What clock domain is a Xilinx DCM LOCK signal in?

I don't see in the Xilinx documentation in what clock domain the LOCK signal coming from a DCM is produced. Do I need to synchronize it into the CLK0 domain to avoid metastability?

Thanks!

John Providenza

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John Providenza
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You can phase align feedback using either the CLK0 or CLK2X DCM outputs.

There is a relatively new application note on DCMs in Spartan-3 that may be useful to your question.

XAPP462: Using Digital Clock Managers (DCMs) in Spartan-3 FPGAs

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Phase alignment is optional for the Digital Frequency Synthesizer function in a DCM.

--------------------------------- Steven K. Knapp Applications Manager, Xilinx Inc. Spartan-3/II/IIE FPGAs

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--------------------------------- Spartan-3: Make it Your ASIC

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Steven K. Knapp

I understand about the phase align capabilities provided by the DCM, but what clock domain are the LOCKED and STATUS bits created in?

I want to feed LOCKED into a state machine, but I don't see in the Xilinx docs anyplace which clock produces it.

John Providenza

Reply to
John Providenza

Everything, except the RESET input, is controlled by the rising edge of CLKIN.

--------------------------------- Steven K. Knapp Applications Manager, Xilinx Inc. Spartan-3/II/IIE FPGAs

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--------------------------------- Spartan-3: Make it Your ASIC

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Steven K. Knapp

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