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a new user,a strange question

Altera_Forum
Honored Contributor II
‎07-29-2010 10:52 AM
1,200 Views

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.
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Altera_Forum
Honored Contributor II
‎07-29-2010 01:06 PM
372 Views

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.

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Altera_Forum
Honored Contributor II
‎07-29-2010 02:19 PM
372 Views

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.
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