[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

RE: JTAG in expansion slots



> 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.
> 
See the section on Pull-ups (4.3.3) in the PCI 2.2 spec.  TDI and TMS are
supposed to be bussed and pulled up, TCK and TRST# should be bussed and
pulled down.

Whether the motherboard vendors follow the rules, is another matter....

Regards,
Andy