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[SDRAM-Controller]

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- refactored: moved clockgen into phy
- removed async resets

git-svn-id: http://moon:8086/svn/vhdl/trunk@1153 cc03376c-175c-47c8-b038-4cd826a8556b
This commit is contained in:
jens
2015-05-22 17:49:58 +00:00
parent ba98d8e13e
commit 94665d9c19
8 changed files with 202 additions and 209 deletions
Download Patch File Download Diff File Expand all files Collapse all files
lib/SDRAM/ddr_sdr_v1_5/sim/tb_sdram_ctrl_frontend64_wb.wdo
+11 -12
View File
@@ -14,11 +14,10 @@ add wave -noupdate -format Literal -radix hexadecimal /tb_sdram_ctrl_frontend64_
add wave -noupdate -format Literal -radix hexadecimal /tb_sdram_ctrl_frontend64_wb/dat_o add wave -noupdate -format Literal -radix hexadecimal /tb_sdram_ctrl_frontend64_wb/dat_o
add wave -noupdate -format Literal -radix hexadecimal /tb_sdram_ctrl_frontend64_wb/dout_reg add wave -noupdate -format Literal -radix hexadecimal /tb_sdram_ctrl_frontend64_wb/dout_reg
add wave -noupdate -format Literal /tb_sdram_ctrl_frontend64_wb/dout_cnt add wave -noupdate -format Literal /tb_sdram_ctrl_frontend64_wb/dout_cnt
add wave -noupdate -format Logic /tb_sdram_ctrl_frontend64_wb/clk_fb add wave -noupdate -format Logic /tb_sdram_ctrl_frontend64_wb/sdram_ctrl_frontend64_wb/inst_sdram_ctrl_top/sdram_clk
add wave -noupdate -format Logic /tb_sdram_ctrl_frontend64_wb/clk_o add wave -noupdate -format Logic /tb_sdram_ctrl_frontend64_wb/sdram_ctrl_frontend64_wb/inst_sdram_ctrl_top/sdram_clk_fb
add wave -noupdate -format Logic /tb_sdram_ctrl_frontend64_wb/clk0_o add wave -noupdate -format Logic /tb_sdram_ctrl_frontend64_wb/sdram_ctrl_frontend64_wb/inst_sdram_ctrl_top/sdram_clk0
add wave -noupdate -format Logic /tb_sdram_ctrl_frontend64_wb/clk270_o add wave -noupdate -format Logic /tb_sdram_ctrl_frontend64_wb/sdram_ctrl_frontend64_wb/inst_sdram_ctrl_top/sdram_rst0
add wave -noupdate -format Logic /tb_sdram_ctrl_frontend64_wb/clk270var_o
add wave -noupdate -divider Part add wave -noupdate -divider Part
add wave -noupdate -format Logic /tb_sdram_ctrl_frontend64_wb/part_cs_n add wave -noupdate -format Logic /tb_sdram_ctrl_frontend64_wb/part_cs_n
add wave -noupdate -format Logic /tb_sdram_ctrl_frontend64_wb/part_we_n add wave -noupdate -format Logic /tb_sdram_ctrl_frontend64_wb/part_we_n
@@ -29,13 +28,13 @@ add wave -noupdate -format Literal /tb_sdram_ctrl_frontend64_wb/part_dm
add wave -noupdate -format Literal /tb_sdram_ctrl_frontend64_wb/part_dqs add wave -noupdate -format Literal /tb_sdram_ctrl_frontend64_wb/part_dqs
add wave -noupdate -format Literal -radix hexadecimal /tb_sdram_ctrl_frontend64_wb/part_addr add wave -noupdate -format Literal -radix hexadecimal /tb_sdram_ctrl_frontend64_wb/part_addr
add wave -noupdate -format Literal -radix hexadecimal /tb_sdram_ctrl_frontend64_wb/part_data add wave -noupdate -format Literal -radix hexadecimal /tb_sdram_ctrl_frontend64_wb/part_data
add wave -noupdate -format Literal -radix hexadecimal /tb_sdram_ctrl_frontend64_wb/sdram_ctrl_frontend64_wb/inst_sdram_ctrl/inst_sdram_ctrl/u_addr add wave -noupdate -format Literal -radix hexadecimal /tb_sdram_ctrl_frontend64_wb/sdram_ctrl_frontend64_wb/inst_sdram_ctrl_top/inst_sdram_ctrl/u_addr
add wave -noupdate -format Literal -radix hexadecimal /tb_sdram_ctrl_frontend64_wb/sdram_ctrl_frontend64_wb/inst_sdram_ctrl/inst_sdram_ctrl/u_col_addr add wave -noupdate -format Literal -radix hexadecimal /tb_sdram_ctrl_frontend64_wb/sdram_ctrl_frontend64_wb/inst_sdram_ctrl_top/inst_sdram_ctrl/u_col_addr
add wave -noupdate -format Literal -radix hexadecimal /tb_sdram_ctrl_frontend64_wb/sdram_ctrl_frontend64_wb/inst_sdram_ctrl/inst_sdram_ctrl/col_addr_reg add wave -noupdate -format Literal -radix hexadecimal /tb_sdram_ctrl_frontend64_wb/sdram_ctrl_frontend64_wb/inst_sdram_ctrl_top/inst_sdram_ctrl/col_addr_reg
add wave -noupdate -format Literal -radix hexadecimal /tb_sdram_ctrl_frontend64_wb/sdram_ctrl_frontend64_wb/inst_sdram_ctrl/inst_sdram_ctrl/u_row_addr add wave -noupdate -format Literal -radix hexadecimal /tb_sdram_ctrl_frontend64_wb/sdram_ctrl_frontend64_wb/inst_sdram_ctrl_top/inst_sdram_ctrl/u_row_addr
add wave -noupdate -format Literal -radix hexadecimal /tb_sdram_ctrl_frontend64_wb/sdram_ctrl_frontend64_wb/inst_sdram_ctrl/inst_sdram_ctrl/row_addr_reg add wave -noupdate -format Literal -radix hexadecimal /tb_sdram_ctrl_frontend64_wb/sdram_ctrl_frontend64_wb/inst_sdram_ctrl_top/inst_sdram_ctrl/row_addr_reg
add wave -noupdate -format Literal -radix hexadecimal /tb_sdram_ctrl_frontend64_wb/sdram_ctrl_frontend64_wb/inst_sdram_ctrl/inst_sdram_ctrl/u_bank_addr add wave -noupdate -format Literal -radix hexadecimal /tb_sdram_ctrl_frontend64_wb/sdram_ctrl_frontend64_wb/inst_sdram_ctrl_top/inst_sdram_ctrl/u_bank_addr
add wave -noupdate -format Literal -radix hexadecimal /tb_sdram_ctrl_frontend64_wb/sdram_ctrl_frontend64_wb/inst_sdram_ctrl/inst_sdram_ctrl/bank_addr_reg add wave -noupdate -format Literal -radix hexadecimal /tb_sdram_ctrl_frontend64_wb/sdram_ctrl_frontend64_wb/inst_sdram_ctrl_top/inst_sdram_ctrl/bank_addr_reg
add wave -noupdate -format Literal /tb_sdram_ctrl_frontend64_wb/sd_cmd add wave -noupdate -format Literal /tb_sdram_ctrl_frontend64_wb/sd_cmd
TreeUpdate [SetDefaultTree] TreeUpdate [SetDefaultTree]
WaveRestoreCursors {{Cursor 1} {38990166 ps} 0} WaveRestoreCursors {{Cursor 1} {38990166 ps} 0}
lib/SDRAM/ddr_sdr_v1_5/sim/tb_sdram_ctrl_frontend_wb.wdo
+17 -18
View File
@@ -15,18 +15,17 @@ add wave -noupdate -format Literal -radix hexadecimal /tb_sdram_ctrl_frontend_wb
add wave -noupdate -format Literal -radix hexadecimal /tb_sdram_ctrl_frontend_wb/dout_reg add wave -noupdate -format Literal -radix hexadecimal /tb_sdram_ctrl_frontend_wb/dout_reg
add wave -noupdate -format Literal /tb_sdram_ctrl_frontend_wb/dout_cnt add wave -noupdate -format Literal /tb_sdram_ctrl_frontend_wb/dout_cnt
add wave -noupdate -divider DEBUG add wave -noupdate -divider DEBUG
add wave -noupdate -format Literal -radix hexadecimal /tb_sdram_ctrl_frontend_wb/sdram_ctrl_frontend_wb/inst_sdram_ctrl/cmd_fifo_din add wave -noupdate -format Literal -radix hexadecimal /tb_sdram_ctrl_frontend_wb/sdram_ctrl_frontend_wb/inst_sdram_ctrl_top/cmd_fifo_din
add wave -noupdate -format Literal -radix hexadecimal /tb_sdram_ctrl_frontend_wb/sdram_ctrl_frontend_wb/inst_sdram_ctrl/cmd_fifo_dout add wave -noupdate -format Literal -radix hexadecimal /tb_sdram_ctrl_frontend_wb/sdram_ctrl_frontend_wb/inst_sdram_ctrl_top/cmd_fifo_dout
add wave -noupdate -format Logic /tb_sdram_ctrl_frontend_wb/sdram_ctrl_frontend_wb/inst_sdram_ctrl/cmd_fifo_re add wave -noupdate -format Logic /tb_sdram_ctrl_frontend_wb/sdram_ctrl_frontend_wb/inst_sdram_ctrl_top/cmd_fifo_re
add wave -noupdate -format Logic /tb_sdram_ctrl_frontend_wb/sdram_ctrl_frontend_wb/inst_sdram_ctrl/cmd_fifo_we add wave -noupdate -format Logic /tb_sdram_ctrl_frontend_wb/sdram_ctrl_frontend_wb/inst_sdram_ctrl_top/cmd_fifo_we
add wave -noupdate -format Logic /tb_sdram_ctrl_frontend_wb/sdram_ctrl_frontend_wb/inst_sdram_ctrl/cmd_fifo_full add wave -noupdate -format Logic /tb_sdram_ctrl_frontend_wb/sdram_ctrl_frontend_wb/inst_sdram_ctrl_top/cmd_fifo_full
add wave -noupdate -format Logic /tb_sdram_ctrl_frontend_wb/sdram_ctrl_frontend_wb/inst_sdram_ctrl/cmd_fifo_empty add wave -noupdate -format Logic /tb_sdram_ctrl_frontend_wb/sdram_ctrl_frontend_wb/inst_sdram_ctrl_top/cmd_fifo_empty
add wave -noupdate -format Logic /tb_sdram_ctrl_frontend_wb/clk_o add wave -noupdate -format Logic /tb_sdram_ctrl_frontend_wb/sdram_ctrl_frontend_wb/inst_sdram_ctrl_top/sdram_clk
add wave -noupdate -format Logic /tb_sdram_ctrl_frontend_wb/clk0_o add wave -noupdate -format Logic /tb_sdram_ctrl_frontend_wb/sdram_ctrl_frontend_wb/inst_sdram_ctrl_top/sdram_clk_fb
add wave -noupdate -format Logic /tb_sdram_ctrl_frontend_wb/clk270_o add wave -noupdate -format Logic /tb_sdram_ctrl_frontend_wb/sdram_ctrl_frontend_wb/inst_sdram_ctrl_top/sdram_clk0
add wave -noupdate -format Logic /tb_sdram_ctrl_frontend_wb/clk270var_o add wave -noupdate -format Logic /tb_sdram_ctrl_frontend_wb/sdram_ctrl_frontend_wb/inst_sdram_ctrl_top/sdram_rst0
add wave -noupdate -divider Part add wave -noupdate -divider Part
add wave -noupdate -format Logic /tb_sdram_ctrl_frontend_wb/clk0_o
add wave -noupdate -format Logic /tb_sdram_ctrl_frontend_wb/part_cs_n add wave -noupdate -format Logic /tb_sdram_ctrl_frontend_wb/part_cs_n
add wave -noupdate -format Logic /tb_sdram_ctrl_frontend_wb/part_we_n add wave -noupdate -format Logic /tb_sdram_ctrl_frontend_wb/part_we_n
add wave -noupdate -format Logic /tb_sdram_ctrl_frontend_wb/part_ras_n add wave -noupdate -format Logic /tb_sdram_ctrl_frontend_wb/part_ras_n
@@ -36,13 +35,13 @@ add wave -noupdate -format Literal /tb_sdram_ctrl_frontend_wb/part_dm
add wave -noupdate -format Literal /tb_sdram_ctrl_frontend_wb/part_dqs add wave -noupdate -format Literal /tb_sdram_ctrl_frontend_wb/part_dqs
add wave -noupdate -format Literal -radix hexadecimal /tb_sdram_ctrl_frontend_wb/part_addr add wave -noupdate -format Literal -radix hexadecimal /tb_sdram_ctrl_frontend_wb/part_addr
add wave -noupdate -format Literal -radix hexadecimal /tb_sdram_ctrl_frontend_wb/part_data add wave -noupdate -format Literal -radix hexadecimal /tb_sdram_ctrl_frontend_wb/part_data
add wave -noupdate -format Literal -radix hexadecimal /tb_sdram_ctrl_frontend_wb/sdram_ctrl_frontend_wb/inst_sdram_ctrl/inst_sdram_ctrl/u_addr add wave -noupdate -format Literal -radix hexadecimal /tb_sdram_ctrl_frontend_wb/sdram_ctrl_frontend_wb/inst_sdram_ctrl_top/inst_sdram_ctrl/u_addr
add wave -noupdate -format Literal -radix hexadecimal /tb_sdram_ctrl_frontend_wb/sdram_ctrl_frontend_wb/inst_sdram_ctrl/inst_sdram_ctrl/u_col_addr add wave -noupdate -format Literal -radix hexadecimal /tb_sdram_ctrl_frontend_wb/sdram_ctrl_frontend_wb/inst_sdram_ctrl_top/inst_sdram_ctrl/u_col_addr
add wave -noupdate -format Literal -radix hexadecimal /tb_sdram_ctrl_frontend_wb/sdram_ctrl_frontend_wb/inst_sdram_ctrl/inst_sdram_ctrl/col_addr_reg add wave -noupdate -format Literal -radix hexadecimal /tb_sdram_ctrl_frontend_wb/sdram_ctrl_frontend_wb/inst_sdram_ctrl_top/inst_sdram_ctrl/col_addr_reg
add wave -noupdate -format Literal -radix hexadecimal /tb_sdram_ctrl_frontend_wb/sdram_ctrl_frontend_wb/inst_sdram_ctrl/inst_sdram_ctrl/u_row_addr add wave -noupdate -format Literal -radix hexadecimal /tb_sdram_ctrl_frontend_wb/sdram_ctrl_frontend_wb/inst_sdram_ctrl_top/inst_sdram_ctrl/u_row_addr
add wave -noupdate -format Literal -radix hexadecimal /tb_sdram_ctrl_frontend_wb/sdram_ctrl_frontend_wb/inst_sdram_ctrl/inst_sdram_ctrl/row_addr_reg add wave -noupdate -format Literal -radix hexadecimal /tb_sdram_ctrl_frontend_wb/sdram_ctrl_frontend_wb/inst_sdram_ctrl_top/inst_sdram_ctrl/row_addr_reg
add wave -noupdate -format Literal -radix hexadecimal /tb_sdram_ctrl_frontend_wb/sdram_ctrl_frontend_wb/inst_sdram_ctrl/inst_sdram_ctrl/u_bank_addr add wave -noupdate -format Literal -radix hexadecimal /tb_sdram_ctrl_frontend_wb/sdram_ctrl_frontend_wb/inst_sdram_ctrl_top/inst_sdram_ctrl/u_bank_addr
add wave -noupdate -format Literal -radix hexadecimal /tb_sdram_ctrl_frontend_wb/sdram_ctrl_frontend_wb/inst_sdram_ctrl/inst_sdram_ctrl/bank_addr_reg add wave -noupdate -format Literal -radix hexadecimal /tb_sdram_ctrl_frontend_wb/sdram_ctrl_frontend_wb/inst_sdram_ctrl_top/inst_sdram_ctrl/bank_addr_reg
add wave -noupdate -format Literal /tb_sdram_ctrl_frontend_wb/sd_cmd add wave -noupdate -format Literal /tb_sdram_ctrl_frontend_wb/sd_cmd
TreeUpdate [SetDefaultTree] TreeUpdate [SetDefaultTree]
WaveRestoreCursors {{Cursor 1} {199582900 ps} 0} WaveRestoreCursors {{Cursor 1} {199582900 ps} 0}
lib/SDRAM/ddr_sdr_v1_5/src/ddr_phy_virtex4.vhd
+89 -37
View File
@@ -31,15 +31,21 @@ use work.sdram_types.all;
Library UNISIM; Library UNISIM;
use UNISIM.vcomponents.all; use UNISIM.vcomponents.all;
entity ddr_phy is entity sdram_phy is
Port ( Generic
sys_rst : in STD_LOGIC; (
sys_clk0 : in STD_LOGIC; f_sdrclk : real := 100.0
sys_clk270 : in STD_LOGIC; );
Port
(
rst : in STD_LOGIC;
clk : in STD_LOGIC;
clk_fb : in STD_LOGIC;
clk0_out : out STD_LOGIC;
rst0_out : out STD_LOGIC;
u_tag_in : in user_tag_t; u_tag_in : in user_tag_t;
u_tag_rd : out user_tag_t; u_tag_rd : out user_tag_t;
u_tag_wr : out user_tag_t; u_tag_wr : out user_tag_t;
read_clk : in STD_LOGIC;
phy_ctrl : in phy_ctrl_t; phy_ctrl : in phy_ctrl_t;
part_ctrl : in part_ctrl_t; part_ctrl : in part_ctrl_t;
sdr_data_w : in unsigned(SDR_DATA_WIDTH-1 downto 0); sdr_data_w : in unsigned(SDR_DATA_WIDTH-1 downto 0);
@@ -60,9 +66,9 @@ entity ddr_phy is
part_ras_n : out STD_LOGIC; part_ras_n : out STD_LOGIC;
part_cke : out STD_LOGIC part_cke : out STD_LOGIC
); );
end ddr_phy; end sdram_phy;
architecture tech of ddr_phy is architecture tech of sdram_phy is
signal dqs_drive : std_logic; signal dqs_drive : std_logic;
signal drive : std_logic; signal drive : std_logic;
@@ -77,16 +83,56 @@ architecture tech of ddr_phy is
signal we_reg : std_logic; signal we_reg : std_logic;
signal read_en : std_logic; signal read_en : std_logic;
signal clk0 : std_logic;
signal rst0 : std_logic;
signal clk_rd : std_logic;
signal clk_wr : std_logic;
signal locked : std_logic;
signal error : std_logic;
type u_tag_array_t is array (natural range 0 to 4) of user_tag_t; type u_tag_array_t is array (natural range 0 to 4) of user_tag_t;
signal u_tag_pipe : u_tag_array_t; signal u_tag_pipe : u_tag_array_t;
begin begin
clk0_out <= clk0;
rst0_out <= rst0;
------------------------------------------------------------------------------------------------------------------------------------------------
inst_clockgen : entity work.clockgen
GENERIC MAP
(
clk_in_freq => f_sdrclk,
clk0_out_phaseshift => 0,
clk1_out_phaseshift => 0
)
PORT MAP
(
-- Clocks and Reset
rst => rst, -- external async reset, low active
clk_in => clk, -- system clock (e.g. 100MHz), from board
clk_fb_in => clk_fb, -- feedback clock
clk0_0_out => clk0, -- System clock #0, dcm#0 output 0°
clk0_270_out => clk_wr, -- System clock #0, dcm#0 output 270°
clk1_0_out => open, -- System clock #1 (e.g. clock for DDR-SDRAM data capture), dcm#1 output 0°
clk1_270_out => clk_rd, -- System clock #1 (e.g. clock for DDR-SDRAM data capture), dcm#1 output 270°
locked_out => locked, -- DCM locked status
error_out => error
);
rst0_gen:
process(clk0)
begin
if rising_edge(clk0) then
rst0 <= not locked;
end if;
end process;
------------------------------------------------------------------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------------------------------------------------------------------
utag_pipe: utag_pipe:
process(sys_rst, sys_clk0) process(clk0)
begin begin
if rising_edge(sys_clk0) then if rising_edge(clk0) then
for i in u_tag_pipe'length-1 downto 1 loop for i in u_tag_pipe'length-1 downto 1 loop
u_tag_pipe(i) <= u_tag_pipe(i-1); u_tag_pipe(i) <= u_tag_pipe(i-1);
end loop; end loop;
@@ -97,29 +143,31 @@ utag_pipe:
end process; end process;
WE_REGISTER: WE_REGISTER:
process(sys_rst, sys_clk0) process(clk0)
begin begin
if sys_rst = '1' then if rising_edge(clk0) then
if rst0 = '1' then
we_reg <= '0'; we_reg <= '0';
elsif rising_edge(sys_clk0) then else
we_reg <= phy_ctrl.we; we_reg <= phy_ctrl.we;
end if; end if;
end if;
end process; end process;
DATA_DRIVE_GEN: DATA_DRIVE_GEN:
process(sys_clk0) process(clk0)
begin begin
if falling_edge(sys_clk0) then if falling_edge(clk0) then
dqs_rst <= not we_reg; dqs_rst <= not we_reg;
drive <= we_reg; drive <= we_reg;
end if; end if;
end process; end process;
DQS_DRIVE_GEN: DQS_DRIVE_GEN:
process(sys_clk0) process(clk0)
variable p : unsigned(1 downto 0); variable p : unsigned(1 downto 0);
begin begin
if rising_edge(sys_clk0) then if rising_edge(clk0) then
if phy_ctrl.drive_en = '1' then if phy_ctrl.drive_en = '1' then
p := (others => '1'); p := (others => '1');
else else
@@ -140,7 +188,7 @@ ODDR_clk_p : ODDR
) )
port map ( port map (
Q => part_clk_p, -- 1-bit DDR output Q => part_clk_p, -- 1-bit DDR output
C => sys_clk0, -- 1-bit clock input C => clk0, -- 1-bit clock input
CE => '1', -- 1-bit clock enable input CE => '1', -- 1-bit clock enable input
D1 => '1', -- 1-bit data input (positive edge) D1 => '1', -- 1-bit data input (positive edge)
D2 => '0', -- 1-bit data input (negative edge) D2 => '0', -- 1-bit data input (negative edge)
@@ -157,7 +205,7 @@ ODDR_clk_n : ODDR
) )
port map ( port map (
Q => part_clk_n, -- 1-bit DDR output Q => part_clk_n, -- 1-bit DDR output
C => sys_clk0, -- 1-bit clock input C => clk0, -- 1-bit clock input
CE => '1', -- 1-bit clock enable input CE => '1', -- 1-bit clock enable input
D1 => '0', -- 1-bit data input (positive edge) D1 => '0', -- 1-bit data input (positive edge)
D2 => '1', -- 1-bit data input (negative edge) D2 => '1', -- 1-bit data input (negative edge)
@@ -179,7 +227,7 @@ gen_ddr_data_out:
) )
port map ( port map (
Q => ddr_data_w(n), -- 1-bit DDR output Q => ddr_data_w(n), -- 1-bit DDR output
C => sys_clk270, -- 1-bit clock input C => clk_wr, -- 1-bit clock input
CE => '1', -- 1-bit clock enable input CE => '1', -- 1-bit clock enable input
D1 => sdr_data_w(n + DDR_DATA_WIDTH), -- 1-bit data input (positive edge) D1 => sdr_data_w(n + DDR_DATA_WIDTH), -- 1-bit data input (positive edge)
D2 => sdr_data_w(n), -- 1-bit data input (negative edge) D2 => sdr_data_w(n), -- 1-bit data input (negative edge)
@@ -189,9 +237,9 @@ gen_ddr_data_out:
end generate gen_ddr_data_out; end generate gen_ddr_data_out;
-- Sample tristate on clock90 -- Sample tristate on clock90
process (sys_clk270) process (clk_wr)
begin begin
if rising_edge(sys_clk270) then if rising_edge(clk_wr) then
for n in 0 to DDR_DATA_WIDTH-1 loop for n in 0 to DDR_DATA_WIDTH-1 loop
drive270(n) <= drive; drive270(n) <= drive;
end loop; end loop;
@@ -218,7 +266,7 @@ gen_ddr_dm_out:
) )
port map ( port map (
Q => part_dm(n), -- 1-bit DDR output Q => part_dm(n), -- 1-bit DDR output
C => sys_clk270, -- 1-bit clock input C => clk_wr, -- 1-bit clock input
CE => '1', -- 1-bit clock enable input CE => '1', -- 1-bit clock enable input
D1 => sdr_dm(n + DDR_DM_WIDTH), -- 1-bit data input (positive edge) D1 => sdr_dm(n + DDR_DM_WIDTH), -- 1-bit data input (positive edge)
D2 => sdr_dm(n), -- 1-bit data input (negative edge) D2 => sdr_dm(n), -- 1-bit data input (negative edge)
@@ -241,7 +289,7 @@ gen_dqs_out:
) )
port map ( port map (
Q => dqs(n), -- 1-bit DDR output Q => dqs(n), -- 1-bit DDR output
C => sys_clk0, -- 1-bit clock input C => clk0, -- 1-bit clock input
CE => '1', -- 1-bit clock enable input CE => '1', -- 1-bit clock enable input
D2 => '0', -- 1-bit data input (positive edge) D2 => '0', -- 1-bit data input (positive edge)
D1 => '1', -- 1-bit data input (negative edge) D1 => '1', -- 1-bit data input (negative edge)
@@ -251,10 +299,10 @@ gen_dqs_out:
end generate gen_dqs_out; end generate gen_dqs_out;
-- Tristate-Control fuer dqs -- Tristate-Control fuer dqs
process (sys_clk0) is process (clk0) is
variable zctrl : boolean; variable zctrl : boolean;
begin begin
if rising_edge(sys_clk0) then if rising_edge(clk0) then
if dqs_drive = '1' then if dqs_drive = '1' then
zctrl := false; zctrl := false;
else else
@@ -275,21 +323,23 @@ gen_out_mux_dqs:
end generate gen_out_mux_dqs; end generate gen_out_mux_dqs;
------------------------------------------------------------------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------------------------------------------------------------------
process (sys_rst, sys_clk0) is process (clk0) is
begin begin
if sys_rst = '1' then if rising_edge(clk0) then
if rst0 = '1' then
part_ctrl_reg.cmd <= COMMAND(SD_DESELECT); part_ctrl_reg.cmd <= COMMAND(SD_DESELECT);
part_ctrl_reg.ba <= (others=>'0'); part_ctrl_reg.ba <= (others=>'0');
part_ctrl_reg.addr <= (others=>'0'); part_ctrl_reg.addr <= (others=>'0');
part_ctrl_reg.cke <= '0'; part_ctrl_reg.cke <= '0';
elsif rising_edge(sys_clk0) then else
part_ctrl_reg <= part_ctrl; part_ctrl_reg <= part_ctrl;
end if; end if;
end if;
end process; end process;
process (sys_clk0) is process (clk0) is
begin begin
if falling_edge(sys_clk0) then if falling_edge(clk0) then
part_ras_n <= part_ctrl_reg.cmd.ras_n; part_ras_n <= part_ctrl_reg.cmd.ras_n;
part_cas_n <= part_ctrl_reg.cmd.cas_n; part_cas_n <= part_ctrl_reg.cmd.cas_n;
part_we_n <= part_ctrl_reg.cmd.we_n; part_we_n <= part_ctrl_reg.cmd.we_n;
@@ -318,7 +368,7 @@ gen_ddr_data_in:
( (
Q1 => data_r(n), -- 1-bit output for positive edge of clock Q1 => data_r(n), -- 1-bit output for positive edge of clock
Q2 => data_r(n + DDR_DATA_WIDTH), -- 1-bit output for negative edge of clock Q2 => data_r(n + DDR_DATA_WIDTH), -- 1-bit output for negative edge of clock
C => read_clk, -- 1-bit clock input C => clk_rd, -- 1-bit clock input
CE => read_en, -- 1-bit clock enable input CE => read_en, -- 1-bit clock enable input
D => part_data(n), -- 1-bit DDR data input D => part_data(n), -- 1-bit DDR data input
R => '0', -- 1-bit reset R => '0', -- 1-bit reset
@@ -328,23 +378,24 @@ gen_ddr_data_in:
data_sample_stage: data_sample_stage:
process (sys_clk0) process (clk0)
begin begin
if falling_edge(sys_clk0) then if falling_edge(clk0) then
data_reg_r <= data_r; data_reg_r <= data_r;
end if; end if;
end process; end process;
misc_flags_and_data_out: misc_flags_and_data_out:
process (sys_rst, sys_clk0) process (clk0)
variable p : unsigned(3 downto 0); variable p : unsigned(3 downto 0);
begin begin
if sys_rst = '1' then if rising_edge(clk0) then
if rst0 = '1' then
p := (others => '0'); p := (others => '0');
read_en <= '0'; read_en <= '0';
sdr_data_vld <= '0'; sdr_data_vld <= '0';
sdr_data_req_w <= '0'; sdr_data_req_w <= '0';
elsif rising_edge(sys_clk0) then else
sdr_data_r <= data_reg_r; sdr_data_r <= data_reg_r;
if p(3) = '1' then if p(3) = '1' then
u_tag_rd <= u_tag_pipe(4); u_tag_rd <= u_tag_pipe(4);
@@ -361,6 +412,7 @@ misc_flags_and_data_out:
p := p(p'left-1 downto 0) & '0'; p := p(p'left-1 downto 0) & '0';
end if; end if;
end if; end if;
end if;
end process; end process;
------------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------------
lib/SDRAM/ddr_sdr_v1_5/src/sdram_ctrl_frontend64_wb.vhd
+10 -10
View File
@@ -41,9 +41,8 @@ entity sdram_ctrl_frontend64_wb is
( (
RST_I : in STD_LOGIC; RST_I : in STD_LOGIC;
CLK_I : in STD_LOGIC; CLK_I : in STD_LOGIC;
SDRAM_CLK0_I : in STD_LOGIC; SDRAM_CLK_I : in STD_LOGIC;
SDRAM_CLK270_I : in STD_LOGIC; SDRAM_CLK_FB_I : in STD_LOGIC;
SDRAM_CLK270VAR_I : in STD_LOGIC;
CYC_I : in STD_LOGIC; CYC_I : in STD_LOGIC;
STB_I : in STD_LOGIC; STB_I : in STD_LOGIC;
@@ -75,7 +74,8 @@ end sdram_ctrl_frontend64_wb;
architecture struct of sdram_ctrl_frontend64_wb is architecture struct of sdram_ctrl_frontend64_wb is
-- Number of user data words for simulation signal SDRAM_CLK0 : std_logic;
signal u_addr : user_addr_t; signal u_addr : user_addr_t;
signal u_tag_in : user_tag_t; signal u_tag_in : user_tag_t;
signal u_tag_rd : user_tag_t; signal u_tag_rd : user_tag_t;
@@ -167,7 +167,7 @@ begin
( (
rst => RST_I, rst => RST_I,
clk_w => CLK_I, clk_w => CLK_I,
clk_r => SDRAM_CLK0_I, clk_r => SDRAM_CLK0,
we => write_fifo_we, we => write_fifo_we,
re => write_fifo_re, re => write_fifo_re,
fifo_full => write_fifo_full, fifo_full => write_fifo_full,
@@ -188,7 +188,7 @@ begin
PORT MAP PORT MAP
( (
rst => RST_I, rst => RST_I,
clk_w => SDRAM_CLK0_I, clk_w => SDRAM_CLK0,
clk_r => CLK_I, clk_r => CLK_I,
we => read_fifo_we, we => read_fifo_we,
re => read_fifo_re, re => read_fifo_re,
@@ -201,7 +201,7 @@ begin
); );
-- DDR SDRAM Controller Core -- DDR SDRAM Controller Core
inst_sdram_ctrl : entity work.sdram_ctrl_top inst_sdram_ctrl_top : entity work.sdram_ctrl_top
Generic map Generic map
( (
BL => BL, BL => BL,
@@ -215,9 +215,9 @@ begin
sys_rst_in => RST_I, sys_rst_in => RST_I,
sys_clk_in => CLK_I, sys_clk_in => CLK_I,
sdram_clk0_in => SDRAM_CLK0_I, sdram_clk => SDRAM_CLK_I,
sdram_clk270_in => SDRAM_CLK270_I, sdram_clk_fb => SDRAM_CLK_FB_I,
sdram_clk270_rd_in => SDRAM_CLK270VAR_I, sdram_clk_out => SDRAM_CLK0,
-- User interface -- User interface
u_data_vld => u_data_vld, u_data_vld => u_data_vld,
lib/SDRAM/ddr_sdr_v1_5/src/sdram_ctrl_frontend_wb.vhd
+10 -10
View File
@@ -41,9 +41,8 @@ entity sdram_ctrl_frontend_wb is
( (
RST_I : in STD_LOGIC; RST_I : in STD_LOGIC;
CLK_I : in STD_LOGIC; CLK_I : in STD_LOGIC;
SDRAM_CLK0_I : in STD_LOGIC; SDRAM_CLK_I : in STD_LOGIC;
SDRAM_CLK270_I : in STD_LOGIC; SDRAM_CLK_FB_I : in STD_LOGIC;
SDRAM_CLK270VAR_I : in STD_LOGIC;
CYC_I : in STD_LOGIC; CYC_I : in STD_LOGIC;
STB_I : in STD_LOGIC; STB_I : in STD_LOGIC;
@@ -75,7 +74,8 @@ end sdram_ctrl_frontend_wb;
architecture struct of sdram_ctrl_frontend_wb is architecture struct of sdram_ctrl_frontend_wb is
-- Number of user data words for simulation signal SDRAM_CLK0 : std_logic;
signal u_addr : user_addr_t; signal u_addr : user_addr_t;
signal u_tag_in : user_tag_t; signal u_tag_in : user_tag_t;
signal u_tag_rd : user_tag_t; signal u_tag_rd : user_tag_t;
@@ -167,7 +167,7 @@ begin
( (
rst => RST_I, rst => RST_I,
clk_w => CLK_I, clk_w => CLK_I,
clk_r => SDRAM_CLK0_I, clk_r => SDRAM_CLK0,
we => write_fifo_we, we => write_fifo_we,
re => write_fifo_re, re => write_fifo_re,
fifo_full => write_fifo_full, fifo_full => write_fifo_full,
@@ -188,7 +188,7 @@ begin
PORT MAP PORT MAP
( (
rst => RST_I, rst => RST_I,
clk_w => SDRAM_CLK0_I, clk_w => SDRAM_CLK0,
clk_r => CLK_I, clk_r => CLK_I,
we => read_fifo_we, we => read_fifo_we,
re => read_fifo_re, re => read_fifo_re,
@@ -201,7 +201,7 @@ begin
); );
-- DDR SDRAM Controller Core -- DDR SDRAM Controller Core
inst_sdram_ctrl : entity work.sdram_ctrl_top inst_sdram_ctrl_top : entity work.sdram_ctrl_top
Generic map Generic map
( (
BL => BL, BL => BL,
@@ -215,9 +215,9 @@ begin
sys_rst_in => RST_I, sys_rst_in => RST_I,
sys_clk_in => CLK_I, sys_clk_in => CLK_I,
sdram_clk0_in => SDRAM_CLK0_I, sdram_clk => SDRAM_CLK_I,
sdram_clk270_in => SDRAM_CLK270_I, sdram_clk_fb => SDRAM_CLK_FB_I,
sdram_clk270_rd_in => SDRAM_CLK270VAR_I, sdram_clk_out => SDRAM_CLK0,
-- User interface -- User interface
u_data_vld => u_data_vld, u_data_vld => u_data_vld,
lib/SDRAM/ddr_sdr_v1_5/src/sdram_ctrl_top.vhd
+20 -12
View File
@@ -41,9 +41,9 @@ entity sdram_ctrl_top is
sys_rst_in : in STD_LOGIC; sys_rst_in : in STD_LOGIC;
sys_clk_in : in STD_LOGIC; sys_clk_in : in STD_LOGIC;
sdram_clk0_in : in STD_LOGIC; sdram_clk : in STD_LOGIC;
sdram_clk270_in : in STD_LOGIC; sdram_clk_fb : in STD_LOGIC;
sdram_clk270_rd_in : in STD_LOGIC; sdram_clk_out : out STD_LOGIC;
-- User interface -- User interface
u_data_vld : out STD_LOGIC; u_data_vld : out STD_LOGIC;
@@ -79,6 +79,8 @@ end sdram_ctrl_top;
architecture rtl of sdram_ctrl_top is architecture rtl of sdram_ctrl_top is
signal sdram_clk0 : std_logic;
signal sdram_rst0 : std_logic;
signal phy_ctrl : phy_ctrl_t; signal phy_ctrl : phy_ctrl_t;
signal u_tag : user_tag_t; signal u_tag : user_tag_t;
@@ -115,6 +117,7 @@ architecture rtl of sdram_ctrl_top is
alias sd_col_fifo_out is cmd_fifo_dout(CMD_FIFO_DATA_WIDTH-user_tag_t'length-4-mode_word_t'length-1 downto 0); alias sd_col_fifo_out is cmd_fifo_dout(CMD_FIFO_DATA_WIDTH-user_tag_t'length-4-mode_word_t'length-1 downto 0);
begin begin
sdram_clk_out <= sdram_clk0;
--------------------------------- ---------------------------------
part_ctrl.cmd <= cmd_ctrl; part_ctrl.cmd <= cmd_ctrl;
@@ -163,9 +166,9 @@ begin
) )
PORT MAP PORT MAP
( (
rst => sys_rst_in, rst => sdram_rst0,
clk_w => sys_clk_in, clk_w => sys_clk_in,
clk_r => sdram_clk0_in, clk_r => sdram_clk0,
we => cmd_fifo_we, we => cmd_fifo_we,
re => cmd_fifo_re, re => cmd_fifo_re,
fifo_full => cmd_fifo_full, fifo_full => cmd_fifo_full,
@@ -185,8 +188,8 @@ begin
) )
Port map Port map
( (
rst => sys_rst_in, rst => sdram_rst0,
clk => sdram_clk0_in, clk => sdram_clk0,
u_tag_in => sd_tag_fifo_out, u_tag_in => sd_tag_fifo_out,
u_tag_out => u_tag, u_tag_out => u_tag,
phy_ctrl => phy_ctrl, phy_ctrl => phy_ctrl,
@@ -202,16 +205,21 @@ begin
); );
-- DDR phy -- DDR phy
inst_ddr_phy : entity work.ddr_phy inst_sdram_phy : entity work.sdram_phy
Generic map
(
f_sdrclk => f_sdrclk
)
Port map Port map
( (
sys_rst => sys_rst_in, rst => sys_rst_in,
sys_clk0 => sdram_clk0_in, clk => sdram_clk,
sys_clk270 => sdram_clk270_in, clk_fb => sdram_clk_fb,
clk0_out => sdram_clk0,
rst0_out => sdram_rst0,
u_tag_in => u_tag, u_tag_in => u_tag,
u_tag_rd => u_tag_rd, u_tag_rd => u_tag_rd,
u_tag_wr => u_tag_wr, u_tag_wr => u_tag_wr,
read_clk => sdram_clk270_rd_in,
phy_ctrl => phy_ctrl, phy_ctrl => phy_ctrl,
part_ctrl => part_ctrl, part_ctrl => part_ctrl,
sdr_data_req_w => u_data_req_w, sdr_data_req_w => u_data_req_w,
lib/SDRAM/ddr_sdr_v1_5/src/tb_sdram_ctrl_frontend64_wb.vhd
+9 -41
View File
@@ -25,7 +25,6 @@ library IEEE;
use IEEE.STD_LOGIC_1164.ALL; use IEEE.STD_LOGIC_1164.ALL;
use IEEE.numeric_std.ALL; use IEEE.numeric_std.ALL;
use work.fifo_ctrl_pkg.all;
use work.sdram_config.all; use work.sdram_config.all;
use work.sdram_types.all; use work.sdram_types.all;
@@ -34,18 +33,12 @@ end;
architecture struct of tb_sdram_ctrl_frontend64_wb is architecture struct of tb_sdram_ctrl_frontend64_wb is
-- Number of user data words for simulation
constant CLK_PERIOD : time := 10 ns; constant CLK_PERIOD : time := 10 ns;
constant SDCLK_PERIOD : time := 7.5 ns; constant SDCLK_PERIOD : time := 7.5 ns;
constant BURST_LEN : natural := 2; constant BURST_LEN : natural := 2;
signal rst : std_logic := '1';
signal clk : std_logic := '1';
signal sdclk : std_logic := '1'; signal sdclk : std_logic := '1';
signal locked : std_logic; signal sdclk_fb : std_logic;
signal error : std_logic;
signal clk_out : std_logic;
signal clk_fb : std_logic;
signal part_clk_p : std_logic; signal part_clk_p : std_logic;
signal part_clk_n : std_logic; signal part_clk_n : std_logic;
signal part_cke : std_logic; signal part_cke : std_logic;
@@ -59,11 +52,8 @@ architecture struct of tb_sdram_ctrl_frontend64_wb is
signal part_addr : unsigned(DDR_ADDR_WIDTH-1 downto 0) := (others => '0'); signal part_addr : unsigned(DDR_ADDR_WIDTH-1 downto 0) := (others => '0');
signal part_data : unsigned(DDR_DATA_WIDTH-1 downto 0) := (others => '0'); signal part_data : unsigned(DDR_DATA_WIDTH-1 downto 0) := (others => '0');
signal CLK_O : std_logic; signal CLK_O : std_logic := '1';
signal CLK0_O : std_logic; signal RST_O : std_logic := '1';
signal CLK270_O : std_logic;
signal CLK270VAR_O : std_logic;
signal RST_O : std_logic;
signal CYC_O : std_logic := '0'; signal CYC_O : std_logic := '0';
signal STB_O : std_logic := '0'; signal STB_O : std_logic := '0';
signal WE_O : std_logic := '0'; signal WE_O : std_logic := '0';
@@ -119,30 +109,8 @@ begin
end if; end if;
end process; end process;
inst_clockgen : entity work.clockgen sdclk_fb <= part_clk_p after 1 ns;
GENERIC MAP
(
clk_in_freq => 100.0,
clk0_out_phaseshift => 0,
clk1_out_phaseshift => 0
)
PORT MAP
(
-- Clocks and Reset
rst => rst, -- external async reset, low active
clk_in => sdclk, -- system clock (e.g. 100MHz), from board
clk_fb_in => clk_fb, -- feedback clock
clk0_0_out => CLK0_O, -- System clock #0, dcm#0 output 0°
clk0_270_out => CLK270_O, -- System clock #0, dcm#0 output 270°
clk1_0_out => open, -- System clock #1 (e.g. clock for DDR-SDRAM data capture), dcm#1 output 0°
clk1_270_out => CLK270VAR_O, -- System clock #1 (e.g. clock for DDR-SDRAM data capture), dcm#1 output 270°
locked_out => locked, -- DCM locked status
error_out => error
);
clk_fb <= part_clk_p after 1 ns;
CLK_O <= clk;
RST_O <= not locked;
DAT_O <= X"DEADBEEF" & sddat; DAT_O <= X"DEADBEEF" & sddat;
SEL_O <= "0000" & sdsel; SEL_O <= "0000" & sdsel;
@@ -159,9 +127,9 @@ inst_clockgen : entity work.clockgen
( (
RST_I => RST_O, RST_I => RST_O,
CLK_I => CLK_O, CLK_I => CLK_O,
SDRAM_CLK0_I => CLK0_O, SDRAM_CLK_I => sdclk,
SDRAM_CLK270_I => CLK270_O, SDRAM_CLK_FB_I => sdclk_fb,
SDRAM_CLK270VAR_I => CLK270VAR_O,
CYC_I => CYC_O, CYC_I => CYC_O,
STB_I => STB_O, STB_I => STB_O,
SEL_I => SEL_O, SEL_I => SEL_O,
@@ -228,7 +196,7 @@ i_mt46v16m16_1 : entity work.mt46v16m16
CLK_GEN: process CLK_GEN: process
begin begin
wait for CLK_PERIOD/2; wait for CLK_PERIOD/2;
clk <= not clk; CLK_O <= not CLK_O;
end process; end process;
SDCLK_GEN: process SDCLK_GEN: process
@@ -257,7 +225,7 @@ STIMULUS: process
begin begin
wait for 3*CLK_PERIOD; wait for 3*CLK_PERIOD;
rst <= '0'; RST_O <= '0';
wait until RST_O = '0'; wait until RST_O = '0';
-- 8 single cycles -- 8 single cycles
lib/SDRAM/ddr_sdr_v1_5/src/tb_sdram_ctrl_frontend_wb.vhd
+8 -41
View File
@@ -25,7 +25,6 @@ library IEEE;
use IEEE.STD_LOGIC_1164.ALL; use IEEE.STD_LOGIC_1164.ALL;
use IEEE.numeric_std.ALL; use IEEE.numeric_std.ALL;
use work.fifo_ctrl_pkg.all;
use work.sdram_config.all; use work.sdram_config.all;
use work.sdram_types.all; use work.sdram_types.all;
@@ -39,13 +38,8 @@ architecture struct of tb_sdram_ctrl_frontend_wb is
constant SDCLK_PERIOD : time := 8 ns; constant SDCLK_PERIOD : time := 8 ns;
constant BURST_LEN : natural := 2; constant BURST_LEN : natural := 2;
signal rst : std_logic := '1';
signal clk : std_logic := '1';
signal sdclk : std_logic := '1'; signal sdclk : std_logic := '1';
signal locked : std_logic; signal sdclk_fb : std_logic;
signal error : std_logic;
signal clk_out : std_logic;
signal clk_fb : std_logic;
signal part_clk_p : std_logic; signal part_clk_p : std_logic;
signal part_clk_n : std_logic; signal part_clk_n : std_logic;
signal part_cke : std_logic; signal part_cke : std_logic;
@@ -59,11 +53,8 @@ architecture struct of tb_sdram_ctrl_frontend_wb is
signal part_addr : unsigned(DDR_ADDR_WIDTH-1 downto 0) := (others => '0'); signal part_addr : unsigned(DDR_ADDR_WIDTH-1 downto 0) := (others => '0');
signal part_data : unsigned(DDR_DATA_WIDTH-1 downto 0) := (others => '0'); signal part_data : unsigned(DDR_DATA_WIDTH-1 downto 0) := (others => '0');
signal CLK_O : std_logic; signal CLK_O : std_logic := '1';
signal CLK0_O : std_logic; signal RST_O : std_logic := '1';
signal CLK270_O : std_logic;
signal CLK270VAR_O : std_logic;
signal RST_O : std_logic;
signal CYC_O : std_logic := '0'; signal CYC_O : std_logic := '0';
signal STB_O : std_logic := '0'; signal STB_O : std_logic := '0';
signal WE_O : std_logic := '0'; signal WE_O : std_logic := '0';
@@ -116,30 +107,7 @@ begin
end if; end if;
end process; end process;
inst_clockgen : entity work.clockgen sdclk_fb <= part_clk_p after 1 ns;
GENERIC MAP
(
clk_in_freq => 100.0,
clk0_out_phaseshift => 0,
clk1_out_phaseshift => 0
)
PORT MAP
(
-- Clocks and Reset
rst => rst, -- external async reset, low active
clk_in => sdclk, -- system clock (e.g. 100MHz), from board
clk_fb_in => clk_fb, -- feedback clock
clk0_0_out => CLK0_O, -- System clock #0, dcm#0 output 0°
clk0_270_out => CLK270_O, -- System clock #0, dcm#0 output 270°
clk1_0_out => open, -- System clock #1 (e.g. clock for DDR-SDRAM data capture), dcm#1 output 0°
clk1_270_out => CLK270VAR_O, -- System clock #1 (e.g. clock for DDR-SDRAM data capture), dcm#1 output 270°
locked_out => locked, -- DCM locked status
error_out => error
);
clk_fb <= part_clk_p after 1 ns;
RST_O <= not locked;
CLK_O <= clk;
-- DDR SDRAM Controller Core -- DDR SDRAM Controller Core
sdram_ctrl_frontend_wb : entity work.sdram_ctrl_frontend_wb sdram_ctrl_frontend_wb : entity work.sdram_ctrl_frontend_wb
@@ -154,9 +122,8 @@ inst_clockgen : entity work.clockgen
( (
RST_I => RST_O, RST_I => RST_O,
CLK_I => CLK_O, CLK_I => CLK_O,
SDRAM_CLK0_I => CLK0_O, SDRAM_CLK_I => sdclk,
SDRAM_CLK270_I => CLK270_O, SDRAM_CLK_FB_I => sdclk_fb,
SDRAM_CLK270VAR_I => CLK270VAR_O,
CYC_I => CYC_O, CYC_I => CYC_O,
STB_I => STB_O, STB_I => STB_O,
@@ -224,7 +191,7 @@ i_mt46v16m16_1 : entity work.mt46v16m16
CLK_GEN: process CLK_GEN: process
begin begin
wait for CLK_PERIOD/2; wait for CLK_PERIOD/2;
clk <= not clk; CLK_O <= not CLK_O;
end process; end process;
SDCLK_GEN: process SDCLK_GEN: process
@@ -253,7 +220,7 @@ STIMULUS: process
begin begin
wait for 3*CLK_PERIOD; wait for 3*CLK_PERIOD;
rst <= '0'; RST_O <= '0';
wait until RST_O = '0'; wait until RST_O = '0';
-- 8 single cycles -- 8 single cycles