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Andy Peters
07/13/12 03:27
Read: 534 times
Tucson, Az

#187920 - re: BUFG
Responding to: Mahmood Elnasser's previous message
Mahmood Elnasser said:
Andy Peters said:

The important thing to remember is that XST is really kinda stupid, and you have to instantiate the BUFGs for all of the DCM inputs and outputs.
So, at minimum, you need a BUFG for the input clock (which drives the DCM CLKIN) and a BUFG for each output. So if you use CLK0, CLK2X and CLKFX, you need three more BUFGs. In addition, the output of the CLK0 BUFG should be used to drive the CLKFB input (and set the generic that indicates clock feedback 1X or 2X to 1X).

What is puzzling me is that these BUFGs are automatically generated by the core gen in the DCM instantiation file, do I have to repeat them in my source?

No, you don't.

Like I said, I have a "template" of sorts of a clocks entity which instantiates the DCM and all relevant BUFGs, which is similar to what the Xilinx Core Generator gives you. Except that I document it better, and the code style doesn't look like it was generated by an idiot.


List of 19 messages in thread
VHDL DCM problem      Mahmood Elnasser      07/10/12 20:09      
   coregen      Maarten Brock      07/11/12 03:04      
      Example found in tool itself!      Mahmood Elnasser      07/11/12 04:48      
         Xilinx DCM      Andy Peters      07/12/12 04:14      
            BUFG      Mahmood Elnasser      07/12/12 09:55      
               re: BUFG      Andy Peters      07/13/12 03:27      
                  Can you share it?      Mahmood Elnasser      07/13/12 04:39      
            Basically don't use coregen      Jez Smith      07/13/12 08:40      
               Altera and Xilinx , probably lattice soon      Mahmood Elnasser      07/13/12 09:27      
                  Altera joy      Jez Smith      07/14/12 08:52      
                  USB blaster clones      Dejan Durdenic      07/14/12 20:59      
   it's working!!!!      Mahmood Elnasser      07/14/12 03:46      
   this warning...      Jez Smith      07/21/12 15:39      
      I don't know      Mahmood Elnasser      07/22/12 09:57      
         new warning      Mahmood Elnasser      07/23/12 09:12      
            contraints      Andy Peters      07/24/12 14:42      
               No change to source      Mahmood Elnasser      07/24/12 23:03      
                  Timing Constraints        Justin Fontes      07/25/12 10:15      
      CoreGen FTL      Andy Peters      07/24/12 14:41      

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