avrdude/avrdude.1

.\"
.\" avrdude - A Downloader/Uploader for AVR device programmers
.\" Copyright (C) 2001, 2002, 2003, 2005, 2006  Joerg Wunsch
.\"
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.\" it under the terms of the GNU General Public License as published by
.\" the Free Software Foundation; either version 2 of the License, or
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.\" but WITHOUT ANY WARRANTY; without even the implied warranty of
.\" MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
.\" GNU General Public License for more details.
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.\" along with this program; if not, write to the Free Software
.\" Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
.\"
.\"
.\" $Id$
.\"
.Dd DATE October 26, 2006
.Os
.Dt AVRDUDE 1
.Sh NAME
.Nm avrdude
.Nd driver program for ``simple'' Atmel AVR MCU programmer
.Sh SYNOPSIS
.Nm
.Fl p Ar partno
.Op Fl b Ar baudrate
.Op Fl B Ar bitclock
.Op Fl c Ar programmer-id
.Op Fl C Ar config-file
.Op Fl D
.Op Fl e
.Oo Fl E Ar exitspec Ns
.Op \&, Ns Ar exitspec
.Oc
.Op Fl F
.Op Fl i Ar delay
.Op Fl n
.Op Fl O
.Op Fl P Ar port
.Op Fl q
.Op Fl s
.Op Fl t
.Op Fl u
.Op Fl U Ar memtype:op:filename:filefmt
.Op Fl v
.Op Fl V
.Op Fl y
.Op Fl Y
.Sh DESCRIPTION
.Nm Avrdude
is a program for downloading code and data to Atmel AVR
microcontrollers.
.Nm Avrdude
supports Atmel's STK500 programmer,
Atmel's AVRISP and AVRISP mkII devices,
Atmel's JTAG ICE (both mkI and mkII, the latter also in ISP mode),
programmers complying to AppNote AVR910 and AVR109 (including the Butterfly),
as well as a simple hard-wired
programmer connected directly to a
.Xr ppi 4
or
.Xr parport 4
parallel port, or to a standard serial port.
In the simplest case, the hardware consists just of a
cable connecting the respective AVR signal lines to the parallel port.
.Pp
The MCU is programmed in
.Em serial programming mode ,
so, for the
.Xr ppi 4
based programmer, the MCU signals
.Ql /RESET ,
.Ql SCK ,
.Ql MISO
and
.Ql MOSI
need to be connected to the parallel port.  Optionally, some otherwise
unused output pins of the parallel port can be used to supply power
for the MCU part, so it is also possible to construct a passive
stand-alone programming device.  Some status LEDs indicating the
current operating state of the programmer can be connected, and a
signal is available to control a buffer/driver IC 74LS367 (or
74HCT367).  The latter can be useful to decouple the parallel port
from the MCU when in-system programming is used.
.Pp
A number of equally simple bit-bang programming adapters that connect
to a serial port are supported as well, among them the popular
Ponyprog serial adapter, and the DASA and DASA3 adapters that used to
be supported by uisp(1).
Note that these adapters are meant to be attached to a physical serial
port.
Connecting to a serial port emulated on top of USB is likely to not
work at all, or to work abysmally slow.
.Pp
Atmel's STK500 programmer is also supported and connects to a serial
port.
Both, firmware versions 1.x and 2.x can be handled, but require a
different programmer type specification (by now).
Using firmware version 2, high-voltage programming is also supported,
both parallel and serial
(programmer types stk500pp and stk500hvsp).
.Pp
The simple serial programmer described in Atmel's application note
AVR910, and the bootloader described in Atmel's application note
AVR109 (which is also used by the AVR Butterfly evaluation board), are
supported on a serial port.
.Pp
Atmel's JTAG ICE (both mkI and mkII) is supported as well to up- or download memory
areas from/to an AVR target (no support for on-chip debugging).
For the JTAG ICE mkII, JTAG, debugWire and ISP mode are supported.
See below for the limitations of debugWire.
.Pp
The AVR Dragon is supported in all modes (ISP, JTAG, HVSP, PP, debugWire).
When used in JTAG and debugWire mode, the AVR Dragon behaves similar to a
JTAG ICE mkII, so all device-specific comments for that device
will apply as well.
When used in ISP mode, the AVR Dragon behaves similar to an
AVRISP mkII (or JTAG ICE mkII in ISP mode), so all device-specific
comments will apply there.
In particular, the Dragon starts out with a rather fast ISP clock
frequency, so the
.Fl B Ar bitclock
option might be required to achieve a stable ISP communication.
.Pp
The USBasp ISP adapter is also supported, provided
.Nm avrdude
has been compiled with libusb support.
It features a simple firwmare-only USB implementation, running on
an ATmega8 (or ATmega88).
.Pp
Input files can be provided, and output files can be written in
different file formats, such as raw binary files containing the data
to download to the chip, Intel hex format, or Motorola S-record
format.  There are a number of tools available to produce those files,
like
.Xr asl 1
as a standalone assembler, or
.Xr avr-objcopy 1
for the final stage of the GNU toolchain for the AVR microcontroller.
.Pp
.Nm Avrdude
can program the EEPROM and flash ROM memory cells of supported AVR
parts.  Where supported by the serial instruction set, fuse bits and
lock bits can be programmed as well.  These are implemented within
.Nm
as separate memory types and can be programmed using data from a file
(see the
.Fl m
option) or from terminal mode (see the
.Ar dump
and
.Ar write
commands).  It is also possible to read the chip (provided it has not
been code-protected previously, of course) and store the data in a
file.  Finally, a ``terminal'' mode is available that allows one to
interactively communicate with the MCU, and to display or program
individual memory cells.
On the STK500 programmer, several operational parameters (target supply
voltage, target Aref voltage, master clock) can be examined and changed
from within terminal mode as well.
.Ss Options
In order to control all the different operation modi, a number of options
need to be specified to
.Nm avrdude .
.Bl -tag -offset indent -width indent
.It Fl p Ar partno
This is the only option that is mandatory for every invocation of
.Nm avrdude .
It specifies the type of the MCU connected to the programmer.  These are read from the config file.  If
.Nm avrdude
does not know about a part that you have, simply add it to the config
file (be sure and submit a patch back to the author so that it can be
incorporated for the next version).  See the sample config file for
the format.  Currently, the following MCU types are understood:
.Pp
.TS
ll.
\fBOption tag\fP	\fBOfficial part name\fP
c128	AT90CAN128
pwm2	AT90PWM2
pwm3	AT90PWM3
1200	AT90S1200
2313	AT90S2313
2333	AT90S2333
2343	AT90S2343 (*)
4414	AT90S4414
4433	AT90S4433
4434	AT90S4434
8515	AT90S8515
8535	AT90S8535
m103	ATmega103
m128	ATmega128
m1280	ATmega1280
m1281	ATmega1281
m16	ATmega16
m161	ATmega161
m162	ATmega162
m163	ATmega163
m164	ATmega164
m169	ATmega169
m2560	ATmega2560 (**)
m2561	ATmega2561 (**)
m32	ATmega32
m324	ATmega324
m329	ATmega329
m3290	ATmega3290
m48	ATmega48
m64	ATmega64
m640	ATmega640
m644	ATmega644
m649	ATmega649
m6490	ATmega6490
m8	ATmega8
m8515	ATmega8515
m8535	ATmega8535
m88	ATmega88
t12	ATtiny12
t13	ATtiny13
t15	ATtiny15
t2313	ATtiny2313
t25	ATtiny25
t26	ATtiny26
t45	ATtiny45
t85	ATtiny85
.TE
.Bl -tag -width "(**) "
.It "(*)"
The AT90S2323 and ATtiny22 use the same algorithm.
.It "(**)"
Flash addressing above 128 KB is not supported by all
programming hardware.  Known to work are jtag2, stk500v2,
and bit-bang programmers.
.El
.It Fl b Ar baudrate
Override the RS-232 connection baud rate specified in the respective
programmer's entry of the configuration file.
.It Fl B Ar bitclock
Specify the bit clock period for the JTAG interface or the ISP clock (JTAG ICE only).
The value is a floating-point number in microseconds.
The default value of the JTAG ICE results in about 1 microsecond bit
clock period, suitable for target MCUs running at 4 MHz clock and
above.
Unlike certain parameters in the STK500, the JTAG ICE resets all its
parameters to default values when the programming software signs
off from the ICE, so for MCUs running at lower clock speeds, this
parameter must be specified on the command-line.
.It Fl c Ar programmer-id
Use the pin configuration specified by the argument.  Pin
configurations are read from the config file (see the
.Fl C
option).  New pin configurations can be easily added or modified
through the use of a config file to make
.Nm avrdude
work with different programmers as long as the programmer supports the
Atmel AVR serial program method.  You can use the 'default_programmer'
keyword in your
.Pa ${HOME}/.avrduderc
file to assign a default programmer to keep from having to specify
this option on every invocation.
.It Fl C Ar config-file
Use the specified config file to load configuration data.  This file
contains all programmer and part definitions that
.Nm avrdude
knows about.  If you have a programmer or part that
.Nm avrdude
does not know about, you can add it to the config file (be sure and
submit a patch back to the author so that it can be incorporated for
the next version).  See the config file, located at
.Pa ${PREFIX}/etc/avrdude.conf ,
which contains a description of the format.
.It Fl D
Disable auto erase for flash.  When the
.Fl U
option with flash memory is specified,
.Nm
will perform a chip erase before starting any of the programming
operations, since it generally is a mistake to program the flash
without performing an erase first.  This option disables that.
.It Fl e
Causes a chip erase to be executed.  This will reset the contents of the
flash ROM and EEPROM to the value
.Ql 0xff ,
and is basically a prerequisite command before the flash ROM can be
reprogrammed again.  The only exception would be if the new
contents would exclusively cause bits to be programmed from the value
.Ql 1
to
.Ql 0 .
Note that in order to reprogram EERPOM cells, no explicit prior chip
erase is required since the MCU provides an auto-erase cycle in that
case before programming the cell.
.It Xo Fl E Ar exitspec Ns
.Op \&, Ns Ar exitspec
.Xc
By default,
.Nm
leaves the parallel port in the same state at exit as it has been
found at startup.  This option modifies the state of the
.Ql /RESET
and
.Ql Vcc
lines the parallel port is left at, according to the
.Ar exitspec
arguments provided, as follows:
.Bl -tag -width noreset
.It Ar reset
The
.Ql /RESET
signal will be left activated at program exit, that is it will be held
.Em low ,
in order to keep the MCU in reset state afterwards.  Note in particular
that the programming algorithm for the AT90S1200 device mandates that
the
.Ql /RESET
signal is active
.Em before
powering up the MCU, so in case an external power supply is used for this
MCU type, a previous invocation of
.Nm
with this option specified is one of the possible ways to guarantee this
condition.
.It Ar noreset
The
.Ql /RESET
line will be deactivated at program exit, thus allowing the MCU target
program to run while the programming hardware remains connected.
.It Ar vcc
This option will leave those parallel port pins active
.Pq \&i. \&e. Em high
that can be used to supply
.Ql Vcc
power to the MCU.
.It Ar novcc
This option will pull the
.Ql Vcc
pins of the parallel port down at program exit.
.El
.Pp
Multiple
.Ar exitspec
arguments can be separated with commas.
.It Fl F
Normally,
.Nm
tries to verify that the device signature read from the part is
reasonable before continuing.  Since it can happen from time to time
that a device has a broken (erased or overwritten) device signature
but is otherwise operating normally, this options is provided to
override the check.
.It Fl i Ar delay
For bitbang-type programmers, delay for approximately
.Ar delay
microseconds between each bit state change.
If the host system is very fast, or the target runs off a slow clock
(like a 32 kHz crystal, or the 128 kHz internal RC oscillator), this
can become necessary to satisfy the requirement that the ISP clock
frequency must not be higher than 1/4 of the CPU clock frequency.
This is implemented as a spin-loop delay to allow even for very
short delays.
On Unix-style operating systems, the spin loop is initially calibrated
against a system timer, so the number of microseconds might be rather
realistic, assuming a constant system load while
.Nm
is running.
On Win32 operating systems, a preconfigured number of cycles per
microsecond is assumed that might be off a bit for very fast or very
slow machines.
.It Fl n
No-write - disables actually writing data to the MCU (useful for debugging
.Nm avrdude
).
.It Fl O
Perform a RC oscillator run-time calibration according to Atmel
application note AVR053.
This is only supported on the STK500v2, AVRISP mkII, and JTAG ICE mkII
hardware.
Note that the result will be stored in the EEPROM cell at address 0.
.It Fl P Ar port
Use
.Ar port
to identify the device to which the programmer is attached.  By
default the
.Pa /dev/ppi0
port is used, but if the programmer type normally connects to the
serial port, the
.Pa /dev/cuaa0
port is the default.  If you need to use a different parallel or
serial port, use this option to specify the alternate port name.
.Pp
For the JTAG ICE mkII, if
.Nm
has been configured with libusb support,
.Ar port
can alternatively be specified as
.Pa usb Ns Op \&: Ns Ar serialno .
This will cause
.Nm
to search a JTAG ICE mkII on USB.
If
.Ar serialno
is also specified, it will be matched against the serial number read
from any JTAG ICE mkII found on USB.
The match is done after stripping any existing colons from the given
serial number, and right-to-left, so only the least significant bytes
from the serial number need to be given.
.Pp
As the AVRISP mkII device can only be talked to over USB, the very
same method of specifying the port is required there.
.Pp
For programmers that attach to a serial port using some kind of
higher level protocol (as opposed to bit-bang style programmers),
.Ar port
can be specified as
.Pa net Ns \&: Ns Ar host Ns \&: Ns Ar port .
In this case, instead of trying to open a local device, a TCP
network connection to (TCP)
.Ar port
on
.Ar host
is established.
The remote endpoint is assumed to be a terminal or console server
that connects the network stream to a local serial port where the
actual programmer has been attached to.
The port is assumed to be properly configured, for example using a
transparent 8-bit data connection without parity at 115200 Baud
for a STK500.
.Em This feature is currently not implemented for Win32 systems.
.It Fl q
Disable (or quell) output of the progress bar while reading or writing
to the device.  Specify it a second time for even quieter operation.
.It Fl s
Disable safemode prompting.  When safemode discovers that one or more
fuse bits have unintentionally changed, it will prompt for
confirmation regarding whether or not it should attempt to recover the
fuse bit(s).  Specifying this flag disables the prompt and assumes
that the fuse bit(s) should be recovered without asking for
confirmation first.
.It Fl t
Tells
.Nm
to enter the interactive ``terminal'' mode instead of up- or downloading
files.  See below for a detailed description of the terminal mode.
.It Fl u
Disable the safemode fuse bit checks.  Safemode is enabled by default
and is intended to prevent unintentional fuse bit changes.  When
enabled, safemode will issue a warning if the any fuse bits are found
to be different at program exit than they were when
.Nm
was invoked.  Safemode won't alter fuse bits itself, but rather will
prompt for instructions, unless the terminal is non-interactive, in
which case safemode is disabled.  See the
.Fl s
option to disable safemode prompting.
.It Xo Fl U Ar memtype Ns
.Ar \&: Ns Ar op Ns
.Ar \&: Ns Ar filename Ns
.Op \&: Ns Ar format
.Xc
Perform a memory operation as indicated.  The
.Ar memtype
field specifies the memory type to operate on.
The available memory types are device-dependent, the actual
configuration can be viewed with the
.Cm part
command in terminal mode.
Typically, a device's memory configuration at least contains
the memory types
.Ar flash
and
.Ar eeprom .
All memory types currently known are:
.Bl -tag -width "calibration" -compact
.It calibration
One or more bytes of RC oscillator calibration data.
.It eeprom
The EEPROM of the device.
.It efuse
The extended fuse byte.
.It flash
The flash ROM of the device.
.It fuse
The fuse byte in devices that have only a single fuse byte.
.It hfuse
The high fuse byte.
.It lfuse
The low fuse byte.
.It lock
The lock byte.
.It signature
The three device signature bytes (device ID).
.El
.Pp
The
.Ar op
field specifies what operation to perform:
.Bl -tag -width noreset
.It Ar r
read device memory and write to the specified file
.It Ar w
read data from the specified file and write to the device memory
.It Ar v
read data from both the device and the specified file and perform a verify
.El
.Pp
The
.Ar filename
field indicates the name of the file to read or write.
The
.Ar format
field is optional and contains the format of the file to read or
write.
.Ar Format
can be one of:
.Bl -tag -width sss
.It Ar i
Intel Hex
.It Ar s
Motorola S-record
.It Ar r
raw binary; little-endian byte order, in the case of the flash ROM data
.It Ar m
immediate; actual byte values specified on the command line, separated
by commas or spaces.  This is good for programming fuse bytes without
having to create a single-byte file or enter terminal mode.
.It Ar a
auto detect; valid for input only, and only if the input is not
provided at
.Em stdin .
.It Ar d
decimal; this and the following formats are only valid on output.
They generate one line of output for the respective memory section,
forming a comma-separated list of the values.
This can be particularly useful for subsequent processing, like for
fuse bit settings.
.It Ar h
hexadecimal; each value will get the string
.Em 0x
prepended.
.It Ar o
octal; each value will get a
.Em 0
prepended unless it is less than 8 in which case it gets no prefix.
.It Ar b
binary; each value will get the string
.Em 0b
prepended.
.El
.Pp
The default is to use auto detection for input files, and raw binary
format for output files.
Note that if
.Ar filename
contains a colon, the
.Ar format
field is no longer optional since the filename part following the colon
would otherwise be misinterpreted as
.Ar format .
.Pp
As an abbreviation, the form
.Fl U Ar filename
is equivalent to specifying
.Fl U Em flash:w: Ns Ar filename Ns :a .
This will only work if
.Ar filename
does not have a colon in it.
.It Fl v
Enable verbose output.
.It Fl V
Disable automatic verify check when uploading data.
.It Fl y
Tells
.Nm
to use the last four bytes of the connected parts' EEPROM memory to
track the number of times the device has been erased.  When this
option is used and the
.Fl e
flag is specified to generate a chip erase, the previous counter will
be saved before the chip erase, it is then incremented, and written
back after the erase cycle completes.  Presumably, the device would
only be erased just before being programmed, and thus, this can be
utilized to give an indication of how many erase-rewrite cycles the
part has undergone.  Since the FLASH memory can only endure a finite
number of erase-rewrite cycles, one can use this option to track when
a part is nearing the limit.  The typical limit for Atmel AVR FLASH is
1000 cycles.  Of course, if the application needs the last four bytes
of EEPROM memory, this option should not be used.
.It Fl Y Ar cycles
Instructs
.Nm
to initialize the erase-rewrite cycle counter residing at the last four
bytes of EEPROM memory to the specified value.  If the application
needs the last four bytes of EEPROM memory, this option should not be
used.
.El
.Ss Terminal mode
In this mode,
.Nm
only initializes communication with the MCU, and then awaits user
commands on standard input.  Commands and parameters may be
abbreviated to the shortest unambiguous form.  Terminal mode provides
a command history using
.Xr readline 3 ,
so previously entered command lines can be recalled and edited.  The
following commands are currently implemented:
.Bl -tag -offset indent -width indent
.It Ar dump memtype addr nbytes
Read
.Ar nbytes
bytes from the specified memory area, and display them in the usual
hexadecimal and ASCII form.
.It Ar dump
Continue dumping the memory contents for another
.Ar nbytes
where the previous
.Ar dump
command left off.
.It Ar write memtype addr byte1 ... byteN
Manually program the respective memory cells, starting at address
.Ar addr ,
using the values
.Ar byte1
through
.Ar byteN .
This feature is not implemented for bank-addressed memories such as
the flash memory of ATMega devices.
.It Ar erase
Perform a chip erase.
.It Ar send b1 b2 b3 b4
Send raw instruction codes to the AVR device.  If you need access to a
feature of an AVR part that is not directly supported by
.Nm ,
this command allows you to use it, even though
.Nm
does not implement the command.
.It Ar sig
Display the device signature bytes.
.It Ar part
Display the current part settings and parameters.  Includes chip
specific information including all memory types supported by the
device, read/write timing, etc.
.It Ar vtarg voltage
Set the target's supply voltage to
.Ar voltage
Volts.
.Em Only supported on the STK500 programmer.
.It Ar varef voltage
Set the adjustable voltage source to
.Ar voltage
Volts.
This voltage is normally used to drive the target's
.Em Aref
input on the STK500.
.Em Only supported on the STK500 programmer.
.It Ar fosc freq Ns Op M Ns \&| Ns k
Set the master oscillator to
.Ar freq
Hz.
An optional trailing letter
.Ar \&M
multiplies by 1E6, a trailing letter
.Ar \&k
by 1E3.
.Em Only supported on the STK500 programmer.
.It Ar fosc off
Turn the master oscillator off.
.Em Only supported on the STK500 programmer.
.It Ar sck period
.Em STK500 programmer only:
Set the SCK clock period to
.Ar period
microseconds.
.Pp
.Em JTAG ICE only:
Set the JTAG ICE bit clock period to
.Ar period
microseconds.
Note that unlike STK500 settings, this setting will be reverted to
its default value (approximately 1 microsecond) when the programming
software signs off from the JTAG ICE.
This parameter can also be used on the JTAG ICE mkII to specify the
ISP clock period when operating the ICE in ISP mode.
.It Ar parms
.Em STK500 programmer only:
Display the current voltage and master oscillator parameters.
.Pp
.Em JTAG ICE only:
Display the current target supply voltage and JTAG bit clock rate/period.
.It Ar \&?
.It Ar help
Give a short on-line summary of the available commands.
.It Ar quit
Leave terminal mode and thus
.Nm avrdude .
.El
.Ss Default Parallel port pin connections
(these can be changed, see the
.Fl c
option)
.TS
ll.
\fBPin number\fP	\fBFunction\fP
2-5	Vcc (optional power supply to MCU)
7	/RESET (to MCU)
8	SCK (to MCU)
9	MOSI (to MCU)
10	MISO (from MCU)
18-25	GND
.TE
.Ss debugWire limitations
The debugWire protocol is Atmel's proprietary one-wire (plus ground)
protocol to allow an in-circuit emulation of the smaller AVR devices,
using the
.Ql /RESET
line.
DebugWire mode is initiated by activating the
.Ql DWEN
fuse, and then power-cycling the target.
While this mode is mainly intented for debugging/emulation, it
also offers limited programming capabilities.
Effectively, the only memory area that can be read or programmed
in this mode is the flash ROM.
It is also possible to read out the signature.
All other memory areas cannot be accessed.
There is no
.Em chip erase
functionality in debugWire mode; instead, while reprogramming the
flash ROM, each flash ROM page is erased right before updating it.
This is done transparently by the JTAG ICE mkII (or AVR Dragon).
The only way back from debugWire mode is to initiate a special
sequence of commands to the JTAG ICE mkII (or AVR Dragon), so the
debugWire mode will be temporarily disabled, and the target can
be accessed using normal ISP programming.
This sequence is automatically initiated by using the JTAG ICE mkII
or AVR Dragon in ISP mode, when they detect that ISP mode cannot be
entered.
.Sh FILES
.Bl -tag -offset indent -width /dev/ppi0XXX
.It Pa /dev/ppi0
default device to be used for communication with the programming
hardware
.It Pa ${PREFIX}/etc/avrdude.conf
programmer and parts configuration file
.It Pa ${HOME}/.avrduderc
programmer and parts configuration file (per-user overrides)
.It Pa ~/.inputrc
Initialization file for the
.Xr readline 3
library
.It Pa ${PREFIX}/share/doc/avrdude/avrdude.pdf
Schematic of programming hardware
.El
.\" .Sh EXAMPLES
.Sh DIAGNOSTICS
.Bd -literal
avrdude: jtagmkII_setparm(): bad response to set parameter command: RSP_FAILED
avrdude: jtagmkII_getsync(): ISP activation failed, trying debugWire
avrdude: Target prepared for ISP, signed off.
avrdude: Please restart avrdude without power-cycling the target.
.Ed
.Pp
If the target AVR has been set up for debugWire mode (i. e. the
.Em DWEN
fuse is programmed), normal ISP connection attempts will fail as
the
.Em /RESET
pin is not available.
When using the JTAG ICE mkII in ISP mode, the message shown indicates
that
.Nm
has guessed this condition, and tried to initiate a debugWire reset
to the target.
When successful, this will leave the target AVR in a state where it
can respond to normal ISP communication again (until the next power
cycle).
Typically, the same command is going to be retried again immediately
afterwards, and will then succeed connecting to the target using
normal ISP communication.
.Sh SEE ALSO
.Xr avr-objcopy 1 ,
.Xr ppi 4 ,
.Xr readline 3
.Pp
The AVR microcontroller product description can be found at
.Pp
.Dl "http://www.atmel.com/products/AVR/"
.\" .Sh HISTORY
.Sh AUTHORS
.Nm Avrdude
was written by Brian S. Dean <bsd@bsdhome.com>.
.Pp
This man page by
.ie t J\(:org Wunsch.
.el Joerg Wunsch.
.Sh BUGS
Please report bugs via
.Dl "http://savannah.nongnu.org/bugs/?group=avrdude" .
.Pp
The JTAG ICE programmers currently cannot write to the flash ROM
one byte at a time.
For that reason, updating the flash ROM from terminal mode does not
work.
.Pp
Page-mode programming the EEPROM through JTAG (i.e. through an
.Fl U
option) requires a prior chip erase.
This is an inherent feature of the way JTAG EEPROM programming works.
This also applies to the STK500 in parallel programming mode.
.Pp
The USBasp driver does not offer any option to distinguish multiple
devices connected simultaneously, so effectively only a single device
is supported.