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AVRDUDE command line reference

AVRDUDE is a command line tool, used as follows:

avrdude -p partno options

Command line options are used to control AVRDUDE’s behaviour. The following options are recognized:

-p partno

This is the only mandatory option and it tells AVRDUDE what type of part (MCU) that is connected to the programmer. The partno parameter is the part’s id listed in the configuration file. Specify -p ? to list all parts in the configuration file. If a part is unknown to AVRDUDE, it means that there is no config file entry for that part, but it can be added to the configuration file if you have the Atmel datasheet so that you can enter the programming specifications.

You can use the following on the command line to get a list of microcontrollers supported – if you have a different programmer change the usbtiny

avrdude -c usbtiny -p abcd

(*) The AT90S2323 and ATtiny22 use the same algorithm.

(**) Flash addressing above 128 KB is not supported by all programming hardware. Known to work are jtag2, stk500v2, and bit-bang programmers.

(***) The ATtiny11 can only be programmed in high-voltage serial mode.

(****) The ISP programming protocol of the AT90S1200 differs in subtle ways from that of other AVRs. Thus, not all programmers support this device. Known to work are all direct bitbang programmers, and all programmers talking the STK500v2 protocol.

-b baudrate

Override the RS-232 connection baud rate specified in the respective programmer’s entry of the configuration file.

-B 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. Alternatively, the value might be suffixed with “Hz”, “kHz”, or “MHz”, in order to specify the bit clock frequency, rather than a period. 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 can also be set in the configuration file by using the ’default_bitclock’ keyword.

-c programmer-id

Specify the programmer to be used. AVRDUDE knows about several common programmers. Use this option to specify which one to use. The programmer-id parameter is the programmer’s id listed in the configuration file. Specify -c ? to list all programmers in the configuration file. If you have a programmer that is unknown to AVRDUDE, and the programmer is controlled via the PC parallel port, there’s a good chance that it can be easily added to the configuration file without any code changes to AVRDUDE. Simply copy an existing entry and change the pin definitions to match that of the unknown programmer. Currently, the following programmer ids are understood and supported:
To see a list of all supported programmers use avrdude -c abcd

-C config-file

Use the specified config file for configuration data. This file contains all programmer and part definitions that AVRDUDE knows about. If not specified, AVRDUDE reads the configuration file from /usr/local/etc/avrdude.conf (FreeBSD and Linux). See Appendix A for the method of searching for the configuration file for Windows.

If config-file is written as +filename then this file is read after the system wide and user configuration files. This can be used to add entries to the configuration without patching your system wide configuration file. It can be used several times, the files are read in same order as given on the command line.


Disable auto erase for flash. When the -U option with flash memory is specified, avrdude 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. Auto erase is not used for ATxmega devices as these devices can use page erase before writing each page so no explicit chip erase is required. Note however that any page not affected by the current operation will retain its previous contents.


Causes a chip erase to be executed. This will reset the contents of the flash ROM and EEPROM to the value ‘0xff’, and clear all lock bits. Except for ATxmega devices which can use page erase, it 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 ‘1’ to ‘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.

-E exitspec[,…]

By default, AVRDUDE leaves the parallel port in the same state at exit as it has been found at startup. This option modifies the state of the ‘/RESET’ and ‘Vcc’ lines the parallel port is left at, according to the exitspec arguments provided, as follows:

The ‘/RESET’ signal will be left activated at program exit, that is it will be held 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 ‘/RESET’ signal is active before powering up the MCU, so in case an external power supply is used for this MCU type, a previous invocation of AVRDUDE with this option specified is one of the possible ways to guarantee this condition.
The ‘/RESET’ line will be deactivated at program exit, thus allowing the MCU target program to run while the programming hardware remains connected.
This option will leave those parallel port pins active (i. e. high) that can be used to supply ‘Vcc’ power to the MCU.
This option will pull the ‘Vcc’ pins of the parallel port down at program exit.
This option will leave the 8 data pins on the parallel port active (i. e. high).
This option will leave the 8 data pins on the parallel port inactive (i. e. low).

Multiple exitspec arguments can be separated with commas.


Normally, AVRDUDE 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. Also, for programmers like the Atmel STK500 and STK600 which can adjust parameters local to the programming tool (independent of an actual connection to a target controller), this option can be used together with ‘-t’ to continue in terminal mode.

-i delay

For bitbang-type programmers, delay for approximately 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 AVRDUDE 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.

-l logfile

Use logfile rather than stderr for diagnostics output. Note that initial diagnostic messages (during option parsing) are still written to stderr anyway.


No-write – disables actually writing data to the MCU (useful for debugging AVRDUDE).


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.

-P port

Use port to identify the device to which the programmer is attached. Normally, the default parallel port is used, but if the programmer type normally connects to the serial port, the default serial port will be used. See Appendix A, Platform Dependent Information, to find out the default port names for your platform. If you need to use a different parallel or serial port, use this option to specify the alternate port name.

On Win32 operating systems, the parallel ports are referred to as lpt1 through lpt3, referring to the addresses 0x378, 0x278, and 0x3BC, respectively. If the parallel port can be accessed through a different address, this address can be specified directly, using the common C language notation (i. e., hexadecimal values are prefixed by 0x).

For the JTAG ICE mkII, if AVRDUDE has been built with libusb support, port may alternatively be specified as usb[:serialno]. In that case, the JTAG ICE mkII will be looked up on USB. If 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. For a trick how to find out the serial numbers of all JTAG ICEs attached to USB

As the AVRISP mkII device can only be talked to over USB, the very same method of specifying the port is required there.

For the USB programmer “AVR-Doper” running in HID mode, the port must be specified as avrdoper. Libhidapi support is required on Unix and Mac OS but not on Windows.

For the USBtinyISP, which is a simplistic device not implementing serial numbers, multiple devices can be distinguished by their location in the USB hierarchy.

For the XBee programmer the target MCU is to be programmed wirelessly over a ZigBee mesh using the XBeeBoot bootloader. The ZigBee 64-bit address for the target MCU’s own XBee device must be supplied as a 16-character hexadecimal value as a port prefix, followed by the @ character, and the serial device to connect to a second directly contactable XBee device associated with the same mesh (with a default baud rate of 9600). This may look similar to: 0013a20000000001dev/tty.serial.

For diagnostic purposes, if the target MCU with an XBeeBoot bootloader is connected directly to the serial port, the 64-bit address field can be omitted. In this mode the default baud rate will be 19200.

For programmers that attach to a serial port using some kind of higher level protocol (as opposed to bit-bang style programmers), port can be specified as net:host:port. In this case, instead of trying to open a local device, a TCP network connection to (TCP) port on host is established. Square brackets may be placed around host to improve readability for numeric IPv6 addresses (e.g. net:[2001:db8::42]:1337). 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.

Note: The ability to handle IPv6 hostnames and addresses is limited to Posix systems (by now).


Disable (or quell) output of the progress bar while reading or writing to the device. Specify it a second time for even quieter operation.


Disables the default behaviour of reading out the fuses three times before programming, then verifying at the end of programming that the fuses have not changed. If you want to change fuses you will need to specify this option, as avrdude will see the fuses have changed (even though you wanted to) and will change them back for your “safety”. This option was designed to prevent cases of fuse bits magically changing (usually called safemode).

If one of the configuration files contains a line

default_safemode = no;

safemode is disabled by default. The ‘-u’ option’s effect is negated in that case, i. e. it enables safemode.

Safemode is always disabled for AVR32, Xmega and TPI devices.


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.


Tells AVRDUDE to enter the interactive “terminal” mode instead of up- or downloading files. See below for a detailed description of the terminal mode.

-U memtype:op:filename[:format]

Perform a memory operation. Multiple ‘-U’ options can be specified in order to operate on multiple memories on the same command-line invocation. The memtype field specifies the memory type to operate on. Use the ‘-v’ option on the command line or the part command from terminal mode to display all the memory types supported by a particular device. Typically, a device’s memory configuration at least contains the memory types flash and eeprom. All memory types currently known are:

One or more bytes of RC oscillator calibration data.
The EEPROM of the device.
The extended fuse byte.
The flash ROM of the device.
The fuse byte in devices that have only a single fuse byte.
The high fuse byte.
The low fuse byte.
The lock byte.
The three device signature bytes (device ID).
The fuse bytes of ATxmega devices, N is an integer number for each fuse supported by the device.
The application flash area of ATxmega devices.
The application table flash area of ATxmega devices.
The boot flash area of ATxmega devices.
The production signature (calibration) area of ATxmega devices.
The user signature area of ATxmega devices.

The op field specifies what operation to perform:

read the specified device memory and write to the specified file
read the specified file and write it to the specified device memory
read the specified device memory and the specified file and perform a verify operation

The filename field indicates the name of the file to read or write. The format field is optional and contains the format of the file to read or write. Possible values are:

Intel Hex
Motorola S-record
raw binary; little-endian byte order, in the case of the flash ROM data
ELF (Executable and Linkable Format), the final output file from the linker; currently only accepted as an input file
immediate mode; actual byte values specified on the command line, separated by commas or spaces in place of the filename field of the ‘-U’ option. This is useful for programming fuse bytes without having to create a single-byte file or enter terminal mode. If the number specified begins with 0x, it is treated as a hex value. If the number otherwise begins with a leading zero (0) it is treated as octal. Otherwise, the value is treated as decimal.
auto detect; valid for input only, and only if the input is not provided at stdin.
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.
hexadecimal; each value will get the string 0x prepended.
octal; each value will get a 0 prepended unless it is less than 8 in which case it gets no prefix.
binary; each value will get the string 0b prepended.

The default is to use auto detection for input files, and raw binary format for output files.

Note that if filename contains a colon, the format field is no longer optional since the filename part following the colon would otherwise be misinterpreted as format.

When reading any kind of flash memory area (including the various sub-areas in Xmega devices), the resulting output file will be truncated to not contain trailing 0xFF bytes which indicate unprogrammed (erased) memory. Thus, if the entire memory is unprogrammed, this will result in an output file that has no contents at all.

As an abbreviation, the form -U filename is equivalent to specifying -U flash:w:filename:a. This will only work if filename does not have a colon in it.


Enable verbose output. More -v options increase verbosity level.


Disable automatic verify check when uploading data.

-x extended_param

Pass extended_param to the chosen programmer implementation as an extended parameter. The interpretation of the extended parameter depends on the programmer itself. See below for a list of programmers accepting extended parameters.

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