Cyclone III I/Os assignment with Pin Planner

[Altera_Forum]

Hallo 

  I am working with my project on EP3C16Q240. 240 pins, 160 I/Os. In my project i need to connect 100 buttons or knobs. I have got also 16-pin bidirectional data busbetween FPGA and ATXmega and 5-pin control bus. All I need is just100 inputs (activated by connecting with GND) and 21 bidirectionalpins (3.3V).   So I opened a Pin Planer, thinking that5 minutes and everything will be done. I did not expected all thosestrange signs (Q,C, E, diff_n, diff_p etc.). I have got somequestions.   1. Should I really pay atention if pinis dq/dqs or diffrential pin or has another sign? Or I/O is just I/Oand no matter what is its optional function?  2. If not... Could i use diff_n anddiff_p in from one differential pair, as independent inputs? Or useDQS as I/O? 3. What is dev_oe and dev_clr pin? 4. What kind of pin would you use tocreate bidirectional bus with ATXMega?.   With regards: L.

[Altera_Forum]

1,2. I/O is just I/O, you can ignore diff_n, diff_p, dq, dqs, etc. The only exception is that dedicated clock pins can be used as general purpose INPUTS only. 

3. These are dual purpose pins that can be used as general purpose I/O. If you mistakenly assign a special purpose pin to an I/O, Quartus will flag an error. 4. Uses BIDIR (bi-directional).