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SHard2's avatar
SHard2
Icon for Occasional Contributor rankOccasional Contributor
5 years ago
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Cyclone V nCEO pin , what VCCIO when used as IO pin

Hi

From the documentation I am not clear what VCCIO standard the nCEO pin uses when configured as a general purpose IO pin.

For example, I have a Cyclone V where VCCIO5A and VCCIO5B are connected to 3V3 but VCCPGM is connected to 3V0.

With nCEO set to be used as a general purpose IO pin, am I safe to feed 3V3 into the nCEO pin?

Any advice is greatly appreciated.

Best regards

Simon

  • AminT_Intel's avatar
    AminT_Intel
    5 years ago

    Hello Simon,

    The operating voltage for the configuration input pin is independent of the I/O banks power supply,
    VCCIO, during configuration. You may refer on page 246 of Cyclone V Device Handbook from this link: https://www.intel.com/content/dam/www/programmable/us/en/pdfs/literature/hb/cyclone-v/cv_5v2.pdf

    The nCEO pin will comply with Table 15 from page 19 of that Cyclone V Device Datasheet when it is configured as general purpose I/O pin. Thus, the Vih value will depends on the I/O standard you set.

    You are safe to put 3.3V of Vih to nCEO if you set 3.0-V LVTTL as I/O standard as situation you previously mentioned because the value of Vih can go up to 3.6V in that particular I/O standard.

    Hope this clarifies.

7 Replies

  • AminT_Intel's avatar
    AminT_Intel
    Icon for Regular Contributor rankRegular Contributor
    5 years ago

    Hello,

    There are two uses of nCEO pin. It can be used as dual-purpose pins and regular I/O pin. During multi-device configuration, this pin feeds the nCE pin of the next device in the chain. If this pin is not feeding the nCE pin of the next device, you can use this pin as a regular I/O pin. To use it as dual purpose pins: Assignments > Device > Device and Pin Options > Dual-Purpose Pins. Please note that if you are using it as multi-device configuration mode, you cannot use nCEO pin as regular I/O after configuration.

    You can use this pin as a regular I/O pin in single-device configuration. During single-device configuration, you may leave this pin floating. In this case, connect this pin through an external 10-kΩ pull-up resistor to VCCPGM. For more information, you can refer to page 5 of this link: https://www.intel.fr/content/dam/www/programmable/us/en/pdfs/literature/dp/cyclone-v/pcg-01014.pdf

    Hope this helps.

    • SHard2's avatar
      SHard2
      Icon for Occasional Contributor rankOccasional Contributor
      5 years ago

      Hi

      Thank you for getting back to me, but unfortunately you may have misunderstood my question.

      For the 5CEFA9F23I7N device, the nCEO pin is within Bank 5A. I have VCCIO5A connected to 3V3, however VCCPGM is connected to 3V0.

      I am planning on using the nCEO pin as a regular IO pin (input only).

      In which case, is it safe to feed a 3V3 signal into the nCEO pin?

      I ask as the documentation only mentions using a 10K pull-up to VCCPGM.

      Best regards

      Simon