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Altera_Forum's avatar
Altera_Forum
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7 years ago

Auto Pin Assignment Cause CPLD cant be detected by Jtag

Hi

i have a design that is working and jtag is able to scan cpld. However, pin assignment is removed accidentally and it is auto assigned by quartus. After the design with pin auto assigned is programmed, it is no longer cant be detected by jtag. So, is there any way to recover it? Pls advice.

Thanks

1 Reply

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

    Which CPLD are you referring to?

    Check the pinout that Quartus has chosen for the device - look in the appropriate report file generated. Some CPLDs allow the JTAG pins to be used for user I/O. Check which pins are used for JTAG and whether any have been used for any of the design's I/O.

    If it has been used then I don't believe there is anything you can do but change the device.

    Quartus shouldn't use the JTAG pins for user I/O without this option being specifically selected via the Device Assignments. Once you do recover to a new part, ensure the Device Assignments do not allow Quartus to use the JTAG pins for user I/O pin.

    Cheers,

    Alex