Triming timing constraints from pin ...

Mon Feb 22, 2010 2:37 pm   

Hi all,

I'm working on a Virtex5 xc5vlx50 and in my design I need to use some
block ram. I generated the core with core generator, but when I
implement the design I got this warning during mapping:


WARNING:Pack:231 - trimming timing constraints from pin hit2/RAM1/BU2/
U0/blk_mem_generator/valid.cstr/ramloop[0].ram.r/v5_init.ram/TR
UE_DP.SINGLE_PRIM36.TDP of frag REGCLKBL connected to power/ground net
hit2/RAM1/BU2/U0/blk_mem_generator/valid.cstr/ramloop[0].ram.r/
v5_init.ram/TR UE_DP.SINGLE_PRIM36.TDP_REGCLKBL_tiesig

Does anyone knows what it mean and how can i fix it? I found nothing
neither on the xilinx site nor on the web

Thanks all

Bye

Dek

Mon Feb 22, 2010 6:45 pm   

Dek,

It is a warning: you do not necessarily have to fix it.

The tools are telling you that a net to a constant (1=power, or
0=ground) had its timing constraint removed (ignored).

That is a perfectly OK thing to do.

It is up to you to read each warning, and check out what it means.

This one is easy, let it go.

Austin

Tue Feb 23, 2010 5:20 pm   

On 22 Feb, 16:45, austin <aus...@xilinx.com> wrote:

Hi Austin

Thanks for the reply; the point is that I have a project that uses
some block ram; In functional simulation everything works fine, when I
do synthesys and place and route I got no errors, no timing related
problems, and just 2 kind of warnings:

Xst:2211: ... line 130: Instantiating black box module <ram_128>
( see http://groups.google.it/group/comp.lang.vhdl/browse_thread/thread/cf702b52f28c2674/702ad29181e18171#702ad29181e18171
)

and

Pack:231 - trimming timing constraints from pin as described above

If I try to do a post layout simulation of this design with Modelsim;
I got this warning:

# ** Warning: /X_FF HOLD Low VIOLATION ON I WITH RESPECT TO CLK;
# Expected := 0.195 ns; Observed := 0.006 ns; At : 191.527 ns
# Time: 191527 ps Iteration: 1 Instance: /newdaedalus_tb/top/
control_cnt_0

and the design does not behave like in functional analysis. I also
implemented the bitfile on real hardware but it doesn't work. That's
why I was asking about that warning, because I really can't get where
the problem could be...

I'm using the block ram @ 40 MHz, but it shouldn't be a problem,
right?

Thanks

Bye

Dek