This is the README file for USBasp.

USBasp is a USB in-circuit programmer for Atmel AVR controllers. It simply
consists of an ATMega48 or an ATMega8 and a couple of passive components.
The programmer uses a firmware-only USB driver, no special USB controller
is needed.

Features:
- Works under multiple platforms. Linux, Mac OS X and Windows are tested.
- No special controllers or smd components are needed.
- Programming speed is up to 5kBytes/sec.
- SCK option to support targets with low clock speed (< 1,5MHz).
- Planned: serial interface to target (e.g. for debugging).


LICENSE

USBasp is distributed under the terms and conditions of the GNU GPL version
2 (see "firmware/usbdrv/License.txt" for details).

USBasp is built with AVR USB driver by OBJECTIVE DEVELOPMENT GmbH. See
"firmware/usbdrv/" for further information.


LIMITATIONS

Hardware:
This package includes a circuit diagram. This circuit can only be used for
programming 5V target systems. For other systems a level converter is needed.

Firmware:
The firmware dosn't support USB Suspend Mode. A bidirectional serial
interface to slave exists in hardware but the firmware doesn't support it yet.


USE PRECOMPILED VERSION

Firmware:
Flash "bin/firmware/usbasp.atmega48.xxxx-xx-xx.hex" or
"bin/firmware/usbasp.atmega8.xxxx-xx-xx.hex" to the used controller with a
working programmer (e.g. with avrdude, uisp, ...). Set jumper J2 to activate
USBasp firmware update function.
You have to change the fuse bits for external crystal (see "make fuses").
# TARGET=atmega8    HFUSE=0xc9  LFUSE=0xef
# TARGET=atmega48   HFUSE=0xdd  LFUSE=0xff

Windows:
Start Windows and connect USBasp to the system. When Windows asks for a
driver, choose "bin/win-driver". On Win2k and WinXP systems, Windows will
warn that the driver is is not 'digitally signed'. Ignore this message and
continue with the installation.
Now you can run avrdude. Examples:
1. Enter terminal mode with an AT90S2313 connected to the programmer:
   avrdude -c usbasp -p at90s2313 -t
2. Write main.hex to the flash of an ATmega8:
   avrdude -c usbasp -p atmega8 -U flash:w:main.hex

Setting jumpers:
J1 Power target
   Supply target with 5V (USB voltage). Be careful with this option, the
   circuit isn't protected against short circuit!
J2 Jumper for firmware upgrade (not self-upgradable)
   Set this jumper for flashing the ATMega(4)8 of USBasp with another working
   programmer.
J3 SCK option
   If the target clock is lower than 1,5 MHz, you have to set this jumper.
   Then SCK is scaled down from 375 kHz to about 8 kHz.


BUILDING AND INSTALLING FROM SOURCE CODE

Firmware:
To compile the firmware
1. install the GNU toolchain for AVR microcontrollers (avr-gcc, avr-libc),
2. change directory to firmware/
3. run "make main.hex"
4. flash "main.hex" to the ATMega(4)8. E.g. with uisp or avrdude (check
the Makefile option "make flash"). To flash the firmware you have
to set jumper J2 and connect USBasp to a working programmer.
You have to change the fuse bits for external crystal, (check the Makefile
option "make fuses").

Software (avrdude):
AVRDUDE supports USBasp since version 5.2. 
1. install libusb: http://libusb.sourceforge.net/
2. get latest avrdude release: http://download.savannah.gnu.org/releases/avrdude/
3. cd avrdude-X.X.X
5. configure to your environment:
   ./bootstrap (I had to comment out the two if-blocks which verify the
                installed versions of autoconf and automake)
   ./configure
6. compile and install it:
   make 
   make install

Notes on Windows (Cygwin):
Download libusb-win32-device-bin-x.x.x.x.tar.gz from
http://libusb-win32.sourceforge.net/ and unpack it.
-> copy lib/gcc/libusb.a to lib-path
-> copy include/usb.h to include-path
cd avrdude
./configure LDFLAGS="-static" --enable-versioned-doc=no
make

Notes on Darwin/MacOS X:
after "./configure" I had to edit Makefile:
change "avrdude_CPPFLAGS" to "AM_CPPFLAGS"
(why is this needed only on mac? bug in configure.ac?)


FILES IN THE DISTRIBUTION

Readme.txt ...................... The file you are currently reading
firmware ........................ Source code of the controller firmware
firmware/usbdrv ................. AVR USB driver by Objective Development
firmware/usbdrv/License.txt ..... Public license for AVR USB driver and USBasp
circuit ......................... Circuit diagram in PDF and EAGLE format
bin ............................. Precompiled programs
bin/win-driver .................. Windows driver
bin/firmware .................... Precompiled firmware


MORE INFORMATION

For more information on USBasp and it's components please visit the
following URLs:

USBasp .......................... http://www.fischl.de/usbasp/

Firmware-only AVR USB driver .... http://www.obdev.at/products/avrusb/
avrdude ......................... http://www.nongnu.org/avrdude/
libusb .......................... http://libusb.sourceforge.net/
libusb-win32 .................... http://libusb-win32.sourceforge.net/


2009-02-28 Thomas Fischl <tfischl@gmx.de>
http://www.fischl.de
