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Visitor jun.won
Visitor
154 Views
Registered: ‎11-25-2019

cdrlock does not work when using 'RX CDR Lock to Reference' mode

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Hello

 

I want an RX CDR to lock to reference clock.

I set RXCDRHOLD = 1’b1 and RXCDROVRDEN = 1’b0 according to an answer record (https://www.xilinx.com/support/answers/62527.html).

 

However, 'rxcdrlock_int' and 'rx_cdr_stable_int' signals were not asserted (i.e., constant 0).

 

How could I get 'rxcdrlock_int' asserted?

In addition, could you let me know the meaning of 'rxcdrlock_int' when using RX CDR locked to reference mode?

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Moderator
Moderator
116 Views
Registered: ‎07-30-2007

Re: cdrlock does not work when using 'RX CDR Lock to Reference' mode

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The CDR is not "locked" in lock to reference mode. Refer to page 217 of UG578 v1.3.  The RXCDRHOLD disables the phase interpolator which makes the block just a pass through and turns the channel into just a division of the Q/CPLL clock's output.  As long as the Q/CPLL is locked you're good.  There is nothing else in the channel to lock in that mode.




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1 Reply
Moderator
Moderator
117 Views
Registered: ‎07-30-2007

Re: cdrlock does not work when using 'RX CDR Lock to Reference' mode

Jump to solution

The CDR is not "locked" in lock to reference mode. Refer to page 217 of UG578 v1.3.  The RXCDRHOLD disables the phase interpolator which makes the block just a pass through and turns the channel into just a division of the Q/CPLL clock's output.  As long as the Q/CPLL is locked you're good.  There is nothing else in the channel to lock in that mode.




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Don't forget to reply, kudo, and accept as solution
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View solution in original post