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Re: JTAG pins
I agree with your points. We are trying to get support from two
motherboard vendors with which we have found this problem. I'll give
them a couple of days to respond before letting the user's group know
the names of the vendors and motherboard model numbers.
Lame Brooks-G14738 wrote:
> I strongly suggest that we try to enforce the compatibility intent of
> specifications by making it widely known (first to the source) when there is
> a real problem due to a manufacturer not adhering to the spec(s). What is
> the mfg and model of the non-compliant motherboard. Distributors should
> also be informed.
> I just want the products I buy to work! -- BrooksL :)
> > -----Original Message-----
> > From: Olaf Birkeland [mailto:Olaf.Birkeland@fast.no]
> > Sent: Monday, 03 September, 2001 00:03
> > To: firstname.lastname@example.org
> > Cc: email@example.com
> > Subject: RE: JTAG pins
> > > -----Original Message-----
> > > From: firstname.lastname@example.org [mailto:email@example.com]
> > > Sent: Friday, August 31, 2001 20:18
> > > To: firstname.lastname@example.org
> > > Subject: JTAG pins
> > >
> > >
> > > Hello,
> > >
> > > I have just recently come across a fairly new motherboard
> > which has the
> > > PCI connector TMS signal pulled down to ground with a 1K resistance.
> > > This is crippling to my PCI card, since I use the JTAG signals for
> > > production test of the card (and this pulldown puts my PCI interface
> > > device into JTAG mode). This brings me to 2 questions:
> > >
> > > 1. Has anyone come across this problem and researched into the
> > > magnitude of it? Are there few or many motherboards out
> > there which are
> > > not compliant to the rev 2.2 spec, paragraph 4.3.3 --
> > requiring a pullup
> > > on TMS and TDI?
> > I've seen a lot of variation on this, ranging from incorrect
> > pull-up/down to
> > no resistors at all.
> > >
> > > 2. Are most PCI expansion cards designed without using the
> > JTAG pins of
> > > the PCI connector, hence most cards operate fine in these
> > non-compliant
> > > motherboards?
> > At least to my experience. I've opted for bringing JTAG out
> > to a separate
> > connector in my designs, leaving the PCI JTAG as is (i.e.
> > connecting TDI to
> > TDO). This makes my JTAG chain independent of whatever the
> > motherboard and
> > other expansion cards are doing. The drawback is the need for
> > a separate
> > test connector and plugging into this during production test.
> > Regards,
> > - Olaf
- RE: JTAG pins
- From: Lame Brooks-G14738 <Brooks_Lame-G14738@email.mot.com>