Remember:  Keep the debugger’s firmware up-to-date. Firmware upgrades are done automatically when

using Atmel Studio/Microchip MPLAB® X IDE.

3.1.2

Virtual Serial Port (CDC)

The virtual serial port (CDC) is a general purpose serial bridge between a host PC and a target device.

3.1.2.1

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

Target MCU

UART TX

UART RX

Debugger

USB

CDC RX

CDC TX

PC

Terminal

Software

Target

Receive

Target

Send

Terminal

Receive

Terminal

Send

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.

3.1.2.2

Operating System Support

On Windows machines, the CDC will enumerate as Curiosity Virtual COM Port and appear in the Ports section of the

Windows Device Manager. The COM port number can also be found there.

Info:  On older Windows systems, a USB driver is required for CDC. This driver is included in installations

of Atmel Studio/Microchip MPLAB® X IDE.

On Linux machines, the CDC will enumerate and appear as /dev/ttyACM#.

Info:  tty* devices belong to the “dialout” group in Linux, so it may be necessary to become a member of

that group to have permissions to access the CDC.

On MAC machines, the CDC will enumerate and appear as /dev/tty.usbmodem#. Depending on which terminal

program is used, it will appear in the available list of modems as usbmodem#.

ATtiny1627

Curiosity Nano

© 2020 Microchip Technology Inc.

User Guide

DS40002199A-page 8