pin assignment - unused GPIO pins

[Altera_Forum]

Hi there, 

I´m using the GPIO pin header of the DE2 - 115.  I´m finished with the pin assignment, but there are several pins unused. But i don`t want to have them floated, so i want to define them.  I already read, that it is possible to connect them via 0 ohm resistor to gnd or Vcc. But in that case, they used a standard routing file from altera. I cannot use this file, but i want to define the gpio pins completely, to avoid damaging the board and the connected module.  Is it possible to: - find the unused pins automatically - define their states, but without using them in the project or is it necessary to include I/O pins in the project to assign the unused pins to a state?  Perhaps there is an other way to assign unused pins?   Thank you in advance.  kind regards

[Altera_Forum]

You have two options; 

 1. Define all pins used in a schematic as port in your top-level HDL file, and drive them with valid values.  2. Use the device option to "tri-state unused pins", or "enable weak pull-up on unused pins"  Given that a design may not use all FPGA pins on a device, I generally use both options.  Run the scripts associated with this DE0-nano design   http://www.alteraforum.com/forum/showthread.php?t=45927  and you'll see an example of;  1. A top-level design file that includes all I/O pins used on the DE0-nano board  2. A constraints.tcl script that assigns all the pins on the top-level, and some default constraints (including the weak pull-ups on unused pins constraint).  3. A synthesis script synth.tcl that automates the build.  This approach allows me to create a new project by copying the top-level HDL and synth.tcl script, making a few minor path adjustments for the new project, and then synthesize a new design.  I never have to worry about whether I have forgotten to assign pins correctly.  Cheers, Dave