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Altera_Forum's avatar
Altera_Forum
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10 years ago

Transceiver Toolkit - "locked" indicators

I'm looking for some further explanation of the LOCKED indicators in TTK.

Currently I use version 15.0 build 153 of System Console.

My questions are:

--> Is it normal for the Rx LOCKED indicators to blink green and then yellow with a properly functioning link? If so, what is this indicating? Does the TTK only say "LOCKED" when data is coming across the link, and then goes unlocked after?

I have a loopback cable that connects Tx to Rx on 4 channels. Whether or not the cable is actually connected, I see "LOCKED to ref" and "LOCKED to data" fluctuate between green and yellow within TTK. My initial interpretation was that "LOCKED to ref" would only turn green when I plugged my loopback connector in...and would stay green until the cable was disconnected. However, since TTK is saying "LOCKED to ref" without any cable on the interface, I'm a bit confused. The toggling of LOCKED also occurs whether or not I'm running something with TTK.

I put SignalTap on the "lockedtoref" and "lockedtodata" signals from the XCVR and those are also toggling unexpectedly; therefore I think it's not just the TTK GUI being flakey.

3 Replies

  • Altera_Forum's avatar
    Altera_Forum
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    10 years ago

    With a properly functioning link you should never loose lock to data. With a reasonable channel you could see occasional data errors, how often is an indication of the quality of the channel and the RX/TX eq settings, but not lock to data dropping out.

    When locked to data is set the locked to ref is a dont care. It is possible to spuriously report lock to data briefly due to picking up noise if the inputs are floating or at a signal that is not at the correct frequency. If you have a good steady state signal on the data and lock to ref is still fluctuating then your refclk is not high quality and all bets are off.
  • Altera_Forum's avatar
    Altera_Forum
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    10 years ago

    Thanks Necare.

    A further bit of clarification: I have used this link successfully to send 10GbE prior to this. So I know the link works...to some degree. I could certainly have an issue with how I've configured the PHY different from the 10GbE core I used though.

    The other interesting datapoints are that BER is very bad, somewhere around 1e-2. However, the TTK Eye diagram looks OK. (I'm not an expert in what it's supposed to look like. There's an opening with ratio 40/20 if I recall correctly.)

    At this point, I'm just trying to find some solid indicator of the link status, either OK or BAD.
  • Altera_Forum's avatar
    Altera_Forum
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    10 years ago

    The issue ended up being that the "pll locked" signal from my ATX PLL had been unhooked from the Reset Controller IP in Qsys. Therefore, I think the Reset Controller was constantly trying to reset things.

    Now, when I open TTK, it shows a solid "locked to data" when I am running any test. (i.e. after hitting "Start")