process sentence in synthesis

[Jluis]

hi vhdl group..!!!

on the process sentence what do I have to put FOR SYNTHESIS?
FOR EXAMPLE

PORT(
clk: IN std_logic; --CLOCK
wIR: IN std_logic; --CONTROL SIGNAL
datainIR: IN std_logic_vector(21 DOWNTO 0);
Aout,Bout: OUT std_logic_vector(2 DOWNTO 0)
);

ARCHITECTURE archinst OF inst IS
BEGIN
PROCESS(clk)
BEGIN
OR
ARCHITECTURE archinst OF inst IS
BEGIN
PROCESS(clk, wIR, datainIR)
BEGIN

ON THIS EXAMPLE i HAVE TO PUT ALL THE INPUTS PORT OR WHAT?

THANKS IN ADVANCE.

JLuis

 

[Nicolas Matringe]

Jluis a écrit:

hi vhdl group..!!!
Hi

[...]


ARCHITECTURE archinst OF inst IS
BEGIN
PROCESS(clk)
BEGIN
OR
ARCHITECTURE archinst OF inst IS
BEGIN
PROCESS(clk, wIR, datainIR)
BEGIN

ON THIS EXAMPLE i HAVE TO PUT ALL THE INPUTS PORT OR WHAT?

(please don't shout, we're not deaf)
It all depends on what you do in your process. Usually, clocked
processes need only the clock (and the reset when it is asynchronous)
put in the sensitivity list.

 

[Ralf Hildebrandt]

Jluis wrote:

PORT(
clk: IN std_logic; --CLOCK
wIR: IN std_logic; --CONTROL SIGNAL
datainIR: IN std_logic_vector(21 DOWNTO 0);
Aout,Bout: OUT std_logic_vector(2 DOWNTO 0)
);

ARCHITECTURE archinst OF inst IS
BEGIN
PROCESS(clk)
BEGIN
OR
ARCHITECTURE archinst OF inst IS
BEGIN
PROCESS(clk, wIR, datainIR)
BEGIN

ON THIS EXAMPLE i HAVE TO PUT ALL THE INPUTS PORT OR WHAT?

In the sensitivity list of a process (the signals in parenthesis) all
signals have to be put in, that are read in this process. It does not
matter if these are input signals or internal signals.


Exception: If you write a syncronous process (flipflop), all asyncronous
signals and the clock-signal have to be put into the sensitivity list.
Example:

process(reset,set,clock)
begin
if (set='1') then
out_signal<='1';
elsif (reset='1') then
out_signal<='0';
elsif rising_edge(clock) then
out_signal<=(in_signal1 AND in_signal2) XOR in_signal3;
end if;
end process;

Note: in_signal1, in_signal2 and in_signal3 do not appear in the
sensitivity list (although being read), because they are read only at
rising_edge(clock). Therefore it is useless to activate the process, if
in_signal1, in_signal2 or in_signal3 changes.



For all other processes (that model combinational logic or latches) the
1st statement holds: "Put all signals in the sensitivity list, that are
being read in the process."
Example - comb. logic:

process(in_signal1,in_signal2,in_signal3)
begin
out_signal<=(in_signal1 AND in_signal2) XOR in_signal3;
end process;


Example - latch:

process(latch_enable,in_signal1,in_signal2,in_signal3)
begin
if latch_enable='1') then
out_signal<=(in_signal1 AND in_signal2) XOR in_signal3;
end if;
end process;


Ralf

 

[Riyaz]

This depends on which signals the process is reading. You only supply those
inputs to the process statement that the process is 'sensitive' to, i.e.
those signals that are used in the process.