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Altera_Forum's avatar
Altera_Forum
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10 years ago

Cyclone III I/Os assignment with Pin Planner

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.

1 Reply

  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    10 years ago

    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).