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Vic3Dexe's avatar
Vic3Dexe
Icon for Occasional Contributor rankOccasional Contributor
4 years ago
Solved

Cyclone III slave (PS) embedded memory errors

I have two Cyc III devices (master-slave, AS and PS respectively) + EPCS16 flash. In both devices I have ROMs (megafunction), one in the master and two of them in the slave. All ROMs are initialize...
  • Vic3Dexe's avatar
    Vic3Dexe
    3 years ago

    I think I've found the problem.

    There is a trace connected to pin 76 on the master and pin 99 on the slave. Trace is pulled up to 3.3V via 2.2k

    This **bleep** resistor was dead, and the trace was actually floating.

    I didn't use this pins before, so I can't reveal the resistor is dead.

    As I start to use it, all logic became a total mess. Something worked, something not. By elimination I found the culprit.

    I can't explain how this trace connected with loading errors (when FPGA not even in user mode), but the fact is - replacing resistor solved all problems, ROMs working now (though I don't use them anymore).

    Thanks to all, problem solved!

hareesh's avatar
hareesh
Icon for Frequent Contributor rankFrequent Contributor
4 years ago

hi @Vic3Dexe ,

scope shot from oscilloscope is required so we know what happened in the trace DATA and DCLK. can you share that

thanks,

Vic3Dexe's avatar
Vic3Dexe
Icon for Occasional Contributor rankOccasional Contributor
4 years ago

No problem as soon as someone share oscilloscope to me.

Where exactly you need traces? AS_DCLK/AS_DATA or SOUTH_DCLK/SOUTH_DATA (after buffers)?

I've cut traces and placed series resistors afters buffers (51R). Should I remove them before measurement?

  • hareesh's avatar
    hareesh
    Icon for Frequent Contributor rankFrequent Contributor
    4 years ago

    it's better to share at two points and one time measure with resistors and another time with out.

    on data line and clk line are you using 51R resistor only ?

    • Vic3Dexe's avatar
      Vic3Dexe
      Icon for Occasional Contributor rankOccasional Contributor
      4 years ago

      Well, it will take some time to find oscilloscope.

      @hareesh wrote:

      on data line and clk line are you using 51R resistor only ?

      Sorry, don't understand this question.

      • hareesh's avatar
        hareesh
        Icon for Frequent Contributor rankFrequent Contributor
        4 years ago

        @Vic3Dexe wrote: I've cut traces and placed series resistors afters buffers (51R)

        those resistors where are you connecting (data line or clk line or on both lines)

        • if you see bellow attachment in schematic on clk and data lines using two different resistors in series.
  • hareesh's avatar
    hareesh
    Icon for Frequent Contributor rankFrequent Contributor
    4 years ago

    hi @Vic3Dexe ,

    scope shot from oscilloscope is required. when can you share?

    thanks,

    • Vic3Dexe's avatar
      Vic3Dexe
      Icon for Occasional Contributor rankOccasional Contributor
      4 years ago

      Awaiting access to my friend's oscilloscope (it's in use for now). Don't know when it will be avail. Maybe this week, maybe next.

      • hareesh's avatar
        hareesh
        Icon for Frequent Contributor rankFrequent Contributor
        3 years ago

        Hi @Vic3Dexe,

        Since there are no update from you. pls respond when can you share oscilloscope data.

        Thanks,