AVR16EB32 datasheet(17/46 Pages) MICROCHIP

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AVR16EB32 Curiosity Nano

On-Board Debugger

User Guide

DS50003605B - 17

before sending the break, which is also in line with expected break character usage: For example,

reset a receiver state-machine after a timeout occurs waiting for returning data to the host.

• The CDC specification allows for debugger-timed breaks of up to 65534 ms in duration to be

requested. For simplicity, the debugger will limit the break duration to a maximum of 11 bit-

durations at its minimum supported baud rate.

• The CDC specification allows for indefinite host-timed breaks. It is the responsibility of the

terminal application/user to release the break state in this case.

Note: Sending break characters is available in debugger firmware version 1.24 and later.

3.5

Mass Storage Device

The on-board debugger includes a simple Mass Storage Device implementation, which is accessible

for read/write operations via the host operating system to which it is connected.

It provides:

• Read access to basic text and HTML files for detailed kit information and support

• Write access for programming Intel® HEX formatted files into the target device’s memory

• Write access for simple text files for utility purposes

3.5.1

Mass Storage Device Implementation

The on-board debugger implements a highly optimized variant of the FAT12 file system with several

limitations, partly due to the nature of FAT12 itself and optimizations made to fulfill its purpose for

its embedded application.

The Curiosity Nano USB device is USB Chapter 9-compliant as a mass storage device but does

not, in any way, fulfill the expectations of a general purpose mass storage device. This behavior is

intentional.

When using the Windows operating system, the on-board debugger enumerates as a Curiosity Nano

USB Device found in the disk drives section of the device manager. The CURIOSITY drive appears in

the file manager and claims the following available drive letter in the system.

The CURIOSITY drive contains approximately one MB of free space and does not reflect the target

device’s Flash size. When programming an Intel HEX file, the binary data are encoded in ASCII with

metadata providing a vast overhead, so 1 MB is a trivially chosen value for disk size.

It is not possible to format the CURIOSITY drive. The filename may appear in the disk directory listing

when programming a file to the target, which is merely the operating system’s view of the directory

that, in reality, has not been updated. It is not possible to read out the file contents. Removing and

replugging the board will return the file system to its original state, but the target will still contain

the previously programmed application.

Copy a text file starting with “CMD:ERASE” onto the disk to erase the target device.

By default, the CURIOSITY drive contains several read-only files for generating icons as well as

reporting status and linking to further information:

• AUTORUN.ICO – icon file for the Microchip logo

• AUTORUN.INF – system file required for Windows Explorer to show the icon file

• KIT-INFO.HTM – redirect to the development board website

• KIT-INFO.TXT – a text file containing details about the board’s debugger firmware version,

board name, USB serial number, device, and drag-and-drop support

• STATUS.TXT – a text file containing the programming status of the board

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