Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Xilinx synthesis & CLOCK signals

Status
Not open for further replies.

Mirzaaur

Member level 2
Joined
Aug 5, 2005
Messages
50
Helped
3
Reputation
6
Reaction score
0
Trophy points
1,286
Activity points
1,690
hi all;

in my design I generate local clock using DCM and provide a clock on output of the virtexII.

when i try to create timing constraints after synthesis using constraints editor, I don't get the clock signals there. but some other signal which are not clock they are listed as clock. I checked these signals are detected for the transition at any level.


HOW I CAN TELL XST - SYNTHESIZER NOT TO USE CERTAIN SIGNALS AS CLOCK?

thankful for any hint or tip.

mirza
 

vintujose

Newbie level 4
Joined
Mar 26, 2008
Messages
6
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,281
Activity points
1,319
Hi instead of using the constraint editor try to have an constraint file if you check the xilinx website on topic of constraints you will find that there are certain command formats to be followed in the constraint file such that you force the file to behave in the way you want it .

hope this helps
 

cherjier

Member level 5
Joined
Dec 6, 2006
Messages
84
Helped
6
Reputation
12
Reaction score
1
Trophy points
1,288
Activity points
1,909
i give you an example:
for the input clock "clkin" to the DCM and generate 2 clocks "clkfx" and "clkdv" shown in the diagram below

54_1207215887.jpg


the constraints that you need to specified only the input clock whereas the XST will generate the clock constraints for clkfx and clkdv which you can find on the XST report.

here the example clock contraints:
NET "clkin" TNM_NET = "clkin";
TIMESPEC "TS_clkin" = PERIOD "clkin" 100.000 ns HIGH 50.00%;
 

Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Top