+ Post New Thread
Results 1 to 5 of 5
  1. #1
    Advanced Member level 2
    Points: 3,983, Level: 14
    Achievements:
    7 years registered

    Join Date
    Apr 2011
    Posts
    544
    Helped
    24 / 24
    Points
    3,983
    Level
    14

    Is there special way to map address to SDR SDRAM?

    SDR SDRAM like other DRAMs contains banks, rows, columns. Thus, to get maximum efficiency, I assume that there would be some non-trivial way to translate memory address to bank, row and column address. Is this true? If so, then how is it usually done?

    •   AltAdvertisment

        
       

  2. #2
    Advanced Member level 5
    Points: 36,169, Level: 46
    Achievements:
    7 years registered

    Join Date
    Jun 2010
    Posts
    6,614
    Helped
    1927 / 1927
    Points
    36,169
    Level
    46

    Re: Is there special way to map address to SDR SDRAM?

    You read the data sheet.
    There will be a number of address pins each for row, bank and column. So you know how many of each by doing 2^(npins)



    •   AltAdvertisment

        
       

  3. #3
    Super Moderator
    Points: 245,559, Level: 100
    Awards:
    1st Helpful Member

    Join Date
    Jan 2008
    Location
    Bochum, Germany
    Posts
    42,657
    Helped
    13002 / 13002
    Points
    245,559
    Level
    100

    Re: Is there special way to map address to SDR SDRAM?

    The optimal scheme is almost trivial. You get fastest access when reading or writing full pages, thus the lower address bits are usually mapped to column address lines.


    1 members found this post helpful.

    •   AltAdvertisment

        
       

  4. #4
    Advanced Member level 3
    Points: 5,341, Level: 17

    Join Date
    Feb 2015
    Posts
    886
    Helped
    256 / 256
    Points
    5,341
    Level
    17

    Re: Is there special way to map address to SDR SDRAM?

    normally, the addresses are mapped either (bank, row, column) or (row, bank, column). You can choose a different scheme if you want though. placing bank at higher address bits has a little advantage if you have a small number of independent applications that are allocated a large memory space. placing bank at lower address bits allows a larger sequential region to have only column accesses once all banks are open.



  5. #5
    Full Member level 1
    Points: 834, Level: 6

    Join Date
    Aug 2016
    Location
    Bangalore, India
    Posts
    103
    Helped
    12 / 12
    Points
    834
    Level
    6

    Re: Is there special way to map address to SDR SDRAM?

    To access SDRAM in an efficient manner, it is better to follow linear addressing scheme as told in #4 that is combining row address, column address and bank address into a single vector and then increment this single vector to access different memory locations.

    But as switching from one row to another row is slow, therefore keeping the row address in MSB is recommended.

    Therefore I think (row,bank,column) will be efficient in terms of time.



--[[ ]]--