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

a new user,a strange question

Warning: Output pin "pre_syn.bp.PidCtrlA_Phase_i_2_" driven by bidirectional pin "LVTTLIO_D2[11]" cannot be tri-stated

who can tell me what is the mean of this?????.the"Phase_i" is register,and"LVTTLIO_D2[11]" is output pin.

2 Replies

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

    Sounds like you are trying to drive a tristate ('Z') level to an output pin. To do so, the pin must be defined as inout instead of out.

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

    FvM

    sorry for the question,i make mistake.

    the bus "LVTTLIO_D2" is already defined as inout pin.and it used as input pin.befor i read the data,i've set the "LVTTLIO_D2[11]" to "Z".i do not understand where the "output pin" is.