Xilinx JTAG Download Cable
On Xilinx’s site you will find 2 (maybe 3) arrangements of the same parallel download cable schematic. The first is here: http://toolbox.xilinx.com/docsan/2_1i/data/common/jtg/fig26.htm . The second comes up on Google a lot: http://www.xilinx.com/support/programr/jtag_cable.pdf. They’re the same schematic, but it’s not exactly easy to design a PCB or layout the connections without the schematic file for your CAD.
So I decided to take the time to copy it directly into CadSoft EAGLE, and release the schematic file so others can design a PCB out of it in EAGLE, or just lay it out (like me) to build it on a perf board.
Download the EAGLE schematic file here: xilinx_jtag_download_cable.sch