Honored ContributorI am wondering what would be the safe state of the unused i/os on the arria ii gx development board. What I worry about is when I do not use a particular i/os it may still be connected on the board to some other device and I am wondering about what I should set these i/os to be?
Honored Contributorsetting the unused I/O to Input Tristate with weak pullup is a good idea.
Honored ContributorActually, I am wondering if doing this will cause problems with other devices on the a2gx development board. I am wondering if there is a quick list that Altera puts out indicating which i/os are absolutely necessary to be driven.
Honored ContributorYou may refer to the Arria II GX pin connection guideline: http://www.altera.com/literature/dp/arria-ii-gx/pcg-01007.pdf
Honored Contributorthe PCG is good if you're designing a board, but if you're using a devkit i'm not sure its all that helpful.
setting unused I/O to input with weak pullup shouldn't break anything, but it might set (unused) peripherals into unknown modes or other unexpected behavior. then again if you aren't using that particular feature you probably don't care what mode its in. you could take a look at the some of the included example designs to see what they have done with unused pins.Honored ContributorYes! input with weak pullups is what the example designs put unused i/os in.
Thanks.Honored Contributori should have been a bit clearer. i was also thinking of checking any pins that are driven to vcc or gnd in the top level of those project files, which would set any other required outputs to something other than unused.
