RE: [oc] bidirection pin on acex 1k30 from Altera

["Olson, Gary" <GOlson@armillaire.com>]

Hi,
try tying gpioport_out to an input pin on a different component. ALSO
remove statement from process (TRI STate process).  ==> currentinput <=
gpioport_in;


I think the IO pin should be like this

                 gpiodirection
                ----------------
                                |                  
                            ____|__________
                            |             | 
             gpioport_out   |   TRI State |
  IO Pin  <==>-------|------|    Process  |--------<<---------Current_OUTPUT
                     |      |             |
                     |      |_____________|
                     |
                     |      |-------------|
                     |______|             |                 Current_Input
                            |IN        OUT|---------->>------------
                            |    input    |
                            |     process |
                            _______EN______
                                   |                  second component or
process on bottom
                      -------------|
                      gpiodirection

                              No tristate in lower process


thanks,
Gary Olson





-----Original Message-----
From: Daniel Haensse [mailto:daniel.haensse@alumni.ethz.ch]
Sent: Wednesday, July 25, 2001 10:40 AM
To: cores@opencores.org
Cc: cores@opencores.org
Subject: [oc] bidirection pin on acex 1k30 from Altera


Hi folks,

how can I implement a bidirectional port in vhdl. I try a inout declaration
of
the ioports. When the ports should be used as an input I use
gpioport <= 'z';

using a ACEX 1k30 altera device I get an error that the compiler can't put
the
pin into tristate.
Do I have to declare the same pin as input as well as output, just using
names
like
in a process:
...
if gpiodirection='1' then
	gpioport_out <= 'z';
else
	gpioport_out<=currentoutput;
end if;
currentinput <=gpioport_in;
...

Does anybody has a simple example

thank you 

Dani
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