2.1 Option Descriptions

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 option tells AVRDUDE what part (MCU) is connected to the programmer. The partno parameter is the part’s id listed in the configuration file. To see a list of currently supported MCUs use ? as partno, which will, for each part, print its id; its official part name; alternative names, if any; and the list of available programming interfaces. In connection with -v, this will also print a table of variant part names with the package code and some absolute maximum ratings. The part id, their official part name, the listed alternative names or any of the full variant part names can be used to specify a part with the -p option. 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. If -p ? is specified with a specific programmer, see -c below, then only those parts are output that the programmer expects to be able to handle, together with the programming interface(s) that can be used in that combination. In reality there can be deviations from this list, particularly if programming is directly via a bootloader. See List of Parts for a full and detailed listing of supported parts.

-p wildcard/flags

Run developer options for MCUs that are matched by wildcard. Whilst their main use is for developers some flags can be of utility for users, e.g., avrdude -p m328p/S outputs AVRDUDE’s understanding of ATmega328P MCU properties; for more information run avrdude -p x/h.

-b baudrate

Override the RS-232 connection baud rate specified in the respective programmer’s baudrate entry of the configuration file or defined by the default_baudrate entry in your ~/.config/avrdude/avrdude.rc or ~/.avrduderc configuration file if no baudrate entry was provided for this programmer.

-B bitclock

Specify the bit clock period for the JTAG, PDI, TPI, UPDI, or ISP interface. 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. Some programmers default their bit clock value to a 1 microsecond bit clock period, suitable for target MCUs running at 4 MHz clock and above. Slower MCUs need a correspondingly higher bit clock period. Some programmers reset their bit clock value to the default value when the programming software signs off, whilst others store the last used bit clock value. It is recommended to always specify the bit clock if read/write speed is important. You can use the ’default_bitclock’ keyword in your ~/.config/avrdude/avrdude.rc or ~/.avrduderc configuration file to assign a default value to keep from having to specify this option on every invocation.

Note that some official Microchip programmers store the bitclock setting and will continue to use it until a different value is provided. This applies to 2nd generation programmers (AVRISPmkII, AVR Dragon, JTAG ICE mkII, STK600) and 3rd generation programmers (JTAGICE3, Atmel ICE, Power Debugger). 4th generation programmers (PICkit 4, MPLAB(R) SNAP) will store the last user-specified bitclock until the programmer is disconnected from the computer.

-c programmer-id

Specify the programmer to be used. AVRDUDE knows about quite a few programmers. 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 but related to a known programmer there is some chance that it can be added to the configuration file without any code changes to AVRDUDE: copy a similar entry and change those features that differ to match that of the unknown programmer. If -c ? is specified with a specific part, see -p above, then only those programmers are output that expect to be able to handle this part, together with the programming interface(s) that can be used in that combination. In reality there can be deviations from this list, particularly if programming is directly via a bootloader. See List of Programmers for a full and detailed listing of known programmers.

-c wildcard/flags

Run developer options for programmers that are matched by wildcard. Whilst their main use is for developers some flags can be of utility for users, e.g., avrdude -c usbtiny/S shows AVRDUDE’s understanding of usbtiny’s properties; for more information run avrdude -c x/h.

-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 looks for the configuration file in the following two locations:

1. <directory from which application loaded>/../etc/avrdude.conf
2. <directory from which application loaded>/avrdude.conf

If not found there, the lookup procedure becomes platform dependent. On FreeBSD and Linux, AVRDUDE looks at /usr/local/etc/avrdude.conf. See Appendix A for the method of searching on 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.

-N

Do not load the personal configuration file that is usually located at ~/.config/avrdude/avrdude.rc, ~/.avrduderc or in the same directory as the avrdude executable.

-A

Disable the automatic removal of trailing-0xFF sequences in file input that is to be programmed to flash and in AVR reads from flash memory. Normally, trailing 0xFFs can be discarded, as flash programming requires the memory be erased to 0xFF beforehand. -A should be used when the programmer hardware, or bootloader software for that matter, does not carry out chip erase and instead handles the memory erase on a page level. The popular Arduino bootloader exhibits this behaviour; for this reason -A is engaged by default when specifying -c arduino.

-D

Disable auto-erase for flash. When the -U option for writing to any 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 parts nor for the UPDI (AVR8X family) parts as these can use page erase before writing each page so no explicit chip erase is required. Note, however, that any flash page not affected by the current operation will retain its previous contents. Setting -D implies -A.

-e

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 and UPDI (AVR8X family) devices, all of 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. This option carries out the chip erase at the beginning, before any of the -U, -T or -t options are processed. If a chip erase is required in at a certain position within the sequence of -U, -T or -t options it is recommended to use -T erase instead which is processed in the given command line order.

In absence of an explicit -e or -D option avrdude tries to augur from the command line whether or not the chip should be auto-erased at the beginning. If avrdude detects a -U command that writes to flash then auto-erase will be carried out before any other programming unless a -T erase commad has been detected beforehand and unless flash is read before writing to it. For the purpose of this analysis any terminal command is considered to possibly read flash.

Note that for reprogramming EEPROM 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[,…]

Pass exitspec to the programmer. The interpretation of the exitspec parameter depends on the programmer itself. See below for a list of programmers accepting exitspec parameter options or issue avrdude -E help ... to see the options for the programmer.

Multiple exitspec options can be separated with commas.

-F

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. Moreover, the option allows to continue despite failed initialization of connection between a programmer and a target.

-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.

-n

No-write: disables writing data to the MCU whilst processing -U (useful for debugging AVRDUDE). The terminal mode continues to write to the device.

-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.

-P port

Use port to identify the connection through which the programmer is attached. This can be a parallel, serial, spi or linuxgpio connection. The programmer normally specifies the connection type; in absence of a -P specification, system-dependent default values default_parallel, default_serial, default_spi, or default_linuxgpio from the configuration file are used. If you need to use a different port, use this option to specify the alternate port name.

If avrdude has been configured with libserialport support, a serial port can be specified using a predefined serial adapter type in avrdude.conf or .avrduderc, e.g., ch340 or ft232r. If more than one serial adapter of the same type is connected, they can be distinguished by appending a serial number, e.g., ft232r:12345678. Note that the USB to serial chip has to have a serial number for this to work. Avrdude can check for leading and trailing serial number matches as well. In the above example, ft232r:1234 would also result in a match, and so would ft232r:...5678. If the USB to serial chip is not known to avrdude, it can be specified using the hexadecimal USB vendor ID, hexadecimal product ID and an optional serial number, following the serial number matching rules described above, e.g., usb:0x2341:0x0043 or usb:2341:0043:12345678. To see a list of currently plugged-in serial ports use -P ?s. In order to see a list of all possible serial adapters known to avrdude use -P ?sa.

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, see Example Command Line Invocations.

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 more information about AVR-Doper see https://www.obdev.at/products/vusb/avrdoper.html.

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 USBasp, multiple devices can be distinguished by either USB connection or serial number. See the respective Troubleshooting entry for examples.

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).

-r

Opens the serial port at 1200 baud and immediately closes it, waits 400 ms for each -r on the command line and then establishes communication with the programmer. This is commonly known as a "1200bps touch", and is used to trigger programming mode for certain boards like Arduino Leonardo, Arduino Micro/Pro Micro and the Arduino Nano Every. Longer waits, and therefore multiple -r options, are sometimes needed for slower, less powerful hosts.

-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.

-s, -u

These options used to control the obsolete "safemode" feature which is no longer present. They are silently ignored for backwards compatibility.

-T cmd

Run terminal line cmd when it is its turn in relation to other -t interactive terminals, -T terminal commands and -U memory operations. Except for the simplest of terminal commands the argument cmd will most likely need to be set in quotes, see your OS shell manual for details. See below for a detailed description of all terminal commands.

-t

Tells AVRDUDE to run an interactive terminal when it is its turn in relation to other -t interactive terminals, -T terminal commands and -U memory operations.

-U memory:op:filename[:format]

Perform a memory operation when it is its turn in relation to other -t interactive terminals, -T terminal commands and -U memory operations. The memory field specifies the memory type to operate on. From version 8.0 the memory field can also be a comma-separated list of memories, eg, flash,eeprom; also, Intel Hex or Motorola S-Record files generated by AVRDUDE can store multiple memories. The special memory ALL expands to all memories that a part has while all expands to all memories with exception of sub-memories. etc is the same as all; this can be used to change the order in which memories are written to or read from file, eg, signature,etc is a list of all memories such that the signature memory comes first. It is possible to remove a memory from the list so far by preceding a minus or backslash, eg, all,-calibration. Use the ‘-T part’ option on the command line or the part command in the interactive terminal to display all the memories supported by a particular device.

Typically, a device’s memory configuration at least contains the memory types flash, eeprom, signature and lock, which is sometimes known as lockbits. The signature memory contains the three device signature bytes, which should be, but not always are, unique for the part. The lock memory of one or four bytes typically details whether or not external reading/writing of the flash memory, or parts of it, is allowed. After restricting access via the lock memory, often the only way to unlock memory is via a chip erase. Parts will also typically have fuse bytes, which are read/write memories for configuration of the device and calibration memories that typically contain read-only factory calibration values.

The flash memory, being physically implemented as NOR-memory, is special in the sense that it is normally only possible to program bits to change from 1 to 0. Before reprogramming takes place normally flash memory has to be erased. Older parts would only offer a chip erase to do so, which also erases EEPROM unless a fuse configuration preserves its contents. If AVRDUDE detects a -U option that writes to a flash memory it might automatically trigger a chip erase for these older parts. See the description of auto-erase under the -e option above. ATxmegas or UPDI parts (AVR8X family) offer a page erase, and AVRDUDE takes advantage of that by erasing pages before programming them unless -e (chip erase) or -D (do not erase before writing) was requested. It should be noted that in absence of the -e chip erase option any ATxmega or UPDI flash pages not affected by the programming will retain their previous content.

See List of Memories for a complete list of memories that AVR devices can have.

The op field specifies what operation to perform:

r

read device memories and write to the specified file

w

read data from the specified file and write to the device memories in the list; read-only memories in a memory list are skipped, as are fuses and lock bits when the programmer is a bootloader; writing to single read-only memories fails only if the contents differs between the file and memory

v

read data from both the device and the specified file and perform a verify

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:

i

Intel Hex

I

Intel Hex with comments on reading from, and tolerance of checksum errors, writing to the AVR

s

Motorola S-Record

r

raw binary; little-endian byte order, in the case of the flash data

e

ELF (Executable and Linkable Format), the final output file from the linker; currently only accepted as an input file

m

immediate mode; actual byte values are 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.

a

auto detect; valid for input only, and only if the input is not provided at stdin.

d

decimal; this and the following formats 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.

h

hexadecimal; each value will get the string 0x prepended.

o

octal; each value will get a 0 prepended unless it is less than 8 in which case it gets no prefix.

b

binary; each value will get the string 0b prepended.

When used as input, the m, d, h, o and b formats will use the same code for reading lists of numbers separated by white space and/or commas. The read routine handles decimal, hexadecimal, octal or binary numbers on a number-by-number basis, and the list of numbers can therefore be of mixed type. In fact the syntax, is the same as for data used by the terminal write command, i.e., the file’s input data can also be 2-byte short integers, 4-byte long integers or 8-byte long long integers, 4-byte floating point numbers, 8-byte double precision numbers, C-type strings with a terminating nul or C-like characters such as '\t'. Numbers are written as little endian to memory. When using 0x hexadecimal or 0b binary input leading zeros are used to determine the size of the integer, e.g., 0x002a will occupy two bytes and write a 0x2a to memory followed by 0x00, while 0x01234 will occupy 4 bytes. See the description of the terminal write command for more details.

In absence of an explicit file format, the default is to use auto detection for input files, raw binary format for output files from a single memory read and Intel Hex with comments when an output file is generated from a list of memories. Note that while AVRDUDE will generate a single output file from a memory list for all formats with the exception of elf (:e) it only recognises Intel hex (:I or :i), Motorola S-Record (:s) or elf files (:e, generated by the compiler) as valid multi-memory files when reading a file for verifying or writing memories. Note also that if a filename contains a colon as penultimate character the format field is no longer optional since the last character 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. This behaviour can be overridden with the -A option.

As an abbreviation, the form -U filename is equivalent to specifying -U flash:w:filename:a or -U application:w:filename:a for ATxmegas. This will only work if filename does not have a pair of colons in it that sandwich a single character as otherwise the first part might be interpreted as memory, and the single character as memory operation.

-v

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

-V

Disable automatic verify check when writing data to the AVR with -U.

-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 or issue avrdude -x help ... to see the extended options of the chosen programmer.

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