3.1.1 Overview

The on-board debugger implements a composite USB device that includes a standard Communications Device Class (CDC) interface, which appears on the host as a virtual serial port. The CDC can be used to stream arbitrary data in both directions between the host computer and the target: All characters sent through the virtual serial port on the host computer will be transmitted as UART on the debugger’s CDC TX pin, and UART characters captured on the debugger’s CDC RX pin will be returned to the host computer through the virtual serial port.

Figure 3-1. CDC Connection
Info: As shown in Figure 3-1, the debugger’s CDC TX pin is connected to a UART RX pin on the target for receiving characters from the host computer. Similarly, the debugger’s CDC RX pin is connected to a UART TX pin on the target for transmitting characters to the host computer.