Thanks for the tip. I got the cable working when i disconnected gnd and vref wires from the jtag header. I always thought i would need to have atleast gnd connected to get it working?
--David On 2010-03-22, at 3:25 PM, Andrew Dyer wrote: > On Mon, Mar 22, 2010 at 2:51 AM, David Voswinkel <[email protected]> wrote: >> Hello Armin, >> >> thanks for the advice. To get the cable respoding i alreday needed to step >> down to 3Mhz, using 6Mhz always gave me an error like: Cable doesn't >> respond, TDO seems to be stuck at 1. I tried going down in steps till >> 100Khz, this didn't change the chain scan at all. I received all the time >> the same false device id. >> >> Iam using a openocd usb cable from >> http://www.embedded-projects.net/index.php?page_id=256. The openocd usb >> design is around for some time, so i suspect the support in openocd and >> urjtag is quite mature. >> Talking about electrical issue, since iam using the openocd usb cable on my >> Digilent Nexys2 board with has also a builtin jtag which is Usbblaster >> compatible, maybe the builtin jtag interface interferes with the external >> interface. If would attach a LA the external jtag pins, how would i see that >> i get cross talk from that internal jtag device? >> > > usually we don't call that crosstalk (crosstalk is in otherwise > unconnected circuits from coupling between lines), something more like > a driver conflict. Usually you won't see it on a logic analyzer, an > oscilloscope is more useful. Often it is shown as a high or low level > that is somewhere in the transition zone between Vih and Vil > ------------------------------------------------------------------------------ Download Intel® Parallel Studio Eval Try the new software tools for yourself. Speed compiling, find bugs proactively, and fine-tune applications for parallel performance. See why Intel Parallel Studio got high marks during beta. http://p.sf.net/sfu/intel-sw-dev _______________________________________________ UrJTAG-development mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/urjtag-development
