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Added kempston, autofire and enable autofire, enable turbo push buttons for GPIO1[32] and GPIO1[33]
2022-04-06 14:01:01 +03:00
------------------------------------------------------
-- FSM for a SDRAM controller
--
-- Version 0.1 - Ready to simulate
--
-- Author: Mike Field (hamster@snap.net.nz)
--
-- Feel free to use it however you would like, but
-- just drop me an email to say thanks.
-------------------------------------------------------
library ieee;
use ieee.std_logic_1164.all;
use ieee.std_logic_unsigned.all;
library unisim;
use unisim.vcomponents.all;
entity sdram_controller is
generic (
HIGH_BIT: integer := 24;
MHZ: integer := 96;
REFRESH_CYCLES: integer := 4096;
ADDRESS_BITS: integer := 12
);
PORT (
clock_100: in std_logic;
clock_100_delayed_3ns: in std_logic;
rst: in std_logic;
-- Signals to/from the SDRAM chip
DRAM_ADDR : OUT STD_LOGIC_VECTOR (ADDRESS_BITS-1 downto 0);
DRAM_BA : OUT STD_LOGIC_VECTOR (1 downto 0);
DRAM_CAS_N : OUT STD_LOGIC;
DRAM_CKE : OUT STD_LOGIC;
DRAM_CLK : OUT STD_LOGIC;
DRAM_CS_N : OUT STD_LOGIC;
DRAM_DQ : INOUT STD_LOGIC_VECTOR(15 downto 0);
DRAM_DQM : OUT STD_LOGIC_VECTOR(1 downto 0);
DRAM_RAS_N : OUT STD_LOGIC;
DRAM_WE_N : OUT STD_LOGIC;
pending: out std_logic;
--- Inputs from rest of the system
address : IN STD_LOGIC_VECTOR (HIGH_BIT downto 2);
req_read : IN STD_LOGIC;
req_write : IN STD_LOGIC;
data_out : OUT STD_LOGIC_VECTOR (31 downto 0);
data_out_valid : OUT STD_LOGIC;
data_in : IN STD_LOGIC_VECTOR (31 downto 0);
data_mask : IN STD_LOGIC_VECTOR (3 downto 0)
);
end entity;
architecture rtl of sdram_controller is
type reg is record
address : std_logic_vector(ADDRESS_BITS-1 downto 0);
bank : std_logic_vector( 1 downto 0);
init_counter : std_logic_vector(14 downto 0);
rf_counter : integer;
rf_pending : std_logic;
rd_pending : std_logic;
wr_pending : std_logic;
act_row : std_logic_vector(ADDRESS_BITS-1 downto 0);
act_ba : std_logic_vector(1 downto 0);
data_out_low : std_logic_vector(15 downto 0);
req_addr_q : std_logic_vector(HIGH_BIT downto 2);
req_data_write: std_logic_vector(31 downto 0);
req_mask : std_logic_vector(3 downto 0);
data_out_valid: std_logic;
dq_masks : std_logic_vector(1 downto 0);
tristate : std_logic;
end record;
signal r : reg;
signal n : reg;
signal rstate : std_logic_vector(8 downto 0);
signal nstate : std_logic_vector(8 downto 0);
signal rdata_write : std_logic_vector(15 downto 0);
signal ndata_write : std_logic_vector(15 downto 0);
-- Vectors for each SDRAM 'command'
--- CS_N, RAS_N, CAS_N, WE_N
constant cmd_nop : std_logic_vector(3 downto 0) := "0111";
constant cmd_read : std_logic_vector(3 downto 0) := "0101"; -- Must be sure A10 is low.
constant cmd_write : std_logic_vector(3 downto 0) := "0100";
constant cmd_act : std_logic_vector(3 downto 0) := "0011";
constant cmd_pre : std_logic_vector(3 downto 0) := "0010"; -- Must set A10 to '1'.
constant cmd_ref : std_logic_vector(3 downto 0) := "0001";
constant cmd_mrs : std_logic_vector(3 downto 0) := "0000"; -- Mode register set
-- State assignments
constant s_init_nop_id: std_logic_vector(4 downto 0) := "00000";
constant s_init_nop : std_logic_vector(8 downto 0) := s_init_nop_id & cmd_nop;
constant s_init_pre : std_logic_vector(8 downto 0) := s_init_nop_id & cmd_pre;
constant s_init_ref : std_logic_vector(8 downto 0) := s_init_nop_id & cmd_ref;
constant s_init_mrs : std_logic_vector(8 downto 0) := s_init_nop_id & cmd_mrs;
constant s_idle_id: std_logic_vector(4 downto 0) := "00001";
constant s_idle : std_logic_vector(8 downto 0) := s_idle_id & cmd_nop;
constant s_rf0_id: std_logic_vector(4 downto 0) := "00010";
constant s_rf0 : std_logic_vector(8 downto 0) := s_rf0_id & cmd_ref;
constant s_rf1_id: std_logic_vector(4 downto 0) := "00011";
constant s_rf1 : std_logic_vector(8 downto 0) := "00011" & cmd_nop;
constant s_rf2_id: std_logic_vector(4 downto 0) := "00100";
constant s_rf2 : std_logic_vector(8 downto 0) := "00100" & cmd_nop;
constant s_rf3_id: std_logic_vector(4 downto 0) := "00101";
constant s_rf3 : std_logic_vector(8 downto 0) := "00101" & cmd_nop;
constant s_rf4_id: std_logic_vector(4 downto 0) := "00110";
constant s_rf4 : std_logic_vector(8 downto 0) := "00110" & cmd_nop;
constant s_rf5_id: std_logic_vector(4 downto 0) := "00111";
constant s_rf5 : std_logic_vector(8 downto 0) := "00111" & cmd_nop;
constant s_ra0_id: std_logic_vector(4 downto 0) := "01000";
constant s_ra0 : std_logic_vector(8 downto 0) := "01000" & cmd_act;
constant s_ra1_id: std_logic_vector(4 downto 0) := "01001";
constant s_ra1 : std_logic_vector(8 downto 0) := "01001" & cmd_nop;
constant s_ra2_id: std_logic_vector(4 downto 0) := "01010";
constant s_ra2 : std_logic_vector(8 downto 0) := "01010" & cmd_nop;
constant s_dr0_id: std_logic_vector(4 downto 0) := "01011";
constant s_dr0 : std_logic_vector(8 downto 0) := "01011" & cmd_pre;
constant s_dr1_id: std_logic_vector(4 downto 0) := "01100";
constant s_dr1 : std_logic_vector(8 downto 0) := "01100" & cmd_nop;
constant s_wr0_id: std_logic_vector(4 downto 0) := "01101";
constant s_wr0 : std_logic_vector(8 downto 0) := "01101" & cmd_write;
constant s_wr1_id: std_logic_vector(4 downto 0) := "01110";
constant s_wr1 : std_logic_vector(8 downto 0) := "01110" & cmd_nop;
constant s_wr2_id: std_logic_vector(4 downto 0) := "01111";
constant s_wr2 : std_logic_vector(8 downto 0) := "01111" & cmd_nop;
constant s_wr3_id: std_logic_vector(4 downto 0) := "10000";
constant s_wr3 : std_logic_vector(8 downto 0) := "10000" & cmd_write;
constant s_rd0_id: std_logic_vector(4 downto 0) := "10001";
constant s_rd0 : std_logic_vector(8 downto 0) := "10001" & cmd_read;
constant s_rd1_id: std_logic_vector(4 downto 0) := "10010";
constant s_rd1 : std_logic_vector(8 downto 0) := "10010" & cmd_read;
constant s_rd2_id: std_logic_vector(4 downto 0) := "10011";
constant s_rd2 : std_logic_vector(8 downto 0) := "10011" & cmd_nop;
constant s_rd3_id: std_logic_vector(4 downto 0) := "10100";
constant s_rd3 : std_logic_vector(8 downto 0) := "10100" & cmd_read;
constant s_rd4_id: std_logic_vector(4 downto 0) := "10101";
constant s_rd4 : std_logic_vector(8 downto 0) := "10101" & cmd_read;
constant s_rd5_id: std_logic_vector(4 downto 0) := "10110";
constant s_rd5 : std_logic_vector(8 downto 0) := "10110" & cmd_read;
constant s_rd6_id: std_logic_vector(4 downto 0) := "10111";
constant s_rd6 : std_logic_vector(8 downto 0) := "10111" & cmd_nop;
constant s_rd7_id: std_logic_vector(4 downto 0) := "11000";
constant s_rd7 : std_logic_vector(8 downto 0) := "11000" & cmd_nop;
constant s_rd8_id: std_logic_vector(4 downto 0) := "11001";
constant s_rd8 : std_logic_vector(8 downto 0) := "11001" & cmd_nop;
constant s_rd9_id: std_logic_vector(4 downto 0) := "11011";
constant s_rd9 : std_logic_vector(8 downto 0) := "11011" & cmd_nop;
constant s_drdr0_id: std_logic_vector(4 downto 0) := "11101";
constant s_drdr0 : std_logic_vector(8 downto 0) := "11101" & cmd_pre;
constant s_drdr1_id: std_logic_vector(4 downto 0) := "11110";
constant s_drdr1 : std_logic_vector(8 downto 0) := "11110" & cmd_nop;
constant s_drdr2_id: std_logic_vector(4 downto 0) := "11111";
constant s_drdr2 : std_logic_vector(8 downto 0) := "11111" & cmd_nop;
signal addr_row : std_logic_vector(ADDRESS_BITS-1 downto 0);
signal addr_bank: std_logic_vector(1 downto 0);
constant COLUMN_HIGH: integer := HIGH_BIT - addr_row'LENGTH - addr_bank'LENGTH - 1; -- last 1 means 16 bit width
signal addr_col : std_logic_vector(7 downto 0);
signal captured : std_logic_vector(15 downto 0);
signal busy: std_logic;
constant tOPD: time := 2.1 ns;
constant tHZ: time := 8 ns;
signal dram_dq_dly : std_logic_vector(15 downto 0);
-- Debug only
signal debug_cmd: std_logic_vector(3 downto 0);
signal not_clock_100_delayed_3ns: std_logic;
constant RELOAD: integer := (((64000000/REFRESH_CYCLES)*MHZ)/1000) - 10;
attribute IOB: string;
signal i_DRAM_CS_N: std_logic;
attribute IOB of i_DRAM_CS_N: signal is "true";
signal i_DRAM_RAS_N: std_logic;
attribute IOB of i_DRAM_RAS_N: signal is "true";
signal i_DRAM_CAS_N: std_logic;
attribute IOB of i_DRAM_CAS_N: signal is "true";
signal i_DRAM_WE_N: std_logic;
attribute IOB of i_DRAM_WE_N: signal is "true";
signal i_DRAM_ADDR: std_logic_vector(ADDRESS_BITS-1 downto 0);
attribute IOB of i_DRAM_ADDR: signal is "true";
signal i_DRAM_BA: std_logic_vector(1 downto 0);
attribute IOB of i_DRAM_BA: signal is "true";
signal i_DRAM_DQM: std_logic_vector(1 downto 0);
attribute IOB of i_DRAM_DQM: signal is "true";
attribute IOB of rdata_write: signal is "true";
attribute IOB of captured: signal is "true";
signal i_DRAM_CLK: std_logic;
attribute fsm_encoding: string;
attribute fsm_encoding of nstate: signal is "user";
attribute fsm_encoding of rstate: signal is "user";
begin
debug_cmd <= rstate(3 downto 0);
-- Addressing is in 32 bit words - twice that of the DRAM width,
-- so each burst of four access two system words.
--addr_row <= address(23 downto 11);
--addr_bank <= address(10 downto 9);
process(r.req_addr_q)
begin
addr_bank <= r.req_addr_q(HIGH_BIT downto (HIGH_BIT-addr_bank'LENGTH)+1);
-- (24-2) downto (24-2 - 2 - 13 - 1)
-- 22 downto 6
addr_row <= --r.req_addr_q(HIGH_BIT-addr_bank'LENGTH downto COLUMN_HIGH+2);
r.req_addr_q(ADDRESS_BITS-1+9 downto 9);
addr_col <= (others => '0');
addr_col <= --r.req_addr_q(COLUMN_HIGH+1 downto 2) & "0";
r.req_addr_q(8 downto 2) & "0";
end process;
not_clock_100_delayed_3ns <= not clock_100_delayed_3ns;
clock: ODDR2
generic map (
DDR_ALIGNMENT => "NONE",
INIT => '0',
SRTYPE => "ASYNC")
port map (
D0 => '1',
D1 => '0',
Q => i_DRAM_CLK,
C0 => clock_100_delayed_3ns,
C1 => not_clock_100_delayed_3ns,
CE => '1',
R => '0',
S => '0'
);
DRAM_CKE <= '1';
DRAM_CLK <= transport i_DRAM_CLK after tOPD;
i_DRAM_CS_N <= transport rstate(3) after tOPD;
DRAM_CS_N <= i_DRAM_CS_N;
i_DRAM_RAS_N <= transport rstate(2) after tOPD;
DRAM_RAS_N <= i_DRAM_RAS_N;
i_DRAM_CAS_N <= transport rstate(1) after tOPD;
DRAM_CAS_N <= i_DRAM_CAS_N;
i_DRAM_WE_N <= transport rstate(0) after tOPD;
DRAM_WE_N <= i_DRAM_WE_N;
i_DRAM_ADDR <= transport r.address after tOPD;
DRAM_ADDR <= i_DRAM_ADDR;
i_DRAM_BA <= transport r.bank after tOPD;
DRAM_BA <= i_DRAM_BA;
i_DRAM_DQM <= transport r.dq_masks after tOPD;
DRAM_DQM <= i_DRAM_DQM;
DATA_OUT <= r.data_out_low & captured;--r.data_out_low & captured;
data_out_valid <= r.data_out_valid;
DRAM_DQ <= (others => 'Z') after tHZ when r.tristate='1' else rdata_write;
pending <= '1' when r.wr_pending='1' or r.rd_pending='1' else '0';
process (r, rstate, address, req_read, rdata_write, req_write, addr_row, addr_bank, addr_col, data_in, captured)
begin
-- copy the existing values
n <= r;
nstate <= rstate;
ndata_write <= rdata_write;
if req_read = '1' then
n.rd_pending <= '1';
if r.rd_pending='0' then
n.req_addr_q <= address;
end if;
end if;
if req_write = '1' then
n.wr_pending <= '1';
if r.wr_pending='0' then
n.req_addr_q <= address;
-- Queue data here
n.req_data_write <= data_in;
n.req_mask <= data_mask;
end if;
end if;
n.dq_masks <= "11";
-- first off, do we need to perform a refresh cycle ASAP?
if r.rf_counter = RELOAD then -- 781 = 64,000,000ns / 8192 / 10ns
n.rf_counter <= 0;
n.rf_pending <= '1';
else
-- only start looking for refreshes outside of the initialisation state.
if not(rstate(8 downto 4) = s_init_nop(8 downto 4)) then
n.rf_counter <= r.rf_counter + 1;
end if;
end if;
-- Set the data bus into HIZ, high and low bytes masked
--DRAM_DQ <= (others => 'Z');
n.tristate <= '0';
n.init_counter <= r.init_counter-1;
--ndata_write <= (others => DontCareValue);
n.data_out_valid <= '0'; -- alvie- here, no ?
-- Process the FSM
case rstate(8 downto 4) is
when s_init_nop_id => --s_init_nop(8 downto 4) =>
nstate <= s_init_nop;
n.address <= (others => '0');
n.bank <= (others => '0');
n.act_ba <= (others => '0');
n.rf_counter <= 0;
-- n.data_out_valid <= '1'; -- alvie- not here
-- T-130, precharge all banks.
if r.init_counter = "000000010000010" then
nstate <= s_init_pre;
n.address(10) <= '1';
end if;
-- T-127, T-111, T-95, T-79, T-63, T-47, T-31, T-15, the 8 refreshes
if r.init_counter(14 downto 7) = 0 and r.init_counter(3 downto 0) = 15 then
nstate <= s_init_ref;
end if;
-- T-3, the load mode register
if r.init_counter = 3 then
nstate <= s_init_mrs;
-- Mode register is as follows:
-- resvd wr_b OpMd CAS=3 Seq bust=1
n.address <= "00" & "0" & "00" & "011" & "0" & "000";
-- resvd
n.bank <= "00";
end if;
-- T-1 The switch to the FSM (first command will be a NOP
if r.init_counter = 1 then
nstate <= s_idle;
end if;
------------------------------
-- The Idle section
------------------------------
when s_idle_id =>
nstate <= s_idle;
-- do we have to activate a row?
if r.rd_pending = '1' or r.wr_pending = '1' then
nstate <= s_ra0;
n.address <= addr_row;
n.act_row <= addr_row;
n.bank <= addr_bank;
end if;
-- refreshes take priority over everything
if r.rf_pending = '1' then
nstate <= s_rf0;
n.rf_pending <= '0';
end if;
------------------------------
-- Row activation
-- s_ra2 is also the "idle with active row" state and provides
-- a resting point between operations on the same row
------------------------------
when s_ra0_id =>
nstate <= s_ra1;
when s_ra1_id =>
nstate <= s_ra2;
when s_ra2_id=>
-- we can stay in this state until we have something to do
nstate <= s_ra2;
n.tristate<='0';
if r.rf_pending = '1' then
nstate <= s_dr0;
n.address(10) <= '1';
else
-- If there is a read pending, deactivate the row
if r.rd_pending = '1' or r.wr_pending = '1' then
nstate <= s_dr0;
n.address(10) <= '1';
end if;
-- unless we have a read to perform on the same row? do that instead
if r.rd_pending = '1' and r.act_row = addr_row and addr_bank=r.bank then
nstate <= s_rd0;
n.address <= (others => '0');
n.address(addr_col'HIGH downto 0) <= addr_col;
n.bank <= addr_bank;
n.act_ba <= addr_bank;
n.dq_masks <= "00";
n.rd_pending <= '0';
--n.tristate<='1';
end if;
-- unless we have a write on the same row? writes take priroty over reads
if r.wr_pending = '1' and r.act_row = addr_row and addr_bank=r.bank then
nstate <= s_wr0;
n.address <= (others => '0');
n.address(addr_col'HIGH downto 0) <= addr_col;
ndata_write <= r.req_data_write(31 downto 16);
n.bank <= addr_bank;
n.act_ba <= addr_bank;
n.dq_masks<= not r.req_mask(3 downto 2);
n.wr_pending <= '0';
--n.tristate <= '0';
end if;
end if;
-- nstate <= s_dr0;
-- n.address(10) <= '1';
-- n.rd_pending <= r.rd_pending;
-- n.wr_pending <= r.wr_pending;
--n.tristate <= '0';
--end if;
------------------------------------------------------
-- Deactivate the current row and return to idle state
------------------------------------------------------
when s_dr0_id =>
nstate <= s_dr1;
when s_dr1_id =>
nstate <= s_idle;
------------------------------
-- The Refresh section
------------------------------
when s_rf0_id =>
nstate <= s_rf1;
when s_rf1_id =>
nstate <= s_rf2;
when s_rf2_id =>
nstate <= s_rf3;
when s_rf3_id =>
nstate <= s_rf4;
when s_rf4_id =>
nstate <= s_rf5;
when s_rf5_id =>
nstate <= s_idle;
------------------------------
-- The Write section
------------------------------
when s_wr0_id =>
nstate <= s_wr3;
n.bank <= addr_bank;
n.address(0) <= '1';
ndata_write <= r.req_data_write(15 downto 0);--data_in(31 downto 16);
--DRAM_DQ <= rdata_write;
n.dq_masks<= not r.req_mask(1 downto 0);
n.tristate <= '0';
when s_wr1_id => null;
when s_wr2_id =>
nstate <= s_dr0;
n.address(10) <= '1';
when s_wr3_id =>
-- Default to the idle+row active state
nstate <= s_ra2;
--DRAM_DQ <= rdata_write;
n.data_out_valid<='1'; -- alvie- ack write
n.tristate <= '0';
n.dq_masks<= "11";
-- If there is a read or write then deactivate the row
--if r.rd_pending = '1' or r.wr_pending = '1' then
-- nstate <= s_dr0;
-- n.address(10) <= '1';
--end if;
-- But if there is a read pending in the same row, do that
--if r.rd_pending = '1' and r.act_row = addr_row and r.act_ba = addr_bank then
-- nstate <= s_rd0;
-- n.address <= (others => '0');
-- n.address(addr_col'HIGH downto 0) <= addr_col;
-- n.bank <= addr_bank;
-- --n.act_ba <= addr_bank;
-- n.dq_masks <= "00";
-- n.rd_pending <= '0';
--end if;
-- unless there is a write pending in the same row, do that
--if r.wr_pending = '1' and r.act_row = addr_row and r.act_ba = addr_bank then
-- nstate <= s_wr0;
-- n.address <= (others => '0');
-- n.address(addr_col'HIGH downto 0) <= addr_col;
-- n.bank <= addr_bank;
--n.act_ba <= addr_bank;
-- n.dq_masks<= "00";
-- n.wr_pending <= '0';
--end if;
-- But always try and refresh if one is pending!
if r.rf_pending = '1' then
nstate <= s_wr2; --dr0;
--n.address(10) <= '1';
end if;
------------------------------
-- The Read section
------------------------------
when s_rd0_id => -- 10001
nstate <= s_rd1;
n.tristate<='1';
n.dq_masks <= "00";
n.address(0)<='1';
when s_rd1_id => -- 10010
nstate <= s_rd2;
n.dq_masks <= "00";
n.tristate<='1';
if r.rd_pending = '1' and r.act_row = addr_row and r.act_ba=addr_bank then
nstate <= s_rd3; -- Another request came, and we can pipeline -
n.address <= (others => '0');
n.address(addr_col'HIGH downto 0) <= addr_col;
n.bank <= addr_bank;
n.act_ba <= addr_bank;
n.dq_masks<= "00";
n.rd_pending <= '0';
end if;
when s_rd2_id => -- 10011
nstate <= s_rd7;
n.dq_masks <= "00";
n.tristate<='1';
when s_rd3_id => -- 10100
nstate <= s_rd4;
n.dq_masks <= "00";
n.address(0) <= '1';
n.tristate<='1';
-- Data is still not ready...
when s_rd4_id => -- 10101
nstate <= s_rd5;
n.dq_masks <= "00";
--n.address(0)<='1';
n.tristate<='1';
if r.rd_pending = '1' and r.act_row = addr_row and r.act_ba=addr_bank then
nstate <= s_rd5; -- Another request came, and we can pipeline -
n.address <= (others => '0');
n.address(addr_col'HIGH downto 0) <= addr_col;
n.bank <= addr_bank;
n.act_ba <= addr_bank;
n.dq_masks<= "00";
n.rd_pending <= '0';
else
nstate <= s_rd6; -- NOTE: not correct
end if;
--if r.rf_pending = '1' then
-- nstate <= s_drdr0;
-- n.address(10) <= '1';
-- n.rd_pending <= r.rd_pending; -- Keep request
--end if;
n.data_out_low <= captured;
n.data_out_valid <= '1';
when s_rd5_id =>
-- If a refresh is pending then always deactivate the row
--if r.rf_pending = '1' then
-- nstate <= s_drdr0;
-- n.address(10) <= '1';
--end if;
n.address(0) <= '1';
nstate <= s_rd4; -- Another request came, and we can pipeline -
n.dq_masks <= "00";
n.tristate<='1';
when s_rd6_id =>
nstate <= s_rd7;
n.dq_masks<= "00";
n.tristate<='1';
when s_rd7_id =>
nstate <= s_ra2;
n.data_out_low <= captured;
n.data_out_valid <= '1';
n.tristate<='1';
when s_rd8_id => null;
when s_rd9_id => null;
-- The Deactivate row during read section
------------------------------
when s_drdr0_id =>
nstate <= s_drdr1;
when s_drdr1_id =>
nstate <= s_drdr2;
n.data_out_low <= captured;
n.data_out_valid <= '1';
when s_drdr2_id =>
nstate <= s_idle;
if r.rf_pending = '1' then
nstate <= s_rf0;
end if;
if r.rd_pending = '1' or r.wr_pending = '1' then
nstate <= s_ra0;
n.address <= addr_row;
n.act_row <= addr_row;
n.bank <= addr_bank;
end if;
when others =>
nstate <= s_init_nop;
end case;
end process;
--- The clock driven logic
process (clock_100, n)
begin
if clock_100'event and clock_100 = '1' then
if rst='1' then
rstate <= (others => '0');
r.address <= (others => '0');
r.bank <= (others => '0');
r.init_counter <= "100000000000000";
-- synopsys translate_off
r.init_counter <= "000000100000000";
-- synopsys translate_on
r.rf_counter <= 0;
r.rf_pending <= '0';
r.rd_pending <= '0';
r.wr_pending <= '0';
r.act_row <= (others => '0');
r.data_out_low <= (others => '0');
r.data_out_valid <= '0';
r.dq_masks <= "11";
r.tristate<='1';
else
r <= n;
rstate <= nstate;
rdata_write <= ndata_write;
end if;
end if;
end process;
dram_dq_dly <= transport dram_dq after 1.9 ns;
-- process (clock_100_delayed_3ns, dram_dq_dly)
-- begin
-- if clock_100_delayed_3ns'event and clock_100_delayed_3ns = '1' then
-- captured <= dram_dq_dly;
-- end if;
-- end process;
process (clock_100)
begin
if falling_edge(clock_100) then
captured <= dram_dq_dly;
end if;
end process;
end rtl;
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