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DS110DF410EVK "Hello World" Loopback

John Gaida
Prodigy 80 points
Other Parts Discussed in Thread: DS110DF410EVK, DS110DF410

I am considering the DS110DF410 for a passive cable application and I am trying to use the DS110DF410EVK to test cables, speed, and distance. I have been connecting the cable to theSMA's of a transmitter to the SMA's of a receiver and configuring the transmitter to output the VCO-Q, or 10MHZ, or raw data with free run VCO.  I get a signal detected on the recieve channel, but fail to get a CDR lock. I am looking for a simple hello world loopback setup on the EVK, what am I doing wrong or how can I achieve?

Thanks

  • 0
    TI__Mastermind 29655 points

    Hi John,

    Thanks for posting, and my apologies for the delayed response.

    CDR lock can only occur when the VCO detects incoming signal running at a pre-determined data-rate. If your incoming signal does not match the pre-determined data-rate or sub-rate, the PLL will not lock. Setting the acceptable rates/sub-rates necessary to achieve lock with the incoming signal is accomplished either automatically in standards-based mode or manually via PPM count override (see p. 12-13 of the DS110DF410 datasheet). Assuming you are running with the default setup of "Standards-Based Mode", Reg 0x2F will reveal which data rates the retimer is testing for lock.

    Since Reg 0x2F is 0x04 by default, the CDR is anticipating an incoming frequency of either 10.3125G, 10G, or 1.25G. If you are not using any one of these rates, then I suspect that may be the reason the CDR is not locking.

    Thanks,

    Michael