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Altera_Forum
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14 years ago

How to select I/O standard in pin planner

Hi, everyone

I'm trying to understand a sample program in Arria II Gx development Kit.

By assigning proper signals and clock to a connected SDI daughter board, the daughter board can feedback 147.5MHz to FPGA.

When I use 2.5V(default) as the I/O standard for the clock pin of 147.5MHz, my Verilog program cannot detect the rising edge and a simple counter cannot work. However, when I change the I/O standard to LVDS, the counter works.

After solving this problem, I check the pin planner of the sample program and find out that there are lots of I/O standards assigned to the pins of different components. For example: SSTL18-class I for DDR2 and 1.5V PCML for transceiver...

Is there any document related to the selection of I/O standard in pin planner?

Thanks.

1 Reply

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

    --- Quote Start ---

    Is there any document related to the selection of I/O standard in pin planner?

    --- Quote End ---

    Yes, its called the schematic for your board.

    FPGA I/O pins can be connected in a huge number of ways. The board designer will determine how many logic standards are needed, connect the power supplies appropriately, and then hopefully document the I/O standards required for the board.

    If you do not have a 'user manual' that describes the I/O assignments, then the schematic is the document you need to review. You can generally figure out the I/O standard required based on the VCCIO used on a particular bank, and from the data sheets of the devices that the FPGA is connected to.

    Cheers,

    Dave