Lpc2000

> Regardless, I always found that TDO
> is floating.  If I'm understanding correctly, it should be either
> high or low at all times in debug mode since it is the JTAG data
> output.

Many times I've wished to stumble onto a PDF of the 1149.1 JTAG spec.... 
(hint, hint)....  But here's one of the better tutorials with quite a 
bit of info:

http://www.asset-intertech.com/pdfs/boundaryscan_tutorial.pdf

Turn to page 32, where they claim that TDO defaults to Hi-Z except 
"during a shift operation".  If that's true, you might have to control 
TMS and clock TCK to travel though several states to get into Shift-DR 
or Shift-IR.  While you're at it, reading out the IDCODE register 
wouldn't be too much more work, and that'd tell you for sure.  Well, 
based on the tutorial and some hands-on experiementation (or fumbling 
around) with JTAG without the official spec.

Of course, if anyone happens to know of a copy of 1149.1 just laying 
around for free on some server.....


-Paul