Hi all, I'm asking if there is any difference between the Xilinx JTAG III and IV??? I saw that the speed of the second is 8 time quicker than the first, but i need a JTAG cable and all the schematics are for the old one. Is it matter if i use the JTAG III instead of the PC4??? thanks
Is there any compatibility difference between The parallel JTAG PC4 and JTAG III??
Started by ●February 22, 2005
Reply by ●February 23, 20052005-02-23
"jack lalo" <firstname.lastname@example.org> schrieb im Newsbeitrag news:email@example.com...> Hi all, > I'm asking if there is any difference between the Xilinx JTAG III > and IV??? I saw that the speed of the second is 8 time quicker than > the first, but i need a JTAG cable and all the schematics are for the > old one. Is it matter if i use the JTAG III instead of the PC4??? > thanksThe good old one is just a tristate buffer. Can be easy rebuild. But you should add a RC-filter and two schmitt triggers in from of the TCK/CCLK line, since the signal from the parallel port might by noisy. Another point is, that the PC-III is only recommended with IO voltages of 5/3.3V. 2.5 might work or not. PC-IV works down to 1.5, AFAIK. And its faster, since it uses (years too late) ECP mode to transfer 8 bit of data and serialize them on the POD. Some yaers ago I did my own download cable design, using a 32 macrocell coolrunner and own control software. Downloading was at an instant. BING!! Why the hell has noone already done something like this and sells them? Especially for the big Virtex-II'n stuff life would be so much easier. Regards Falk P.S. I can email you the modified schematics of the PC-III if you like. Drop me a mail.