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Comp.Arch.FPGA | XST Question

There are 5 messages in this thread.

You are currently looking at messages 0 to 5.

XST Question - Naimesh - 2004-11-07 22:20:00

How do I buffer a signal in XST as I feel it is
getting overloaded.
if I write
Signal1 <= Signal;
XST automatically optimizes it.

Please help.
Naimesh



Re: XST Question - Antti Lukats - 2004-11-08 03:25:00

"Naimesh" <n...@gmail.com> wrote in message
news:1...@f14g2000cwb.googlegroups.com...
> How do I buffer a signal in XST as I feel it is getting overloaded.
> if I write
> Signal1 <= Signal;
> XST automatically optimizes it.

if the signal is a clock signal you can instantiate a BUFG or multiple BUFGs
to optain load manual load balancing

Antti

Re: XST Question - Georg Acher - 2004-11-08 07:02:00

"Naimesh"
<n...@gmail.com> writes:
>How do I buffer a signal in XST as I feel it is getting overloaded.
>if I write
>Signal1 <= Signal;
>XST automatically optimizes it.

You can add "-max_fanout 50" (or whatever fanout you want) to the
.xst-configfile
or edit the appropriate GUI-form.... That setting is global, but it should be
possible to pass it as an signal attribute.

-- 
         Georg Acher, a...@in.tum.de
         http://wwwbode.in.tum.de/~acher
         "Oh no, not again !" The bowl of petunias

Re: XST Question - General Schvantzkoph - 2004-11-08 10:52:00

On Mon, 08 Nov 2004 12:02:41 +0000, Georg Acher
wrote:

> "Naimesh" <n...@gmail.com> writes:
>>How do I buffer a signal in XST as I feel it is getting overloaded.
>>if I write
>>Signal1 <= Signal;
>>XST automatically optimizes it.
> 
> You can add "-max_fanout 50" (or whatever fanout you want) to the
.xst-configfile
> or edit the appropriate GUI-form.... That setting is global, but it should be
> possible to pass it as an signal attribute.

Look at the constraints guide, you can set max fanout for a specific
signal or you can do it globally.

Re: XST Question - Sriraman - 2004-12-25 00:12:00

We are using a 20 input (each 8 bit wide) coregen
instantiated MUX operating at 160 MHz on a Vitex-E device. When placed and routed in
ISE6.2i, we get that the timing-error that the mux select lines are having fanout problem.
We tried duplicating the net source, but still the problem persists. Any Help please.