I started this project in 2003, while working on ATmega128-based hardware setup with JTAG for programming instead of SPI. I was frustrated at how slow programming the part was with the Atmel JTAG-ICE, and stayed up one night hacking together a faster replacement programmer that used JTAG. I was able to start using the programmer the next day for JTAG programming the ATmega128′s flash, but it took a long time to build it into a full featured programmer compatible with all the parts in the AVR family. The programmer takes about 20 seconds to program the full 128kB Flash of an ATmega128 using JTAG.
I added SPI programming in addition to JTAG to make a more complete AVR programmer. A coworker started calling it the “Super Programmer”, so combining that name with the dual SPI and JTAG features, I released it as the “SP Duo”. I did a basic hardware design but Harald Kipp of egnite made a much better design and started bundling the programmer with some AVR-based Ethernut development kits. I sold the programmer through the embedded-creations.com site for a few years until the logistics of packing and shipping the product became a hassle. As of now it is only available for purchase through egnite in Germany.
The SP Duo can be purchased from egnite in Germany: egnite Shop
The most recent information on the programmer is at Ethernut: http://www.ethernut.de/en/isp/spduo.html
I am working on an Open Hardware JTAG programmer using an ATtiny85 and USB instead of RS232: Tiny AVR JTAG Programmer