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Altera_Forum's avatar
Altera_Forum
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15 years ago

How to connect single REFCLK pin to rx_cruclk[3..0]?

QII says that my REFCLKp pin is not connected although clearly it is. I assume it does not like to have a single pin connected via a bus to four CRU inputs on my GXB block?

Will I need to put a PLL between the input pin and GXB CRU clock inputs in order to fan out my reference clock input?

This is for a PCIe design.

Screenshots attached.

Thanks!

2 Replies

  • Altera_Forum's avatar
    Altera_Forum
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    The issue seems to be how to connect a single input pin to multiple net members. I can't figure out how to do this schematically in the BDF file.

    In other words, I want to connect the REFCLKp pin to all rx_cruclk[3..0] member bits. Surely there must be a way to avoid to have to use four pins connected to the same external reference clock signal (especially since using a differential clock)?
  • Altera_Forum's avatar
    Altera_Forum
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    Ok, I figured this out. The input REFCLKp pin is connected to a bus named 'REFCLKp, REFCLKp, REFCLKp, REFCLKp'. This bus is then connected to the GXB block's rx_cruclk[3..0] input. See attached images.