现在在调fpga控制dds的程序，wclk，8位data，freq_ud的时序都没问题，但就是出不来波形，请高手指点
程序如下
--0x40000000
library ieee;
use ieee.std_logic_1164.all;
use ieee.std_logic_unsigned.all;
entity dds_source is
port(clk :in std_logic;
fpga_reset :in std_logic;
B_dir :out std_logic_vector(7 downto 0);
B_oe :out std_logic_vector(7 downto 0);
data :out std_logic_vector(7 downto 0);
wclk :out std_logic;
dds_reset :out std_logic;
freq_ud :out std_logic
);
end dds_source;
architecture behavior of dds_source is
signal clkdiv :std_logic:='1';
begin
B_dir <= "00000000";
B_oe <= "00000000";
process(clk)
variable clkcnt :std_logic_vector(7 downto 0);
begin
if clk'event and clk='1' then
if clkcnt="00000001" then
clkcnt := (others=>'0');
clkdiv <= not clkdiv;
else
clkcnt := clkcnt+1;
end if;
end if;
end process;
process(clkdiv)
variable count :integer range 0 to 15;
variable cnt :integer range 0 to 5;
begin
if fpga_reset='0' then
wclk <= '0';
freq_ud <= '0';
count := 0;
cnt := 0;
elsif clkdiv'event and clkdiv='0' then
case count is
when 0 =>
data <= "00000000";
if cnt=2 then
wclk <= '1';
cnt := cnt+1;
elsif cnt=4 then
wclk <= '0';
cnt := cnt+1;
elsif cnt=5 then
count := 1;
cnt := 0;
else
cnt := cnt+1;
end if;
when 1 =>
data <= "01000000";
if cnt=2 then
wclk <= '1';
cnt := cnt+1;
elsif cnt=4 then
wclk <= '0';
cnt := cnt+1;
elsif cnt=5 then
count := 2;
cnt := 0;
else
cnt := cnt+1;
end if;
when 2 =>
data <= "00100000";
if cnt=2 then
wclk <= '1';
cnt := cnt+1;
elsif cnt=4 then
wclk <= '0';
cnt := cnt+1;
elsif cnt=5 then
count := 3;
cnt := 0;
else
cnt := cnt+1;
end if;
when 3 =>
data <= "00010000";
if cnt=2 then
wclk <= '1';
cnt := cnt+1;
elsif cnt=4 then
wclk <= '0';
cnt := cnt+1;
elsif cnt=5 then
count := 4;
cnt := 0;
else
cnt := cnt+1;
end if;
when 4 =>
data <= "00001000";
if cnt=2 then
wclk <= '1';
cnt := cnt+1;
elsif cnt=4 then
wclk <= '0';
cnt := cnt+1;
elsif cnt=5 then
count := 5;
cnt := 0;
else
cnt := cnt+1;
end if;
when 5 =>
data <="00000000";
if cnt=5 then
count := 6;
cnt := 0;
freq_ud <= '0';
else
cnt := cnt+1;
freq_ud <= '1';
end if;
when 6 =>
dds_reset <= '1';
if cnt=5 then
count := 0;
cnt := 0;
else
cnt := cnt+1;
end if;
when others =>
count :=0;
end case;
end if;
end process;
end behavior;
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