UPGRADE YOUR BROWSER

We have detected your current browser version is not the latest one. Xilinx.com uses the latest web technologies to bring you the best online experience possible. Please upgrade to a Xilinx.com supported browser:Chrome, Firefox, Internet Explorer 11, Safari. Thank you!

cancel
Showing results for 
Search instead for 
Did you mean: 
Teacher rcingham
Teacher
6,212 Views
Registered: ‎09-09-2010

Clocking wizard not user-helpful

Jump to solution

Even after having read DS622, the Clocking Wizard (12.1, using ISE12.3) is not very helpful. By a process of trial-and-error I eventually persuaded it to provide me with a 200MHz to 64MHz PLL_ADV-based module.


Why can't it take in Input Frequency and Output Frequency and either give me the right answer, or tell me why it can't, and give me the nearest? I recall the A****a equivalent tool doing pretty much just that.

 

As wizards go, it's at "first year at Hogwarts" level. Grrrrr!


 


------------------------------------------
"If it don't work in simulation, it won't work on the board."
0 Kudos
1 Solution

Accepted Solutions
Xilinx Employee
Xilinx Employee
7,163 Views
Registered: ‎11-28-2007

Re: Clocking wizard not user-helpful

Jump to solution

The good news is that the new clocking wizard for Virtex6/Spartan6 and newer (7 series) works exactly the way as you suggested: you enter the input frequency and desired output frequencies and phases the wizard will take care of the rest.

 


@rcingham wrote:

Why can't it take in Input Frequency and Output Frequency and either give me the right answer, or tell me why it can't, and give me the nearest? I recall the A****a equivalent tool doing pretty much just that.

 

 


 

Cheers,
Jim
0 Kudos
4 Replies
Scholar austin
Scholar
6,206 Views
Registered: ‎02-27-2008

Re: Clocking wizard not user-helpful

Jump to solution

r,

 

I can't really answer you regarding why we don't do some things (others do).


But I can comment on philosophy:  Xilinx presumes you are going to design something that will get sold in some useful quantity (or else why are we in business?).  As such, we don't expect every user to be a seasoned genius, but we do expect them to be good at design, and good with the tools, and great at what they are doing (making their special system, box, board).

 

It is one thing to be easy to use, and push a button and get an answer, but does that sell the devices?  Being the easiest and simplest to use may also mean you can't go the fastest, or can't use the least expensive (smallest) part, and so on.

 

As the leader in the business, it is sufficient for the competition to highlight any area where they are "better" and make a big deal out of it.  This is the "top of the hill" syndrome:  everyone, and anyone is ready to knock you off.

 

In previous versions, the wizard provided the nearest frequency that it could to the requested one.  Unfortunately, there were some who didn't notice that the actual desired value wasn't there (just the nearest number that was possible by the M and D ranges) which led to support issues later (when they get expensive to address).  So, it is a "damned if you do, damned if you don't" situation.  Forcing people to intentionally make the right decisions has a lot to be said for it.  More chips get sold, and work, sooner, which is a better business model (can't argue with success).

 

Austin Lesea
Principal Engineer
Xilinx San Jose
0 Kudos
Xilinx Employee
Xilinx Employee
7,164 Views
Registered: ‎11-28-2007

Re: Clocking wizard not user-helpful

Jump to solution

The good news is that the new clocking wizard for Virtex6/Spartan6 and newer (7 series) works exactly the way as you suggested: you enter the input frequency and desired output frequencies and phases the wizard will take care of the rest.

 


@rcingham wrote:

Why can't it take in Input Frequency and Output Frequency and either give me the right answer, or tell me why it can't, and give me the nearest? I recall the A****a equivalent tool doing pretty much just that.

 

 


 

Cheers,
Jim
0 Kudos
Teacher rcingham
Teacher
6,128 Views
Registered: ‎09-09-2010

Re: Clocking wizard not user-helpful

Jump to solution
Why has this been moved to the 'Silicon Devices - Others' forum, when it is clearly about an IP tool?

------------------------------------------
"If it don't work in simulation, it won't work on the board."
0 Kudos
Xilinx Employee
Xilinx Employee
6,078 Views
Registered: ‎03-23-2010

Re: Clocking wizard not user-helpful

Jump to solution

It's because the clocking wizard is actually tied to the MMCMs/DCMs/PLLs, so it is tied more to the silicon itself.

0 Kudos