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Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
9 years ago

output forced unknown

I am very rusty in VHDL and I have the following problem. I am testing to inputs for '1' and if either one of them is high I assign the output a '1'. However when I do this the output is always 'X'. I am sure I do something absolutely stupid, but I can't figure it out. Sorry for such a trvial problem.

Here is the screen shot

http://www.alteraforum.com/forum/attachment.php?attachmentid=13101&stc=1

And here are the wto codes, the source file and the testbench

2 Replies

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

    Hi pabloemma,

    In line 66 of test_timeTB.vhd, process "init" drives "00" to "F_DOUT_L". So if now your instance of test_time tries to drive anything other than zeros to that signal, you get a conflict, which resolves to an 'X'.

    Remove line 66 and it should be fine.

    Best regards,

    GooGooCluster