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Altera_Forum
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11 years ago

ALTDDIO_OUT. How to overcome restrictions on output data port?

Hello!

In the Double Data Rate I/O Megafunctions datasheet it is said, that DDR output data port of ALTDDIO_OUT ( dataout[] ) should directly feed output pins in top-level design.

But in my design I need to feed these outputs to inputs of another block inside my design.

That , of course, causes Quartus errors.

Is there a workaround for this problem?

2 Replies

  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    11 years ago

    --- Quote Start ---

    Hello!

    In the Double Data Rate I/O Megafunctions datasheet it is said, that DDR output data port of ALTDDIO_OUT ( dataout[] ) should directly feed output pins in top-level design.

    But in my design I need to feed these outputs to inputs of another block inside my design.

    That , of course, causes Quartus errors.

    Is there a workaround for this problem?

    --- Quote End ---

    DDR is meant for external interfacing only. Inside fpga there is no ddr support as you can just double your clock.
  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    11 years ago

    And you can just build it in RTL. The altddio_out is meant to call the dedicated structure built in the I/O cell.