Digilent AVR Programmer - Manual (Page 3)

Digilent AVR Programmer Reference Manual Digilent, Inc.
www.digilentinc.com page 3 of 8
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different devices, the programmer needs to
know certain properties of the device being
programmed. This information can be provided
in one of three ways: Digilent part description
files, Atmel part description files, or manual
settings.
Digilent part description files contain the
required device programming information, plus
additional information used to describe the
fuses and lock bits available. Digilent makes
available a part description file for the AVR
devices used on Digilent product boards.
These are installed when the AVR
Programmer is installed. Additional or updated
device files can be downloaded from the
Digilent web site. The Digilent AVR Part
Description File Specification document is also
available for download. It describes the syntax
conventions used in a Digilent part description
file so that you can create part description files.
See
www.digilentinc.com for more information.
Atmel part description files are installed when
the Atmel AVR Studio application is installed.
These files contain the required device
information and some of the additional
information that describes the fuses and lock
bits available in the device.
If no part description file is available for a
device, you can enter the required information
using the AVR Device Manual Settings fields
on the Device Settings tab. The information to
be entered in these fields can be found in the
Memory Programming section of the part data
sheet for the specific AVR device. AVR part
data sheets can be downloaded from Atmel at
www.atmel.com. When manual settings are
being used, the list boxes in the Fuses and
Lock Bits tabs will be empty. The fuses and
lock bits values must be entered as
hexadecimal values in the Value field.
Complete descriptions for the fuses and lock
bits for a device are found in the Memory
Programming section of the device data sheet.
The AVR Device drop-down list box on the
Program tab lists the available device files and
the manual settings option. Manual Settings is
listed first, followed by the available Digilent
part description files, and then the Atmel part
description files.
The part description files are listed by file name
in the drop-down list box. If two files having the
same name appear in the list, the first one
found will be used. Since the Digilent files are
looked for before the Atmel files, a Digilent file
will override an Atmel file having the same
name.
Signature Bytes
Each AVR device contains a device signature.
This is a three-byte sequence that identifies
the specific device. Before any programming
operation, the AVR programmer checks the
signature bytes read from the device with the
signature bytes for the selected device. If the
signatures don’t match no action is performed.
This prevents accidentally damaging a device
by programming it with data for a different part.