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RLee42's avatar
RLee42
Icon for Occasional Contributor rankOccasional Contributor
6 years ago

How can I have weak pull-down for used input IO PINs on cyclone V?

Hi, I'd like to add weak pull-down resistors for used input I/O pins on cyclone V. ​However, I can only find an optional programmable pull-up resistor for each I/O pin in handbook. Is there any way ...
SreekumarR_G_Intel's avatar
SreekumarR_G_Intel
Icon for Frequent Contributor rankFrequent Contributor
6 years ago
Hello Ross, Thank you for questions,First I apologize for my delayed response. i am not sure why you are looking for pull down options , Here is the cyclone V pin out guidelines link below This is used to find the state the pin should if the pin are unused and also information about any external pull up /pull down requirement for Cyclone V. https://www.intel.com/content/dam/www/programmable/us/en/pdfs/literature/dp/cyclone-v/pcg-01014.pdf About the Bus hold , good question. From the block diagram of the IOE reference to figure 5-10, Assuming you have output (low impedance) of logic 1 and it set to hold the value...when you change to input buffer (i.e high impedance) i think there will be no problem to hold the logic if i understood correctly..but honestly i never tried on inout port. Can you kindly try and let me know ? Also let me know any if you have any other questions related to same topic ? Thank you , Regards, Sree
  • RLee42's avatar
    RLee42
    Icon for Occasional Contributor rankOccasional Contributor
    6 years ago

    Hi Sree,

    Thank you for your information.

    Actually, I'm using an existing board that has a cyclone V device on it. I'd just like to have some input PINs to keep logic 1 and some others to keep logic 0 when there are no connections. I do it by program instead of hardware currently and I'd like to know if there are some other better ways to achieve this.

    I also have interests on the features that I haven't used before, so I'll have a try to know about the Bus hold after this busy period and give you a feedback if I have any conclusion.

    Thank you.

    Best regards,

    Ross