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Altera_Forum
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13 years ago

Series termination in Cyclone 4

I’m trying for the first time to use the on-chip termination features on a cyclone 4. I created an iobuf megafunction, enabled the series termination control, and tried to compile it. The compiler gave me this error:

Error (15857): Input port SERIESTERMINATIONCONTROL of I/O output buffer "ft2232:U_ft2232|bidir8:U_bidir8|bidir8_iobuf_bidir_2ls:bidir8_iobuf_bidir_2ls_component|obufa_0" must be connected to a termination block File: C:/Trunk/fpga_blocks/ft2232/bidir8.v Line: 69

For now, I just have the series termination control hooked to Vcc. I did have it connected to ground, and that didn’t work either. I assume that it needs some type of numeric input to select which resistance is in series with the output.

However, the output of the synthesis seems to be telling me that it wants a termination block connected on this port. I looked on the datasheet for the iobuf:

[Can't post links, google "ug_altiobuf.pdf"]

and it said that the ALTOCT is only for Stratix devices (I couldn’t select the megafunction when I had the cyclone device selected in the plug-in wizard). I think this is the dynamic termination for IO devices to conserve power… I don’t need that. I want to just select 50 or 75 ohms and be done with it. What is the synthesizer expecting me to hook into the ser_term_ctrl input, since I can’t put down an ALTOCT?

1 Reply

  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    13 years ago

    The series termination control is for user mode calibration, that's not a Cyclone IV feature. To use calibrated or non-calibrated series OCT, you just need to make output termination assignments to the pins. If you select series 50 ohm with calibration (or 25 ohm), Quartus II will enable the Rup and Rdn pins automatically when you compile.

    You don't need to use the ALTIOBUF megafunction in this case.