JTAG in expansion slots

["Olaf Birkeland" <Olaf.Birkeland@fast.no>]

Hi,

I'm developing a PCI card where we will use JTAG for production tests. I'm
considering whether to have the expansion card JTAG chain as a separate
chain, or connecting it to the JTAG port in the PCI connector. I would
appreciate some thoughts on these two:

1) If the PCI JTAG port is connected, I'm depending on the motherboard to
drive these signals properly (pullup on TDI/TMS, pulldown on TCK/TRST#) I've
so far seen two motherboards that doesn't do this (either pullups on all, or
floating!!) I can't find any requirements for motherboard implementation in
PCI 2.2 that requires pullup/-down. There is also no checkpoint for this in
the compliance checklist. The Intel PC chipset reference designs have the
pullup/-down in place though......

2) If having the cards JTAG as a separate chain, would I be loosing some
functionality? Are there any motherboards out there that would allow a JTAG
test controlled by the CPU? If not, I would probably be best off ignoring
the PCI JTAG (shorting TDI/TDO in the PCI connector)

Regards,
- Olaf


===========================================================
Olaf René Birkeland, M.Sc.    Mail:  Olaf.Birkeland@fast.no
Senior R&D Manager            Web:   http://www.fast.no/
Fast Search & Transfer ASA    Phone: +47 21 60 12 37
P.O. Box 1677 Vika            Fax:   +47 21 60 12 01
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NO-0120 Oslo, Norway

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