• TI Thinks Resolved

DS80PCI800: DS80PCI800: can not pass PCIE gen 3 eye testing

Intellectual 700 points

Replies: 8

Views: 157

Part Number: DS80PCI800

Hi Team,

DS80PCI800 used on PCI-E riser card applications
When testing the eye diagram and found that PCI-E GEN1 can pass but GEN3 can't pass.

Please refer attached files and help how to adjust the signal to pass GEN3.

Measure the results of PCI-E signal measurements.
Attachment instructions:
Original P0_Math1.html --> Original profile
Original P10_Math1.html --> Original profile

P0 failed eye diagram

P10 failure eye diagram

Adjust EQA1/EQB1=0, EQA0/EQB0=0 to set the result after measurement.

PCIE GEN3 Preset0 mode test eye have open

PCIE GEN3 Preset10 mode test still eye closed

Attachment instructions:

L0P0_Math1.html & L0P0_Math1.html --> Modified profile

Please help how to adjust the signal can pass GEN3.

thanks

Kevin

L0P0_Math1.htmlL0P10_Math1.html

original P0_Math1.htmloriginal P10_Math1.html

DS80PCI800 SCH.pdf

  • Hi Kevin,

    The DS80PCI800 will not be able to pass open eye waveforms with all Tx Presets.  In your application P0 (nominal -6dB) is producing an open eye and a slight amount of overequalization with the minimum DS80PCI800 equalization settings.  It is likely that other presets (P2 and P1) will also produce an open eye.  P3 and P4 will likely need a slight increase in DS80PCI800 equalization to produce a similar eye opening. 

    P10 is rarely going to produce an open eye.  It is primarily used to test the Transmit equalization levels only.

    You could switch over to the DS80PCI810 and more of the Tx presets could achieve an open eye since this newer device has improved linearity and lower overall gain which would work well in this application.

    Regards,

    Lee

  • In reply to Lee Sledjeski:

    Hi Lee,

    This's project to be mass-produced.

    Is the DS80PCI810 a direct replacement and not need change the BOM?

    Is there any suggestion for EQ settings?

    thanks

    Kevin

  • In reply to Kevin.Peng:

    Hi Lee,

    I have some confusing, the GEN3 P10 is a standard test item. if this P10 can not open eye,
    Does that mean that the DS80PCI800 does not support P10 pass item?
    If yes, is there a statement document?
    Because this is a mass production project, it is somewhat difficult to change parts.

    thanks

    Kevin

  • In reply to Kevin.Peng:

     

    Hi Lee,

    Because this case urgently needs to be solved!

    How does the DS80PCI800 improve the P10 mode open eye?
    If the DS80PCI810 is recommended to replace, does it mean that the DS80PCI800 is a bug?

    thanks

    Kevin

  • In reply to Kevin.Peng:

    Hi Kevin,

    The DS80PCI800 is not broken.  It will meet the eye requirements with several Tx Presets.  P10 is not considered a useful Tx equalization for an actual system implementation.

    This text is from the CEM specification.

    Base Specification. A motherboard must meet eye diagram requirements in Chapter 9 at 8.0 GT/s and 16.0 GT/s on each lane with one or more preset equalization setting.

    A system board shall meet the following additional rules for this specification:

    •  The system board initial TX preset at 8.0 GT/s shall be P1, P7, or P8.
    • If the equivalent of the ps21 parameter defined in the PCI Express Base Specification, measured at data rates of 8.0 GT/s at the end of the 5.0 GT/s System-Board Test Channel without de-embedding shows a loss of more than 12 dB, then the system board initial TX preset at 8.0 GT/s shall be P7 or P8.

     

     

    Regards,

    Lee

  • In reply to Lee Sledjeski:

    Hi Lee

    Today, I confirm that the customer is using the DS80PCI810NJY unit.

    Schematic is marked incorrectly and not DS80PCI800. I'm a bit confused, sorry.
    As shown in the photo


    Now using the DS80PCI810 for Riser Card, because not recognize the external card when insert the Riser Card.

    If do not install the Riser Card, only use the PCI-E slot of the motherboard can to recognize the external card.
    Therefore,To measure the P10 mode found without opening eyes.
    How can the DS80PCI810 be adjusted to open eyes through P10 mode?
    please help

    thanks

    Kevin

  • In reply to Kevin.Peng:

    Kevin,

    Using the DS80PCI810 should make things easier.

    Without knowing the channel attenuation around the DS80PCI810 I would start using these settings.

    ENSMB = 0

    EQA/B = 0 (minimum)

    VODA1/VODB1 = 1

    VODA0/VODB0 = 0  (Level 6)

    For SMBus Slave configuration:

    ENSMB = 1

    Write Register 0x06 = 18'h

    Write Registers 0x0F, 0x16, 0x1D, 0x24, 0x2C, 0x33, 0x3A, 0x41 = 00'h

    Write Registers 0x11, 0x18, 0x1F, 0x26, 0x2E, 0x35, 0x3C, 0x43 = 00'h  

  • In reply to Lee Sledjeski:

    Hi Kevin,

    Did you try the configuration settings I sent?

    Regards,

    Lee