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All flip-flops inside FPGA are D flip flop?

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EDA_hg81

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convert dff to jkff

Thanks
 

jk-ff design dff

AFAIK they all are D FF/Latches in Xilinx devices. Never used Altera though, probably the same because they are the most commonly used for both sequential logic and storage registers. If other types are needed they can be manifested with the help of surrounding logic.
 

    EDA_hg81

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xilinx ffs to ffs period constraints

If they are all D Flip flops inside FPGA, according to the timing digram of D flip flops as followings:

We do not need pay too much attentions on internal time delay between pipelined registers inside FPGA since the data are going to be captured any way if we arrange registers inside FPGA properly.

Do you think I am right?
 

fpga dff

Some Xilinx FPGAs also provide special dual data rate (DDR) flops in the IOBs. They have two clocks.

If your design is synchronous and uses only one clock, then maybe all you need is a clock PERIOD constraint. Then your software will automatically place and route the logic to satisfy the setup and hold requirements of all the flops (or it may complain that it can't meet your constraints). For more complex designs and for critical I/O timing, you may need additional timing constraints.

Your timing diagram shows DATA changing simultaneously with CLK. Beware of possible setup/hold violations.
 

    EDA_hg81

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ddr flop clocks xilinx

The short answer to your question in regards to Xilinx FPGAs is yes the FF in FPGAs are DFF. HOWEVER you cannot always just ignore the timing element related to these devices.

A good example is the difference between the Spartan 2 familiy and the Virtex 5. Both are FPGAs and both have FFs but you must look at the basic element of these devices. The slice as its called at Xilinx is different between these to familys and will have different timing for the same piece of code.

You must always be cognizant of your timing to FFs whether D type or not. Just look at the slices of the two familys I mentioned above to see what type of logic proceeds these. If that does not show you that you still must pay attention to FF timing whether you are pipelining them or not then all I can say is good luck.

For reference info about what I am talking about see page 11 of the complete Spartan 2 family datasheet and pages 157, 158, & 161 of the Virtex 5 users guide.

E
 

    EDA_hg81

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fpga d flip flop

Thank you all so much.
 

ddr flip flop on fpga

hi !
U write ur own code for JK flip flop in any of the HDL. I think the FPGA will infer some combi logic and add it to DFF to convert it into JK.

correct me if i am wrong

thanks and regads

Deepak
 

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