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Altera_Forum's avatar
Altera_Forum
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14 years ago

Symbol Files bdf newbie questions

Hi

I have an existing piece of code (vhd) that has single signals as well as multi-signal buses. I added the vhd file to my project, right clicked on it, and created a symbol file. I created a new .bdf file and added the symbol.

Is this correct/proper?

The symbol has a 16 bit bus of which I will use twelve bits. How do I connect a 12-bit bus to the upper 12 of the 16-bit bus? How do I break out the other bits?

Thanks for your help.

Rich

1 Reply

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

    The procedure you followed for bdf creation is correct.

    Regarding the bus, you need an intermediate device for matching the different bus widths.

    A common solution is using a latch for the upper (or lower) 4 bits. Your bus master will then make a double write (4bit + 12bit) whenever it needs to write a 16 bit data on your component. The first write is actually addressed to the latch, while the second one goes directly to your device, in addition to the extended bits previously latched.

    IMHO the optimal solution would be integrating this glue logic into your component, so that it exposes your 12 bit interface.