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Altera_Forum's avatar
Altera_Forum
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15 years ago

unused pin and Quartus option set

In the cyclone iii Pin Connection Guidelines, some types unused pins are recommended to connnect to VCCIO, and some are recommended to connnect to GND. I have two questions:

1. Which option should i choose in the "Reserve all unused pins" dialog in the Device and Pin Options? Because some connect to VCCIO and some connect to GND, so i am confused.

2. Someone tell me that i can set different option for different type unused pins. How can i do it? I use the Quartus 7.2, and i don't know how to set different options.

Thank you!

8 Replies

  • Altera_Forum's avatar
    Altera_Forum
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    15 years ago

    Choosing ''As input tri-stated with weak pull-up'' should be ok. That's the Quartus standard. With this setting, you don´t need to connect these pins to GND or VCCIO. Well, I've never done that.

    But make sure the MSEL pins are connected to GND or VCCA on the PCB, according to your configuration scheme.

    I´ve never seen different options for different unused pins. It´s a common setting in Quartus fot the entire FPGA.

    Success, Ton
  • Altera_Forum's avatar
    Altera_Forum
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    15 years ago

    Is there any problem if I connect the unused pins to GND or VCCIO and i choose the ''As input tri-stated with weak pull-up'' option at the same time?

  • Altera_Forum's avatar
    Altera_Forum
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    15 years ago

    The power dissipation will be greater than neccesary if you connect the pins to GND, due to the internal pull-up to VCCIO. But because it´s a weak pull-up, that´s no big deal.

    If you use a 0 Ohm resistor instead of a hardwired connection, you can leave it out if desired.

    Good luck, Ton
  • Altera_Forum's avatar
    Altera_Forum
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    15 years ago

    If you worry about static "power" dissipation, use bus-hold circuit instead of pull-up.

  • Altera_Forum's avatar
    Altera_Forum
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    15 years ago

    --- Quote Start ---

    Choosing ''As input tri-stated with weak pull-up'' should be ok. That's the Quartus standard.

    --- Quote End ---

    this is actually dependent on the target device family. for example, Stratix II is default to driving ground. this is an important subtlety, especially when using development kits
  • Altera_Forum's avatar
    Altera_Forum
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    15 years ago

    --- Quote Start ---

    this is actually dependent on the target device family. for example, Stratix II is default to driving ground. this is an important subtlety, especially when using development kits

    --- Quote End ---

    i'm using s60 board. if using the default setting "driving ground", then the board does not work.
  • Altera_Forum's avatar
    Altera_Forum
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    15 years ago

    --- Quote Start ---

    this is actually dependent on the target device family. for example, Stratix II is default to driving ground. this is an important subtlety, especially when using development kits

    --- Quote End ---

    Hi,

    I am using the BeMicro SDK development board. If I want to do some basic hardware development with the Cyclone IV but do not want to use any of the attached devices (i.e. the flash and the DDR RAM), I am not certain on how to properly set the unused pins.

    Should I set to input with weak pull-up on all of the pins that are connected to other devices?

    Thanks!

    -Josh
  • Altera_Forum's avatar
    Altera_Forum
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    15 years ago

    you should be able to leave Reserve all unused pins: As input tri-stated with weak pull-up in Assignments > Device and Pin Options > Unused Pins