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Altera_Forum
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17 years ago

SRAM switch and M4K

I read that FPGAs are either anti-fuse or SRAM switch and Cyclone II is a SRAM type FPGA.

Also, I found the Cyclone II has M4K RAM memory. I am wondering if M4K RAM and the SRAM switch are the same one.

If not, how are these SRAM switches set?

thanks

4 Replies

  • Altera_Forum's avatar
    Altera_Forum
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    17 years ago

    The configuration data in the .sof or .pof file program all the configuration RAM bits in the device. Those configuration RAM bits then control the configuration of all the device resources (logic resources in LABs, M9K blocks, PLLs, etc.).

  • Altera_Forum's avatar
    Altera_Forum
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    17 years ago

    Thanks for the reply. I am wondering if we can also manually change values in SRAM switches. Also, my another curiosity is: since SRAM stores both switch as well as logic element configuration, is it possible to which is which in .sof file?

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

    --- Quote Start ---

    Thanks for the reply. I am wondering if we can also manually change values in SRAM switches. Also, my another curiosity is: since SRAM stores both switch as well as logic element configuration, is it possible to which is which in .sof file?

    --- Quote End ---

    Hi,

    I assume that you would like to do some fast design cahnges without running a complete P&R run ???? For the purpose you can use the Quartus "Chip Editor".

    Kind regards

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

    --- Quote Start ---

    I am wondering if we can also manually change values in SRAM switches.

    --- Quote End ---

    The configuration RAM bits cannot be modified after the FPGA is configured. Some particular things can be changed after configuration though. For certain device families, you can change PLL settings, GX transceiver settings, or data stored in RAM blocks like M9K. To change M9K data after configuring (after the FPGA is running in user mode), use "Tools --> In-System Memory Content Editor". To change M9K initialization data before configuring but without recompiling, use "Processing --> Update Memory Initialization File".

    --- Quote Start ---

    Also, my another curiosity is: since SRAM stores both switch as well as logic element configuration, is it possible to which is which in .sof file?

    --- Quote End ---

    You can write configuration data to a text file format like .ttf or .hex, but you can't really tell what anything is in the configuration data. Also, what you are calling "SRAM switches" are the configuration RAM bits that control the logic element configuration--there isn't something separate in the .sof for logic element configuration.