Velocity Reviews - Computer Hardware Reviews

Velocity Reviews > Newsgroups > Programming > VHDL > bidirectional connection between two bidirectional ports

Reply
Thread Tools

bidirectional connection between two bidirectional ports

 
 
KJ
Guest
Posts: n/a
 
      09-05-2006

"Manfred Balik" <(E-Mail Removed)> wrote in message
news:44fd3402$0$11094$(E-Mail Removed) ...
>I changed my design to (like Antti suggested):
> port1 <= port2 when (port1_output_enable = '1') else 'Z';
> port2 <= port1 when (port2_output_enable = '1') else 'Z';
> but this doesn't work in Altera Quartus Simulation ((
> the output at port1 and port2 shows "Z" when enabled and otherwise
> "Unknown"
> Is this just an malfunction of Quartus Simulation???? and will it work in
> real hardware (Altera MAX3000A)???


Depends completely on what your model for port1 and port2 are doing. Do you
have some form of VHDL model for the external 'things' that are driving
port1 and port2? Are you trying to 'force' them? If forcing, how?

Since port1 and port2 are I/O pins on your design, then when things are just
'sitting there' (i.e. port1_output_enable and port2_output_enable are both
'0') then port1 and port2 will be sitting there at 'Z'. When
port1_output_enable goes to a '1', your design should start driving port1
(i.e. now it's an output) with whatever is on port2 (which is now an input).
So, ask yourself, at that time, what is driving port2? The answer is that
it is your simulation testbench, port2 needs to be driven, at that time,
just like any other input to your design. Once you've got that understood,
you'll need to answer the same questions about port1 when your signal
'port2_output_enable' is active.

KJ


 
Reply With Quote
 
 
 
 
Manfred Balik
Guest
Posts: n/a
 
      09-05-2006
Tanks for your answers ...
Now it works - it was just a handling error of the Quartus Simulator by me
(embarrassing)
Manfred


"KJ" <(E-Mail Removed)> schrieb im Newsbeitrag
news:O6cLg.15443$%(E-Mail Removed) et...
>
> "Manfred Balik" <(E-Mail Removed)> wrote in message
> news:44fd3402$0$11094$(E-Mail Removed) ...
>>I changed my design to (like Antti suggested):
>> port1 <= port2 when (port1_output_enable = '1') else 'Z';
>> port2 <= port1 when (port2_output_enable = '1') else 'Z';
>> but this doesn't work in Altera Quartus Simulation ((
>> the output at port1 and port2 shows "Z" when enabled and otherwise
>> "Unknown"
>> Is this just an malfunction of Quartus Simulation???? and will it work in
>> real hardware (Altera MAX3000A)???

>
> Depends completely on what your model for port1 and port2 are doing. Do
> you have some form of VHDL model for the external 'things' that are
> driving port1 and port2? Are you trying to 'force' them? If forcing,
> how?
>
> Since port1 and port2 are I/O pins on your design, then when things are
> just 'sitting there' (i.e. port1_output_enable and port2_output_enable are
> both '0') then port1 and port2 will be sitting there at 'Z'. When
> port1_output_enable goes to a '1', your design should start driving port1
> (i.e. now it's an output) with whatever is on port2 (which is now an
> input). So, ask yourself, at that time, what is driving port2? The answer
> is that it is your simulation testbench, port2 needs to be driven, at that
> time, just like any other input to your design. Once you've got that
> understood, you'll need to answer the same questions about port1 when your
> signal 'port2_output_enable' is active.
>
> KJ
>



 
Reply With Quote
 
 
 
 
Marc Guardiani
Guest
Posts: n/a
 
      09-10-2006
Manfred Balik wrote:
> Hello,
> I am using an Altera MAX3000A CPLD to make level conversion from 5V-TTL to
> 3.3V-TTL (and further jobs...).
> My problem is - I can't connect two bidirectional ports directly to get a
> bidirectional connection.
> I'm using Altera Quartus II, a direct connection produces an error message
> and a simple VHDL-block doesn't solve the problem, too.
> my VHDL-code is like:
> ENTITY ...
> port1 : INOUT STD_LOGIC;
> port2 : INOUT STD_LOGIC;
> ARCHITECTURE...
> port1 <= port2;
> port2 <= port1;
>
> How can I make a bidirectional connection between two bidirectional ports???
> thanks, Manfred


Take a look at Analog Devices line of level translators -
http://www.analog.com/en/subCat/0,28...0%255F,00.html
The ADG3301/04/08 will connect 1/4/8-bit bidirectional buses together
with 3-state control.

Marc

 
Reply With Quote
 
 
 
Reply

Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Type of actual ports is not compatible with type of ports of entity. mreister VHDL 1 05-25-2010 11:30 AM
Connection problem between the ports saku.loukonen@gmail.com Cisco 1 03-15-2009 11:57 AM
Connecting two bidirectional ports together VJN VHDL 0 06-06-2007 03:22 PM
Recommendations Please for a PCI card w/ two USB 2 Ports and FireWaire Ports Mike Digital Photography 27 02-26-2006 12:54 AM
Activate a VPN IPSec between 2 PIX without generate a bidirectional flow at start... Laurent Lepage Cisco 0 03-03-2004 04:31 PM



Advertisments