H
Hayami
Hi all,
I'm newbie in vhdl coding style, and I'm becoming crazy to understand
some errors that compiler reports.
I'm trying to write a simple code that receive 8 bit data every clock
and try to find the sequence x"00" x"11" x"22", if data in is found it
write back x"aa" x"bb" then start to monitor data in again.
I'm becoming crazy because the compiles tells me that register DATA
and AABB_FOUND never changes and others are NEVER USED!
please could you help?? Which could be the correct VHDL code?
please find below error reports and vhdl code.
Thank you! Hope to learn more from your replies
Regards,
Hikawa
=========================================================================
* HDL Analysis
*
=========================================================================
Analyzing Entity <arch> (Architecture <behv>).
INFO:Xst:1304 - Contents of register <aabb_found> in unit <arch> never
changes during circuit operation. The register is replaced by logic.
INFO:Xst:1304 - Contents of register <data> in unit <arch> never
changes during circuit operation. The register is replaced by logic.
Entity <arch> analyzed. Unit <arch> generated.
=========================================================================
* HDL Synthesis
*
=========================================================================
Synthesizing Unit <arch>.
Related source file is C:/Programmi/Xilinx/parsec/new.vhd.
WARNING:Xst:646 - Signal <data_in1> is assigned but never used.
WARNING:Xst:646 - Signal <aabb_found> is assigned but never used.
Unit <arch> synthesized.
Here's the simple code:
library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use ieee.std_logic_unsigned.all;
----------------------------------------------
package pak_array is
type x_array is array(0 to 2) of std_logic_vector(7 downto 0);
constant x: x_array :=
(x"00",x"11",x"22");
end pak_array ;
----------------------------------------------
library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.STD_LOGIC_UNSIGNED.ALL;
use work.pak_array.all;
entity arch is
port (
clock: in std_logic;
reset: in std_logic;
data: inout std_logic_vector(7 downto 0) -- bidirectional port
);
end arch;
-----------------------------------------------
architecture behv of arch is
signal data_in1,
data_in2: std_logic_vector(7 downto 0);
constant reset_active: std_logic := '0'; -- active low reset
constant clock_low: std_logic := '0'; -- active low enable
constant data_in: std_logic_vector(15 downto 0):=x"aabb"; -- sequence
signal aabb_found: std_logic;
begin
-- ********************
-- ** SHIFT REGISTER **
-- ********************
SHIFT_reg: process(clock, reset) is
begin
if (reset=reset_active) then
data_in1<=(others=>'Z');data_in2<=(others=>'Z');
elsif (rising_edge(clock)) then
data_in2<=data;
data_in1<=data_in2;
if ((data_in2 & data_in1)=data_in)
then aabb_found<='1';
end if;
end if;
end process;
DATA_OUT: process(clock) is
begin
if (rising_edge(clock)) then
if aabb_found='1' then
for i in x'range loop
data <= x(i);
end loop;
end if;
end if;
end process;
end behv;
I'm newbie in vhdl coding style, and I'm becoming crazy to understand
some errors that compiler reports.
I'm trying to write a simple code that receive 8 bit data every clock
and try to find the sequence x"00" x"11" x"22", if data in is found it
write back x"aa" x"bb" then start to monitor data in again.
I'm becoming crazy because the compiles tells me that register DATA
and AABB_FOUND never changes and others are NEVER USED!
please could you help?? Which could be the correct VHDL code?
please find below error reports and vhdl code.
Thank you! Hope to learn more from your replies
Regards,
Hikawa
=========================================================================
* HDL Analysis
*
=========================================================================
Analyzing Entity <arch> (Architecture <behv>).
INFO:Xst:1304 - Contents of register <aabb_found> in unit <arch> never
changes during circuit operation. The register is replaced by logic.
INFO:Xst:1304 - Contents of register <data> in unit <arch> never
changes during circuit operation. The register is replaced by logic.
Entity <arch> analyzed. Unit <arch> generated.
=========================================================================
* HDL Synthesis
*
=========================================================================
Synthesizing Unit <arch>.
Related source file is C:/Programmi/Xilinx/parsec/new.vhd.
WARNING:Xst:646 - Signal <data_in1> is assigned but never used.
WARNING:Xst:646 - Signal <aabb_found> is assigned but never used.
Unit <arch> synthesized.
Here's the simple code:
library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use ieee.std_logic_unsigned.all;
----------------------------------------------
package pak_array is
type x_array is array(0 to 2) of std_logic_vector(7 downto 0);
constant x: x_array :=
(x"00",x"11",x"22");
end pak_array ;
----------------------------------------------
library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.STD_LOGIC_UNSIGNED.ALL;
use work.pak_array.all;
entity arch is
port (
clock: in std_logic;
reset: in std_logic;
data: inout std_logic_vector(7 downto 0) -- bidirectional port
);
end arch;
-----------------------------------------------
architecture behv of arch is
signal data_in1,
data_in2: std_logic_vector(7 downto 0);
constant reset_active: std_logic := '0'; -- active low reset
constant clock_low: std_logic := '0'; -- active low enable
constant data_in: std_logic_vector(15 downto 0):=x"aabb"; -- sequence
signal aabb_found: std_logic;
begin
-- ********************
-- ** SHIFT REGISTER **
-- ********************
SHIFT_reg: process(clock, reset) is
begin
if (reset=reset_active) then
data_in1<=(others=>'Z');data_in2<=(others=>'Z');
elsif (rising_edge(clock)) then
data_in2<=data;
data_in1<=data_in2;
if ((data_in2 & data_in1)=data_in)
then aabb_found<='1';
end if;
end if;
end process;
DATA_OUT: process(clock) is
begin
if (rising_edge(clock)) then
if aabb_found='1' then
for i in x'range loop
data <= x(i);
end loop;
end if;
end if;
end process;
end behv;