JTAG pin states

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Hi All,
I'm building a JTAG chain demultiplexer so I can control 30 identical
JTAG chains from a single point.
Can anyone confirm the quiescent (not doing anything) states of the JTAG
pins; so I know what to hold the pin levels at when a chain is not being
used.
I see that TMS, TCK & TDI have internal pull-ups, so would I place a
logical 1 on these when they're not in use? TDO is easy enough to sort
out as it just goes high Z.

Many Thanks
Andy

--
Andrew Greensted            Department of Electronics
Bio-Inspired Engineering    University of York, UK

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Re: JTAG pin states
Just for anyone who searches in the future.
It seems that TDI and TMS are usually pulled high within target devices,
however externally pulling them high (4.7k) is probably a good idea. TCK
and TDO can be left floating.

This may help:
http://support.xilinx.com/xlnx/xil_ans_display.jsp?getPagePath11%433

Andrew Greensted wrote:
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--
Andrew Greensted            Department of Electronics
Bio-Inspired Engineering    University of York, UK

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Re: JTAG pin states
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Making sure TMS stays high is a good idea, because them any glitches on
TCK will just keep (or get) the TAP controller in reset state

-Lasse


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