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Altera_Forum's avatar
Altera_Forum
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9 years ago

LVDS in Stratix iv

Hi,

I'm working on a project with a pair of high speed LVDS ports.

The FPGA board that I'm using is DE4 which is using a stratix IV

EP4SGX530 as the FPGA. How can I check if the LVDS is working?

The LVDS that I am using is made by the Quartus IPcatalog. It is

an LVDS with soft DPA SerDes for SGMII. It is runing in a frequency

of 125Mhz for the parallel and 1.25Ghz for the serial port. I can

the the transmission locked at the tx_lvds. I however can see

anything on the PHY after the LVDS. Can I slow down the speed

and connect the LVDS output back into the FPGA to check if it is

working?

Thanks,

Peter Chang

2 Replies

  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor

    --- Quote Start ---

    Hi,

    I'm working on a project with a pair of high speed LVDS ports.

    The FPGA board that I'm using is DE4 which is using a stratix IV

    EP4SGX530 as the FPGA. How can I check if the LVDS is working?

    The LVDS that I am using is made by the Quartus IPcatalog. It is

    an LVDS with soft DPA SerDes for SGMII. It is runing in a frequency

    of 125Mhz for the parallel and 1.25Ghz for the serial port. I can

    the the transmission locked at the tx_lvds. I however can see

    anything on the PHY after the LVDS. Can I slow down the speed

    and connect the LVDS output back into the FPGA to check if it is

    working?

    Thanks,

    Peter Chang

    --- Quote End ---

    Hi,

    Some experience and clarification, after hard working on the LVDS,

    are able to share with all you need. In the last question, I've asked about

    the LVDS in my last mail. There are some typos inside. Let me correct

    the whole post again below please. And some questions have answers

    that will be shown after.

    I'm working on a project with a pair of high speed LVDS ports.

    The FPGA board that I'm using is DE4, which is using a stratix IV

    EP4SGX530 FPGA. How can I check if the LVDS is working?

    Answer: I can use the HSMA loopback to check LVDS.

    The LVDS that I am using is made by the Quartus IPcatalog. It is

    an LVDS in the mode of soft CDR for SGMII. It is runing in a frequency

    of 125Mhz for the parallel and 1.25Ghz for the serial port. I can see

    the the transmission locked at the tx_lvds. I however can not see

    anything on the PHY after the LVDS. Can I slow down the speed

    and connect the LVDS output back into the FPGA to check if it is

    working?

    Answer : Yes, through HSMA loopback.

    Peter Chang
  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor

    Hi,

    The problem doesn't not totally solved yet. Even the LVDS loopback has been done.

    The LVDS for SGMII to PHY isn't as expected working well. I don't know why?

    Are there any experts who can solve the problem? PHY is now link up. But there are

    no TX LED and RX LED lighted on. It seem having no data tranmitting on PHY. A little

    confused.

    Thanks,

    Peter Chang