how to write SD ram

[mightycatniyander]

hi

this is the top level design of the SDRAM controller, can some one
point me out how to read data, process it (for ex: addition,
subtraction, etc) and write it back to memory. I know it can be done
with the sData signal, but how i don't know.

library IEEE;
use IEEE.std_logic_1164.all;
use WORK.test_board_core_pckg.all;

entity test_board is
port(
ce_n : out std_logic; -- Flash RAM chip-enable
sw2 : in std_logic; -- active-low pushbutton input
clk : in std_logic; -- main clock input from
external clock source
sclkfb : in std_logic; -- feedback SDRAM clock with
PCB delays
sclk : out std_logic; -- clock to SDRAM
cke : out std_logic; -- SDRAM clock-enable
cs_n : out std_logic; -- SDRAM chip-select
ras_n : out std_logic; -- SDRAM RAS
cas_n : out std_logic; -- SDRAM CAS
we_n : out std_logic; -- SDRAM write-enable
ba : out std_logic_vector( 1 downto 0); -- SDRAM bank-
address
sAddr : out std_logic_vector(12 downto 0); -- SDRAM address
bus
sData : inout std_logic_vector(15 downto 0); -- data bus to/from
SDRAM
dqmh : out std_logic; -- SDRAM DQMH
dqml : out std_logic; -- SDRAM DQML
s : out std_logic_vector(6 downto 0); -- 7-segment LED
pps : out std_logic_vector(6 downto 3) -- outputs to
parallel port status bits
);
end entity;

architecture arch of test_board is
begin

ce_n <= '1'; -- disable Flash RAM

u0 : test_board_core
generic map(
FREQ => 100_000,
PIPE_EN => true,
DATA_WIDTH => sData'length,
SADDR_WIDTH => sAddr'length,
NROWS => 8192,
NCOLS => 512,
BEG_ADDR => 16#00_0000#,
END_ADDR => 16#FF_FFFF#,
BEG_TEST => 16#00_0000#,
END_TEST => 16#FF_FFFF#
)
port map(
button_n => sw2,
clk => clk,
sclkfb => sclkfb,
sclk => sclk,
cke => cke,
cs_n => cs_n,
ras_n => ras_n,
cas_n => cas_n,
we_n => we_n,
ba => ba,
sAddr => sAddr,
sData => sData,
dqmh => dqmh,
dqml => dqml,
led => s,
heartBeat => pps(6)
);

end arch;

thanks

 

[kennheinrich]

hi

this is the top level design of the SDRAM controller, can some one
point me out how to read data, process it (for ex: addition,
subtraction, etc) and write it back to memory. I know it can be done
with the sData signal, but how i don't know.

library IEEE;
use IEEE.std_logic_1164.all;
use WORK.test_board_core_pckg.all;

entity test_board is
  port(
    ce_n   : out   std_logic;           -- Flash RAM chip-enable
    sw2    : in    std_logic;           -- active-low pushbutton input
    clk    : in    std_logic;           -- main clock input from
external clock source
    sclkfb : in    std_logic;           -- feedback SDRAM clock with
PCB delays
    sclk   : out   std_logic;           -- clock to SDRAM
    cke    : out   std_logic;           -- SDRAM clock-enable
    cs_n   : out   std_logic;           -- SDRAM chip-select
    ras_n  : out   std_logic;           -- SDRAM RAS
    cas_n  : out   std_logic;           -- SDRAM CAS
    we_n   : out   std_logic;           -- SDRAM write-enable
    ba     : out   std_logic_vector( 1 downto 0);  -- SDRAM bank-
address
    sAddr  : out   std_logic_vector(12 downto 0);  -- SDRAM address
bus
    sData  : inout std_logic_vector(15 downto 0);  -- data bus to/from
SDRAM
    dqmh   : out   std_logic;           -- SDRAM DQMH
    dqml   : out   std_logic;           -- SDRAM DQML
    s      : out   std_logic_vector(6 downto 0);  -- 7-segment LED
    pps    : out   std_logic_vector(6 downto 3)  -- outputs to
parallel port status bits
    );
end entity;

architecture arch of test_board is
begin

  ce_n <= '1';                          -- disable Flash RAM

  u0 : test_board_core
    generic map(
      FREQ        => 100_000,
      PIPE_EN     => true,
      DATA_WIDTH  => sData'length,
      SADDR_WIDTH => sAddr'length,
      NROWS       => 8192,
      NCOLS       => 512,
      BEG_ADDR    => 16#00_0000#,
      END_ADDR    => 16#FF_FFFF#,
      BEG_TEST    => 16#00_0000#,
      END_TEST    => 16#FF_FFFF#
      )
    port map(
      button_n    => sw2,
      clk         => clk,
      sclkfb      => sclkfb,
      sclk        => sclk,
      cke         => cke,
      cs_n        => cs_n,
      ras_n       => ras_n,
      cas_n       => cas_n,
      we_n        => we_n,
      ba          => ba,
      sAddr       => sAddr,
      sData       => sData,
      dqmh        => dqmh,
      dqml        => dqml,
      led         => s,
      heartBeat   => pps(6)
      );

end arch;

thanks

You need two things for sure: a schematic for the board, and a
datasheet for the SDRAM device in particular that you're talking to.
The ports you list suggest that this is the top level interface to an
SDRAM, not to a controller. You either need to find source code for a
controller for your chip, or write your own (which is a good
educational experience but consider it an "advanced" topic not ideally
suitable for a newbie). The datasheet will tell you what you have to
do with the SDRAM pins you list in order to make the memory accesses
happen.

- Kenn