i have a question about à strange behaviour,
what the difference between
process(i_clk)
variable s_sens_front :STD_LOGIC_VECTOR(1 downto 0):="00";
variable s_cons_prec : STD_LOGIC_VECTOR(9 downto 0):="0000000000";
begin
if rising_edge(i_clk) then
if (s_sens_front = "01" or s_sens_front = "10") then
s_consigne <= i_consigne;
s_cons_prec := i_consigne;
else
s_consigne <= s_cons_prec;
end if;
s_sens_front := s_sens_front(0) & i_sens;
end if;
end process;
and
process(i_clk)
variable s_sens_front :STD_LOGIC_VECTOR(1 downto 0):="00";
variable s_cons_prec : STD_LOGIC_VECTOR(9 downto 0):="0000000000";
begin
if rising_edge(i_clk) then
if (s_sens_front = "01" or s_sens_front = "10") then
s_consigne <= i_consigne;
else
s_consigne <= s_cons_prec;
end if;
s_sens_front := s_sens_front(0) & i_sens;
s_cons_prec := s_consigne;
end if;
end process;
because for me both seem exactly the same... but after i make a test if s_consigne is bigger than an other signal, and the first work correctly, but not the second version... with no more change.
the code around is
process(i_clk)
variable s_H_prec :STD_LOGIC;
begin
if rising_edge(i_clk) then
if (i_triangle >= s_consigne) then
s_H <='0';
else
s_H <= '1';
end if;
s_H_prec := S_H;
end if;
end process;
the i_triangle and i_sens was made here
process(i_clk)
variable s_triangle : unsigned (9 downto 0):="1000000000";
variable s_triangle_temp : unsigned (9 downto 0):="1000000000";
variable s_sens_temp : std_logic;
variable s_ratio_max : unsigned (9 downto 0):="1111111111";
variable s_sens : std_logic; -- Signal qui indique si le triangle doit monter ou descendre
begin
if rising_edge(i_clk) then
if i_reset_n = '0' then -- quand reset on remet tout au valeur du début
s_sens := i_sens;
s_triangle := i_init;--valeur du triangle qui va évolué
s_triangle_temp := i_init;--valeur du triangle du début mémorisé
s_sens_temp := i_sens;--valeur du sens mémorisé
else
if (s_triangle_temp = s_triangle and s_sens = s_sens_temp) then -- si on a fait une période compléte
-- on donne la nouvelle valeur si elle existe
if (i_sens = '1') then
s_triangle := i_init + 1;
else
s_triangle := i_init -1;
end if;
s_sens := i_sens;
s_triangle_temp := i_init;--valeur du triangle du début mémorisé
s_sens_temp := i_sens;--valeur du sens mémorisé
else
if s_triangle >= s_ratio_max then --si le compteur est plus grand ou égal au max alors
s_sens := '0'; -- on indique qu'il faut décompter
s_triangle := s_ratio_max -1; -- on va à la valeur max -1
elsif s_triangle = "0000000000" then
s_sens := '1';
s_triangle := "0000000001";
s_ratio_max := i_ratio_max;-- on ne le prend que quand on est au minimum
elsif s_sens = '1' then
s_triangle := s_triangle + 1;
else
s_triangle := s_triangle - 1;
end if;
end if;
end if;
o_sens <= s_sens;
o_triangle <= s_triangle;
end if;
end process;
i_init and i_sens are variable i change with a vjtag and a GUI
and the output of S_H go here
process(i_clk)
variable s_compteurH: UNSIGNED (9 downto 0) := "0000000000";
variable s_compteurL: UNSIGNED (9 downto 0) := "0000000000";
variable S_H : STD_LOGIC;
variable S_L : STD_LOGIC;
begin
if rising_edge(i_clk) then
if (i_reset_n = '0') then
O_L <= '0';
O_H <= '0';
else
if (i_h = '0') then
S_H := '0';
s_compteurH := "0000000000";
if (s_compteurL >= i_retard) then
S_L := '1';
else
s_compteurL := s_compteurL +1;
end if;
else
S_L := '0';
s_compteurL := "0000000000";
if (s_compteurH >= i_retard) then
S_H := '1';
else
s_compteurH := s_compteurH +1 ;
end if;
end if;
end if;
o_H <= S_H;
o_L <= S_L;
end if;
end process;
and i see the O_H and O_L on oscilloscope. and in the two case the behaviour was different, and know i understand, thanks Staszek The thing is that in process only the last assignment to signal really happens, and new value will be there after the process completes. It is different to variables, where assignment happens immediately. So in s_cons_prec := s_consigne; s_consigne still has old value.
Well, this is not very well asked question, there is no Minimal Complete Verifable Example, but I guess, you don't know how signals works. The thing is that in process only the last assignment to signal really happens, and new value will be there after the process completes. It is different to variables, where assignment happens immediately. So in s_cons_prec := s_consigne; s_consigne still has old value.