Velocity Reviews - Computer Hardware Reviews

Velocity Reviews > Newsgroups > Programming > VHDL > IBUFG and BUFG +xilinx

Reply
Thread Tools

IBUFG and BUFG +xilinx

 
 
williams
Guest
Posts: n/a
 
      04-04-2005
Hello Guys,
I had a doubt about the IBUFG and BUFG in xilinx.
1.I have connected clock from oscillator to CLKG IO of the Xilinx. In
this case is it required to instantiate the IBUFG inside my code
also?.
2. The DCM output is already BUFG i think and so is it required to
BUFG again in my code?

Thanks and regards
Williams
 
Reply With Quote
 
 
 
 
Marc Randolph
Guest
Posts: n/a
 
      04-04-2005

williams wrote:
> Hello Guys,
> I had a doubt about the IBUFG and BUFG in xilinx.
> 1.I have connected clock from oscillator to CLKG IO of the Xilinx. In
> this case is it required to instantiate the IBUFG inside my code
> also?.


Howdy Williams,

I believe the tools will usually do it for you - the exception that
comes to mind is differential clocks.

> 2. The DCM output is already BUFG i think and so is it required to
> BUFG again in my code?


BUFG is another name for a global buffer. Although most of the time
you'd want it on a global buffer, the output of a DCM is not "already
BUFG", nor would you always want it to be. Even if it does automaticly
insert a BUFG in some situations, I rarely trust that it will every
time.

Have fun,

Marc

 
Reply With Quote
 
 
 
 
Vladislav Muravin
Guest
Posts: n/a
 
      04-05-2005
Williams,

By default, an IBUFG & BUFG are instantiated, but if you specify something
like:

wire dcmclkout;
// synthesis attribute clock_signal of dcmclkout is true
// synthesis attribute clock_buffer of dcmclkout is none

the synthesis tool will not issue a clock buffer placement.

i usually instantiate IBUFG & BUFG, for safety.
hope this helps.

Vladislav

"williams" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed) om...
> Hello Guys,
> I had a doubt about the IBUFG and BUFG in xilinx.
> 1.I have connected clock from oscillator to CLKG IO of the Xilinx. In
> this case is it required to instantiate the IBUFG inside my code
> also?.
> 2. The DCM output is already BUFG i think and so is it required to
> BUFG again in my code?
>
> Thanks and regards
> Williams



 
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
if and and vs if and,and titi VHDL 4 03-11-2007 05:23 AM



Advertisments