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Altera_Forum
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17 years ago

Stratix III wierd JTAG Config problem

I've got 2 Stratix III devices in a JTAG chain.

If I power the board, I can scan the chain OK and program repeatedly but as soon as I switch off the power and re-apply, JTAG no longer works. i.e. I cannot even scan the chain.

If I leave the board for about an hour or thereabouts, it's OK again.

It doesn't look like it is temperature related because the board only has to be power up briefly for this fault to occur.

Any ideas where to look? I've examined the circuitry pretty thoroughly and cannot see a wiring or missing pull-up/down anywhere.

Regards,

Dave.

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  • Altera_Forum's avatar
    Altera_Forum
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    16 years ago

    i have the same problem on 3 prototype StratixIII boards. We use EP3SL340F1517C3N on own-designed board.

    When VCCPGM is below 3.27V the JTAG chain is not detected.

    When VCCPGM is over 3.28V, upto 3.75V, the JTAG communication and EPCS programming works fine!

    Please let me know if you can reproduce this. I am busy with Altera Support issue to get this resolved, but we are not making much progress here.