Re: devices not seen, fpgas not getting the clock

["Peter Marek" <peter.marek@marekmicro.de>]

Marco,

what you observe is something quite normal for modern PCs: State of the art
clock generators provide an interface to stop PCI clocks, usually via a I2C
or SMB interface. The device may make use of that feature and turn off the
clock for unpopulated slots.


regards,


Peter Marek
General Director
MarekMicro GmbH
Kropfersrichter Str. 6-8
D-92237 Sulzbach-Rosenberg
Germany
Phone: 049 - 9661 - 908 - 210
Fax:      049 - 9661 - 908 - 100
----- Original Message -----
From: Marco Brambilla (Wireline) <marco-tpa.brambilla@st.com>
To: <pci-sig@znyx.com>
Sent: Wednesday, June 28, 2000 4:57 PM
Subject: devices not seen, fpgas not getting the clock


> Hi all,
>
> As someone else on the list, I too had some issues with clock not seen
> by fpgas.
>
> In our case we have many HP PCs which are working fine.
> In only one PC (a P3 500) we saw that during the initial boot phase the
> clock is present on all 3 PCI slots on the motherboard.
>
> After some seconds (5 to 30) the clock remains good on populated slots,
> while it is removed from empty slots.
> At least this is what our lab people told me.
>
> The PC is thus fully functional, but we have a development board on
> which our chip is implemented in fpga.
> For debugging reasons we cannot program the FPGA from the external
> memory, but from the jtag cable.
> This means that our board can never be seen by the motherboard, because
> at startup it was not operating, so the clock is removed from the slot.
>
> Has anyone ever heard of such a behaviour ?
> Is this "clock removing" feature really present ? (and can it be
> disabled) ?
>
> Thanks for any advice.
>
> Marco Brambilla
>
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