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Altera_Forum's avatar
Altera_Forum
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17 years ago

PCI Clamp Diode

Hi,

Does anyone know how to disable the PCI clamp diode for individual Inputs on a Flex10KE within Quartus ?. I have the I/O configured for LVTTL but the inputs are being clamped by the clamp diode.

Thanks

Graham

2 Replies

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

    The FLEX 10KE manual tells different:

    --- Quote Start ---

    The PCI pull-up clamping diode, slew-rate control, and open-drain output options

    are controlled pin-by-pin via Altera software logic options.

    --- Quote End ---

    The actual configuration can be reviewed in the fitter resource section anyway, PCI clamp diodes should be controllable via Pin Planner or Assignment Editor as for any FPGA family.
  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    17 years ago

    I haven't tested it for the FLEX family, but usually you set 'PCI IO' assignment with value 'off' to disable the clamping diode.