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Altera_Forum's avatar
Altera_Forum
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21 years ago

External Memory

I may have an application that needs external memory devices on the same bus. It includes FLASH, SRAM, EEPROM, and other memory mapped devices. This is just an excersize, so we'll keep the data width for the FLASH at 16, the EEPROM at 8, and the SRAM at 32. I did the exersize in SOPC and connected 3 CFIs (common flash interfaces) to a tri-state avalone bus. It seems to work, but is this the right way to do it? I couldn't find any other devices that supports stuff like RAM and EEPROM. Looking at the block diagram in the CFI pfd, it looks like you can. Anyone have any ideas?

Rick

4 Replies

  • Altera_Forum's avatar
    Altera_Forum
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    21 years ago

    Rppolicy,

    Not quite; what you want is to use the "Interface to User Logic". This is for importing your own peripherals as well as just sprouting pins to the outside world.

    There are two tricks to this:

    1. Be sure to specify your data bus as type "inout" -- this tells SOPCB that the interface is bi-dir and needs to be mastered by the tri-state bridge; you can then hook up your new interface to the same tri-state master as your CFI flash.

    2. Use the "Shared" checkbox for any pins on the tri-state bus that will be common to multiple devices. For example, read, write, byte enable, and address are very often shared. Devices will usually have an "private" (non-shared) chipselect; just share the pins in such a way that agrees with how you're designing, or planning to design, your board.
  • Altera_Forum's avatar
    Altera_Forum
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    21 years ago

    http://forum.niosforum.com/work2/style_emoticons/<#EMO_DIR#>/huh.gif Hi,Jesse,

    My problem in my opinion is little bit similar to that of Rppolicy.

    My external memory is a flash(AMD29LV800B).I want to add the

    memory onto my dev board APEX20KE of JP8,JP9,JP10 . The reason

    is the program I made is too big to the flash available on the dev board,

    thus I have to find an approach to store the info of the program.

    But I really cannot figure out how to write data into it,and how to

    read data from it.

    It seems that my question is also about how to add an extenal memory device.

    So would you tell me what should I do to do something with the added

    flash?Many thanks! http://forum.niosforum.com/work2/style_emoticons/<#EMO_DIR#>/smile.gif

    Don
  • Altera_Forum's avatar
    Altera_Forum
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    21 years ago

    to upstairs

    I also want to add the flash(AMD29LV800B) onto my dev board APEX20KE .and the preset of cfi doesn&#39;t support this type.i don&#39;t know the timing value.and also the flash:amd29lv640 on the ep1s80 board.

    do you tell me? thank you.

    my email: zllxy993@163.net