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Altera_Forum's avatar
Altera_Forum
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8 years ago

CPLD(EPM1270-F256) I/O Status

I'm using EPM1270-F256(ALTERA MAX II CPLD) in Ultrasound system control pannel

K6 of I/O port is used input port.

That is connecting with switch and PC power signal.

That i meane checking switch action.

I knew that I/O port is floating in normal status.

But, I had seen that port short with internal GND in CPLD.

So, I would like to how I/O port can that status.

What case cause that status(short with GND?

3 Replies

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

    In the project settings you can set all unused I/O to connect to GND. That may be the case.

    If so, it will be fine to use this pin for a new input signal.

    Cheers,

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

    Thank you for reply.

    I had defined K6 port used pin and be input.

    That means K6 is floating status.

    But it changed status that short with GND.

    So, my question is what case cause to change I/O status.

    Regards,

    Son.
  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    8 years ago

    Do you actually use the signal, that goes in on pin K6, in your design? Even if you specify that it's an input at your top level, unless it's used for something it will be treated as unused.

    Cheers,

    Alex