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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 GUIs and other programs on the PC that communicate with

the LaunchPad.

The pathway of the backchannel UART is shown in Figure 7. The backchannel UART eUSCI_A0 is

independent of the UART on the 40-pin BoosterPack connector eUSCI_A2.

On the host side, a virtual COM port for the application backchannel UART is generated when the

LaunchPad 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 7. Application Backchannel UART in Device Manager

The backchannel UART is the XDS110 Class Application/User UART port. In this case, Figure 7 shows

COM156, but this port can vary from one host PC to the next. After you identify the correct COM port,

configure it in your host application according to its documentation. You can then open the port and begin

communication to it from the host.

The XDS110-ET has a configurable baud rate; therefore, it is important that the PC application configures

the baud rate to be the same as what is configured on the eUSCI_A0 backchannel UART.

SLAU597–March 2015 MSP

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EXP432P401R LaunchPad™ Evaluation Kit

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