convert pci express x16 to 16 pci express x1

[asa1365]

Hello friend,

I want to design a converter pci express x 16 to 16 pci express x1 .
How I connect pins PRSNT and clock?

please suggest a solve for it ?

Thank you

 

[FvM]

Presume you'll use buffers.

PCIe specification tells that "splitting of Ports into multiple Links" is an optional rather than a required feature, so you would check first if your PCIe host does support it.

 

[asa1365]

Thank you for your response.
I produce chip si53115 . can I use it as buffer for clock and prstn .
I think, it have not output for prstn ?

 

[FvM]

I thought you have been talking about the PCIe reset signal PERST# which can be just routed forward or buffered by simple CMOS buffers. PRSNT# is however a present signal for hot-plug detection, please review the PCIe card electromechanical specification. You'll probably short PRSNT1# and PRSNT2# to signal permanent presence.

 

[asa1365]

your opinion , when i use si53115 , i should connect PRSTN2 in all of pci express x1 to B81 (PRSTN)in pci express x16 ?

 

[FvM]

I really suggest to read the PCIe specification to understand the function of the PRSNT signals.

My suggestion to signal permanent presence to the host, respectively the presence signals of the individual cards are simply unconnected.

 

[asa1365]

I used si53102-A1 for create clock that produce 2 line clock for 2 pci-express x1 but it do not work correctly .
can you suggest a solve

 

[FvM]

but it do not work correctly

What exactly does not work? Clock distribution or communication with the PCIe devices? How do you test it? Does your host support the optional port splitting feature at all?

 

[asa1365]

What exactly does not work? Clock distribution or communication with the PCIe devices? How do you test it? Does your host support the optional port splitting feature at all?

Thank you for your response. I attached my schematic .please check it.
just clock 1 work correctly but clock 2 do not work.
while slot1 connect to line 0 and slot 2 connect to line1.
I test it with a pc while connect it to a card ethernet to this converter .

what is port splitting feature ?

 

[FvM]

what is port splitting feature ?

See post #2.

just clock 1 work correctly but clock 2 do not work.

How did you test? Your schematic has wrong 2 µF capacitor C3.

 

[asa1365]

Thank you for your replay.
How can check if my mother board supports this feature( port splitting)?
are there any other mistakes in my schematic design ?