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 and EEPROM, and where supported by the serial programming protocol, it can program fuse and lock bits. AVRDUDE also supplies a direct instruction mode allowing one to issue any programming instruction to the AVR chip regardless of whether AVRDUDE implements that specific feature of a particular chip.

AVRDUDE can be used effectively via the command line to read or write all chip memory types (eeprom, flash, fuse bits, lock bits, signature bytes) or 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, modifing individual bytes of eeprom, programming fuse/lock bits, etc.

AVRDUDE supports the following basic programmer types: Atmel's STK500, Atmel's AVRISP and AVRISP mkII devices, Atmel's JTAG ICE (both mkI and mkII, the latter also in ISP mode), 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 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.

The STK500, JTAG ICE, avr910, and avr109/butterfly use the serial port to communicate with the PC. The STK500, 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 ROM, 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 programer 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 intented 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, JTAG, debugWire and ISP mode are supported. See below for the limitations of debugWire.

The AVR Dragon is supported in all modes (ISP, JTAG, HVSP, PP, debugWire). (High-voltage programming is not yet supported.) 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 -B bitclock option might be required to achieve a stable ISP communication.

The USBasp ISP adapter is also supported, provided AVRDUDE has been compiled with libusb support. It features a simple firwmare-only USB implementation, running on an ATmega8 (or ATmega88).