AVRDUDE

A program for downloading/uploading AVR microcontroller flash, EEPROM and more

for AVRDUDE, Version 8.0, 23 July 2025

Use https://github.com/avrdudes/avrdude/issues to report bugs and ask questions.

Copyright © Hans Eirik Bull, Brian S. Dean, Stefan Rüger and Jörg Wunsch

Permission is granted to make and distribute verbatim copies of this manual provided the copyright notice and this permission notice are preserved on all copies.

Permission is granted to copy and distribute modified versions of this manual under the conditions for verbatim copying, provided that the entire resulting derived work is distributed under the terms of a permission notice identical to this one.

Permission is granted to copy and distribute translations of this manual into another language, under the above conditions for modified versions, except that this permission notice may be stated in a translation approved by the Free Software Foundation.

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1 Introduction

AVRDUDE - AVR Downloader Uploader - is a program for downloading and uploading the on-chip memories of Atmel’s AVR microcontrollers. It can program the Flash, EEPROM, and where supported by the programmer, lock bits, fuses that hold the microcontroller’s configuration and other memories that the part might have.

AVRDUDE can be used via the command line to read or write chip memories (eeprom, flash, fuses, lock bits) and read memories such as signature or calibration bytes; the same can be achieved via an interactive terminal mode. Using AVRDUDE from the command line works well for programming the entire memory of the chip from the contents of a file, while interactive mode is useful for exploring memory contents, modifying individual bytes of eeprom, programming fuse/lock bits, etc.

Programming a microcontroller either requires a physical programmer that sits between the target chip and the PC running AVRDUDE, or a bootloader program on the target chip that is then directly connected to the PC to be served by AVRDUDE. Currently, AVRDUDE knows about and 167 programmers, though not every programmer can deal with every part. One noteworthy programmer is dryrun, which allows one to explore the AVRDUDE command-line and terminal without needing to have, or connect, a real physical programmer. Similarly, dryboot allows exploring how to communicate with a bootloader without connecting an AVR part.

AVRDUDE supports the following basic programmer types: Atmel’s STK500, Atmel’s AVRISP and AVRISP mkII devices, Atmel’s STK600, Atmel’s JTAG ICE (the original one, mkII, and 3), appnote avr910, appnote avr109 (including the AVR Butterfly), serial bit-bang adapters, and the PPI (parallel port interface). PPI represents a class of simple programmers where the programming lines are directly connected to the PC parallel port. Several pin configurations exist for several variations of the PPI programmers, and AVRDUDE can be configured to work with them by either specifying the appropriate programmer on the command line or by creating a new entry in its configuration file. All that’s usually required for a new entry is to tell AVRDUDE which pins to use for each programming function.

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.

If you happen to have a Linux system with at least 4 hardware GPIOs available (like almost all embedded Linux boards) you can do without any additional hardware - just connect them to the SDO, SDI, RESET and SCK pins of the AVR’s SPI interface and use the linuxgpio programmer type. Older boards might use the labels MOSI for SDO and MISO for SDI. It bitbangs the lines using the Linux sysfs GPIO interface. Of course, care should be taken about voltage level compatibility. Also, although not strictly required, it is strongly advisable to protect the GPIO pins from overcurrent situations in some way. The simplest would be to just put some resistors in series or better yet use a 3-state buffer driver like the 74HC244. Have a look at https://kolev.info/blog/2013/01/06/avrdude-linuxgpio/ for a more detailed tutorial about using this programmer type.

Under a Linux installation with direct access to the SPI bus and GPIO pins, such as would be found on a Raspberry Pi, the “linuxspi” programmer type can be used to directly connect to and program a chip using the built in interfaces on the computer. The requirements to use this type are that an SPI interface is exposed along with one GPIO pin. The GPIO serves as the reset output since the Linux SPI drivers do not hold chip select down when a transfer is not occuring and thus it cannot be used as the reset pin. A readily available level translator should be used between the SPI bus/reset GPIO and the chip to avoid potentially damaging the computer’s SPI controller in the event that the chip is running at 5V and the SPI runs at 3.3V. The GPIO chosen for reset can be configured in the avrdude configuration file using the reset entry under the linuxspi programmer, or directly in the port specification. An external pull-up resistor should be connected between the AVR’s reset pin and Vcc. If Vcc is not the same as the SPI voltage, this should be done on the AVR side of the level translator to protect the hardware from damage.

On a Raspberry Pi, header J8 provides access to the SPI and GPIO lines.

Typically, pins 19, 21, and 23 are SPI SDO, SDI, and SCK, while pins 24 and 26 would serve as CE outputs. So, close to these pins is pin 22 as GPIO25 which can be used as /RESET, and pin 25 can be used as GND.

A typical programming cable would then look like:

(Mind the 3.3 V voltage level of the Raspberry Pi!)

The -P portname option defaults to /dev/spidev0.0:/dev/gpiochip0 for this programmer.

The STK500, JTAG ICE, avr910, and avr109/butterfly use the serial port to communicate with the PC. The STK600, JTAG ICE mkII/3, AVRISP mkII, USBasp, avrftdi (and derivatives), and USBtinyISP programmers communicate through the USB, using libusb as a platform abstraction layer. The avrftdi adds support for the FT2232C/D, FT2232H, and FT4232H devices. These all use the MPSSE mode, which has a specific pin mapping. Bit 0 (the lsb of the byte in the config file) is SCK. Bit 1 is SDO, and Bit 2 is SDI. Bit 3 usually reset. The 2232C/D parts are only supported on interface A, but the H parts can be either A or B (specified by the usbdev config parameter). The STK500, STK600, JTAG ICE, and avr910 contain on-board logic to control the programming of the target device. The avr109 bootloader implements a protocol similar to avr910, but is actually implemented in the boot area of the target’s flash, as opposed to being an external device. The fundamental difference between the two types lies in the protocol used to control the programmer. The avr910 protocol is very simplistic and can easily be used as the basis for a simple, home made programmer since the firmware is available online. On the other hand, the STK500 protocol is more robust and complicated and the firmware is not openly available. The JTAG ICE also uses a serial communication protocol which is similar to the STK500 firmware version 2 one. However, as the JTAG ICE is intended to allow on-chip debugging as well as memory programming, the protocol is more sophisticated. (The JTAG ICE mkII protocol can also be run on top of USB.) Only the memory programming functionality of the JTAG ICE is supported by AVRDUDE. For the JTAG ICE mkII/3, JTAG, debugWIRE and ISP mode are supported, provided it has a firmware revision of at least 4.14 (decimal). See below for the limitations of debugWIRE. For ATxmega devices, the JTAG ICE mkII/3 is supported in PDI mode (Xmega parts), provided it has a revision 1 hardware and firmware version of at least 5.37 (decimal).

The Atmel-ICE (ARM/AVR) is supported (JTAG, PDI, debugWIRE, ISP, UPDI).

Atmel’s XplainedPro boards, using EDBG protocol (CMSIS-DAP compliant), are supported by the “jtag3” programmer type.

Atmel’s XplainedMini boards, using mEDBG protocol, are also supported by the “jtag3” programmer type.

The AVR Dragon is supported in all modes (ISP, JTAG, PDI, 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 and PDI 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 -B bitclock option might be required to achieve a stable ISP communication. For ATxmega devices, the AVR Dragon is supported in PDI mode, provided it has a firmware version of at least 6.11 (decimal).

Wiring boards (e.g. Arduino Mega 2560 Rev3) are supported, utilizing STK500 V2.x protocol, but a simple DTR/RTS toggle to set the boards into programming mode. The programmer type is “wiring”. Note that the -D option will likely be required in this case, because the bootloader will rewrite the program memory, but no true chip erase can be performed.

Serial bootloaders that run a skeleton of the STK500 1.x protocol are supported via their own programmer type specification “arduino”. This programmer works for the Arduino Uno Rev3 or any AVR that runs the Optiboot bootloader. The number of connection retry attempts can be specified as an extended parameter. See the section on extended parameters below for details.

Urprotocol is a leaner version of the STK500 1.x protocol that is designed to be backwards compatible with STK500 v1.x; it allows bootloaders to be much smaller, e.g., as implemented in the urboot project https://github.com/stefanrueger/urboot. The programmer type “urclock” caters for these urboot bootloaders. Owing to its backward compatibility, bootloaders that can be served by the arduino programmer can normally also be served by the urclock programmer. This may require specifying the size of (to AVRDUDE) unknown bootloaders in bytes using the -x bootsize=<n> option, which is necessary for the urclock programmer to enable it to protect the bootloader from being overwritten. If an unknown bootloader has EEPROM read/write capability then the option -x eepromrw informs avrdude -c urclock of that capability.

The BusPirate is a versatile tool that can also be used as an AVR programmer. A single BusPirate can be connected to up to 3 independent AVRs. See the section on extended parameters below for details.

The USBasp ISP, USBtinyISP and CH341A adapters are also supported, provided AVRDUDE has been compiled with libusb support. They former two feature simple firmware-only USB implementations, running on an ATmega8 (or ATmega88), or ATtiny2313, respectively. CH341A programmers connect directly to the AVR target. Their SPI bit clock is approximately 1.7 MHz and cannot be changed. As a consequence, the AVR target must have a CPU frequency of 6.8 MHz or more: factory-set AVR parts, which typically run on an internal oscillator between 1 MHz and 1.6 MHz, cannot be programmed using -c ch341a.

The Atmel DFU bootloader is supported in both, FLIP protocol version 1 (AT90USB* and ATmega*U* devices), as well as version 2 (Xmega devices). See below for some hints about FLIP version 1 protocol behaviour.

The MPLAB(R) PICkit 4 and MPLAB(R) SNAP are supported in JTAG, TPI, ISP, PDI and UPDI mode. The Curiosity Nano board is supported in UPDI mode. It is dubbed “PICkit on Board”, thus the name pkobn_updi. The MPLAB(R) PICkit 5 is currently only supported in UPDI mode.

SerialUPDI programmer implementation is based on Microchip’s pymcuprog (https://github.com/microchip-pic-avr-tools/pymcuprog) utility, but it also contains some performance improvements included in Spence Konde’s DxCore Arduino core (https://github.com/SpenceKonde/DxCore). In a nutshell, this programmer consists of simple USB-to-UART adapter, diode and couple of resistors. It uses serial connection to provide UPDI interface. See section SerialUPDI Programmer for more details and known issues.

The jtag2updi programmer is supported, and can program AVRs with a UPDI interface. Jtag2updi is just a firmware that can be loaded onto an AVR, which enables it to interface with avrdude using the jtagice mkii protocol via a serial link (https://github.com/ElTangas/jtag2updi).

The Micronucleus bootloader is supported for both protocol version V1 and V2. As the bootloader does not support reading from flash memory, use the -V option to prevent AVRDUDE from verifying the flash memory. See the section on extended parameters below for Micronucleus specific options.

The Teensy bootloader is supported for all AVR boards. As the bootloader does not support reading from flash memory, use the -V option to prevent AVRDUDE from verifying the flash memory. See the section on extended parameters below for Teensy specific options.

List of Programmers holds a full listing of known programmers.

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