connected to the UART0 module. The XDS110 has a
configurable baud rate; therefore, the PC application configuring the baud rate to be the same as what is
configured on the UART0 is important.
SLAU908 – OCTOBER 2023
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Figure 2-3 shows
LP-MSPM0C1104 Evaluation Module 5