EmbDev.net

Forum: FPGA, VHDL & Verilog how to calculate delay.pls help


Author: Dileep L. (dileep_l)
Posted on:
Attached files:

Rate this post
0 useful
not useful
how to calculate the delay in both the cases???

synthesis report shows the same value in both the cases!!!!!!!!!!!!!!

i have attached the synthesis reports of two circuits............

Author: P. K. (pek)
Posted on:

Rate this post
0 useful
not useful
Maybe it's because your critical path has the same length in both cases 
(i.e. the additional block doesn't matter). So you have to display not 
only your longest path, but all of them.

Further more you have to consider that the synthesizer is optimizing 
your design. The three (here undescribed, but probably very simple) 
units all fit into one LUT, resulting in the same worst case path. So 
the chance is good that even the other (not yet displayed) paths have 
the same or similar length...

Author: Lothar Miller (lkmiller) (Moderator)
Posted on:

Rate this post
0 useful
not useful
Dileep L. wrote:
> how to calculate the delay in both the cases???
You have nothing to calculate, just read the value: 7,269ns. Thats it.

This consists of 5 values:
pad(in) --- routing --- LUT --- routing --- pad(out)
769ps       828ps       418ps   828ps       4.426ns

> synthesis report shows the same value in both the cases!!!!!!!!!!!!!!
The synthesis report does for sure not show any timings at all.
Timing is generated after place&route. And the timing report shows, 
that the same hardware is generated in both cases.



BTW: pls chek the following keys on your keyboard: ? ! .
They obviously tend to stuck...  :-/

Reply

Entering an e-mail address is optional. If you want to receive reply notifications by e-mail, please log in.

Rules — please read before posting

  • Post long source code as attachment, not in the text
  • Posting advertisements is forbidden.

Formatting options

  • [c]C code[/c]
  • [avrasm]AVR assembler code[/avrasm]
  • [vhdl]VHDL code[/vhdl]
  • [code]code in other languages, ASCII drawings[/code]
  • [math]formula (LaTeX syntax)[/math]




Bild automatisch verkleinern, falls nötig
Note: the original post is older than 6 months. Please don't ask any new questions in this thread, but start a new one.