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Altera_Forum's avatar
Altera_Forum
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14 years ago

Programming circuit

Hi, im trying to build a circuit board containing a cyclone-III and the necessary programming logic and I'ld like to keep it as cheap as possible.

I have the following questions:

I originally wrote the vhdl for a stratix-III but am now converting it to the cyclone.

I figure, the first step is to find out how much flash memory you need to store the fpga config. I do this by creating a .rbf file from my .sof file. My first problem is that the .rbf file is 5MB in size yet my vhdl is very simple ( one NCO and a multiplier basically, < 2% utilization on the Stratix-III.

This seems very large to me and would require a bigger and more expensive flash chip.

Secondly, assuming that the size is correct, I need to still buy a programmer. I was thinking of using a MAX V, again, the cheapest configuration and just using the parallel memory loader megafunction along with a 16MB flash chip.

All together, this costs about $10. $8 for the flash, ~$1 for the cpld.

Does this all sound legit? Does anyone have any tips that would be useful?

Thanks

Matt

4 Replies

  • Altera_Forum's avatar
    Altera_Forum
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    14 years ago

    You can interface controller between FPGA and flash, which would decompress the compressed image. The idea is to compress the RBF file with Your desired compressor and use microcontroller to do the decompression. Anyway, 16Mb isn't so much... >100Mb is a bigger problem :)

  • Altera_Forum's avatar
    Altera_Forum
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    14 years ago

    --- Quote Start ---

    The CPLD would be used to program the FPGA.

    --- Quote End ---

    Why can't you program the FPGA directly from the flash? I think that is the common way we use configuration schemes like Active Serial, Active Parallel.
  • Altera_Forum's avatar
    Altera_Forum
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    14 years ago

    Thanks wdshen.

    The CPLD would be used to program the FPGA.
  • Altera_Forum's avatar
    Altera_Forum
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    14 years ago

    5MBytes rbf for Stratix III is possible. You can check it on Altera Configuration Book (downloadable from the website). Also, the file size is fixed for a particular device, regardless of the design in it.

    One thing I am a little confused. You said you target device would change to Cyclone III. Why do you still need a CPLD?

    In terms of flash size, it depends on the target Cyclone III device you will use. Again you can check it on Altera Configuration Book. It lists the rbf data size for each Cyclone III device. (You can also consider using compression to reduce the file size.)