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Re: devices not seen, fpgas not getting the clock



This is probably for devices that are behind a DEC/Intel/TI 2115x type
PCI/PCI bridge. These bridges can stop individual clocks by register
settings. You can tweak the PCI bridge register yourself, but for
getting you protoype board up running it would probably be sufficient to
move it to one of the PCI slots that are on the primary PCI bus, *before*
the PCI/PCI bridge.

Regards,
- Olaf

On Wed, 28 Jun 2000, Marco Brambilla (Wireline) wrote:

> 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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>  Marco BRAMBILLA   
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