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.

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

> "Naimesh" <naimesh.thakkar@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.

"Naimesh" <naimesh.thakkar@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, acher@in.tum.de
         http://wwwbode.in.tum.de/~acher
         "Oh no, not again !" The bowl of petunias

"Naimesh" <naimesh.thakkar@gmail.com> wrote in message
news:1099884025.786270.61150@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

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