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Ad13's avatar
Ad13
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4 years ago

JTAG - CLK Pin limited to 0.7V

I have 2 x custom boards with 10CX085YU484E6G and a MT25QU01GB flash device that have been working fine. However, for some reason Quartus changed the device and when I last programmed the FPGA and Flash with the wrong image I can now no longer see the device on JTAG. It cannot detect anything on the JTAG chain.

I've tried removing the MT25QU010GB device, and when I put a scope on the JTAG clock signal it is clean and square but only gets to at about 0.7V. TDI looks good, but the CLK signal appears clamped.

Could I have damaged the JTAG CLK inputs somehow?

I've done exactly the same thing on both boards with now get identical behaviour.

Any help appreciated.

8 Replies

  • Ad13's avatar
    Ad13
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    4 years ago

    Hello Aiman,

    Thanks for your input.

    While the certificate had indeed expired, fixing that issue did not solve my problem. This is verified on 3 different PCs with multiple JTAG cables (USB Blaster 1 and 2).

    Interestingly on one setup doing Autodetect does detect a device but with an unknown ID (UNKNOWN_2EF20DD). Screenshot attached.

    I have also noticed with USB Blaster 1 the clock gets to about 400mV, and on USB Blaster 2 the clock is about 0.7V.

    Many thanks.

    Adrian.

    • Ad13's avatar
      Ad13
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      4 years ago

      Hello Aiman,

      Thanks for your response.

      I have verified multiple times the pull-up and pull-down resistors on the JTAG lines.

      The TCK signal is clean, crisp and not in any way noisy - but just clipped at 0.7Volts. TCK is pulled low through a 1K resistor.

      I've tested with 4 cables - a mix of Altera USB Blaster 2, 1 and 3rd party tools. The actual level of the TCK signal changes depending on the cable used, with USB Blaster 2 being the best.

      Pin 4 is at 1.8V, which is the VCCIO level and VCCPGM level.

      All rails are as expected - the device exits reset as it is configured for active serial (via MSEL) and I can see it try and load an image from the flash device.

      As a test I added a 10K pull up resistor to TCK with no download cable attached, and similarly it only goes to 0.7V.

      Must be a damaged input? How can I have done this by programming with the wrong image? It really was immediate, on 2 boards, after programming with the wrong device selected. Could it have sent one of the reserved JTAG codes?

      Many thanks,

      Adrian

  • NurAiman_M_Intel's avatar
    NurAiman_M_Intel
    Icon for Super Contributor rankSuper Contributor
    4 years ago

    Hi Adrian,


    Apologize that previous answer did not solve your issue.


    • Since you mention that it work previously, is the design compiling in new Quartus? or any change when compiling the design?
    • Where did you measure the JTAG clock? is it the 10 pin header on board or the output from USB Blaster?


    Regards,

    Aiman




  • NurAiman_M_Intel's avatar
    NurAiman_M_Intel
    Icon for Super Contributor rankSuper Contributor
    4 years ago

    Hi,


    Any update for this request? I believe a request has been open in Intel Premier Support. Kindly response to the support.


    Thanks.


    Regards,

    Aiman


    • Ad13's avatar
      Ad13
      Icon for New Contributor rankNew Contributor
      4 years ago

      Dear Aiman,

      Sorry for the delay.

      I can compile and download the design to the one remaining board without issue, and have done so many times.

      I am measuring TCK actually on the PCB - PIN1 of the 10 pin header.

      The actual voltage does depend on the type of USB Blaster used - USB Blaster 2 gets to about 0.7V but others are slightly lower.

      Many thanks,

      Adrian

  • NurAiman_M_Intel's avatar
    NurAiman_M_Intel
    Icon for Super Contributor rankSuper Contributor
    4 years ago

    I’m glad that your question has been addressed, I now transition this thread to community support. If you have a new question, feel free to open a new thread to get the support from Intel experts. Otherwise, the community users will continue to help you on this thread. Thank you.