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Altera_Forum's avatar
Altera_Forum
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14 years ago

one shot and D flip flops

Greetings.

What is the advantage of putting one shots (one clock pulse if the D in a flip flop goes high) and basic D flip flops in designs? I see them placed in a lot of designs I look and and wonder if there are certain rules experienced designers use for them. When would be a good time to use a "Oneshot" or a "D flip flop"

Thanks

3 Replies

  • Altera_Forum's avatar
    Altera_Forum
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    using the outputs of logic/registers as clocks is a general no-no in FPGAs. You CAN do it, but unless you get the "clock" into a clock net you're going to have timing problems.

    Its best to use clock enables (and much less complicated and much easier for another engineer to understand.)
  • Altera_Forum's avatar
    Altera_Forum
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    What is then the best use for D flip flops in a design?

    thanks for the reply
  • Altera_Forum's avatar
    Altera_Forum
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    basically everything involving a clock. They create the pipeline

    D types are the basis of all designs. You can use clock enables to move data along the pipeline or not.