Unable to fit a partition even if OUTPUTS are declared Virtual Pins

Altera_Forum · ‎06-22-2012

Since I couldn't find any relevant answer in previous posts or tutorials, here's my 1st post, with a "tough" question.

I have a medium-size Quartus II v.9.0 project for Cyclone III EP3C5E144, which I want to partition, with 1 partition being a subdesign and the 2nd partition being everything else.

I followed the very clear step-by-step tutorial and everything went smooth, until I hit a nasty unexpected error.

My partitioned subdesign has an output to the parent level, which is a large parallel register (268 outputs).

--------- excerpt from .TDF ---------

frame_drop[267..0] : OUTPUT;

-------------------------------------

When generating the partition, outputs frame_drop[267..0] have been declared "Virtual Pin", and they are listed as "Virtual Pin", "On" in the Assignment Editor.

But when I Start a Compilation of the partition, it successfully completes Analysis and Synthesis, but fails to Fit, with error message:

"Can't place 208 pins with 2.5 V I/O standard because Fitter has only 88 such free pins available."

Now I wonder: why is Quartus trying to fit these 268 partition outputs to *physical* output pins, since it knows they are *Virtual* pins?

I am running a licensed Quartus II v.9.0 SP2 (License Type = Full Version in License Setup).

Thank you for your kind help,

Mauro Cerisola

Altera_Forum · ‎06-22-2012

Solved!

Turns out that when doing the "Generate Bottom-Up design partition scripts", Quartus automatically declares Virtual Pins the Output signals of the child partition, but only if they are used by the parent partition.

If the Child outputs are *unused*, they get assigned to an Output pin (!).

I had about half such outputs unused.

I had to manually declare ALL such outputs Virtual Pins.

Mauro Cerisola