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Altera_Forum's avatar
Altera_Forum
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12 years ago

CONF_DONE as input?

Hello, sorry if this has been asked already.

Specifically for Cyclone V: so CONF_DONE is a bidirectional pin. Its function as input is not very clear or not very well documented or maybe I missed the important part. Perhaps it is called bidirectional because its state can be sampled thru JTAG? Any other internal function as an input? One note from Spansion might suggest the Low to High transition of CONF_DONE is used to begin initialization, is this true? I was not able to find this in an Altera document.

Reason I am asking is, I'd like to be able to delay entering user mode, after configuration has finished, and I wonder if I could do that by holding CONF_DONE low.

Thanks

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

    CONF_DONE is an input when multiple FPGAs are configured sequentially; as each FPGA configures they release their CONF_DONE driver (which was driving low) and then wait for the CONF_DONE signal to go high before entering user mode. This ensures that all FPGAs enter user-mode once configuration of all devices is done.

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    I'd like to be able to delay entering user mode, after configuration has finished, and I wonder if I could do that by holding CONF_DONE low

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    Yes, this is ok, and used to be stated in some of the device handbooks.

    Cheers,

    Dave