Tristate outputs - how to?

[Altera_Forum]

Hi, 

 I want to tristate a group of outputs based on the state of an input pin (MAX7000S).  I have found the TRI megafunction but it looks like this uses additional resources that shouldn't be necessary. I can see that the I/O control block has a tristate buffer for the I/O pin, so it would appear that I can use this for "free", i.e., without consuming additional resources. I think I need to configure the pins as BIDIR but I can't see how to access/set the global enable for the pins that I want to control.  Can someone tell me where to find this in Quartus please? Where do I configure the output enables? Can I set the global enables on a bdf, or do I need to use VHDL to code the control action?  regards Dave

[Altera_Forum]

I don't see any of the problems you are considering.  

 You want use schematic entry, O.K. You'll either place alt_io_buf (for bidirectional pins) or alt_out_buf or tri symbols (tristate output only) and connect the tristate inputs to the respective enable signal.   Did you observe any problems when doing so? If yes, what is it?

[Altera_Forum]

Hi FvM, 

 thanks very much for the reply - when I went back to this, I saw that I had made an error, things work just as you describe !  regards Dave

[Altera_Forum]

--- Quote Start ---  You want use schematic entry, O.K. You'll either place alt_io_buf (for bidirectional pins) or alt_out_buf or tri symbols (tristate output only) and connect the tristate inputs to the respective enable signal.   --- Quote End ---    OK, so far so good. But what does the output of the TRI symbol connect to? How do I get a pin name pin name/number assigned to the TRI output?  Thanks.  ak

[Altera_Forum]

Answering my own question because Altera tech support does not exist. To create a tri-state output pin, connect the output of a TRI or TRI-BUF library part directly to the input of an output pin library part. The compiler will interpret this to mean you want a tri-state pin. The TRI control input is non-inverting - a high on the control enables the device output pin. A low on the control input puts the device pin in tri-state. 

 ak