EXP-1: SIMULATION OF VHDL CODE FOR COMBINATIONAL CIRCUIT (POS)

AIM:
        To optimize a 4 variable combinational function POS(Y=(A+B+C').(B'+C'+D).(A+C+D)), describe it in VHDL code and simulate it.

APPARATUS REQUIRED:
         Xilinx V14.7 Software

PRODUCT OF SUM(POS):
          Y=(A+B+C') . (B'+C'+D) . (A+C+D)

LOGIC DIAGRAMS:

TRUTH TABLE:

FLOW CHART:

PROGRAMS:

library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.STD_LOGIC_ARITH.ALL;
use IEEE.STD_LOGIC_UNSIGNED.ALL;

entity Productofsum_m is
    Port ( a : in  STD_LOGIC;
           b : in  STD_LOGIC;
           c : in  STD_LOGIC;
           d : in  STD_LOGIC;
           y : out  STD_LOGIC);
end Productofsum_m;

architecture Behavioral of Productofsum_m is
begin
process (a,b,c,d)
begin
y <= (a or b or (not c)) and ((not b) or (not c) or d) and (a or c or d);
end process;
end Behavioral;

SIMULATION OUTPUT:

PROCEDURE:
Step1: Open xilinx software > go to file > new project > create source file name> select specific folder> next >  select proper project settings> we use spartan 3E trainer kit.

Step2: next > finish > go to project > new source > select VHDL module > create file name> next > select input and output > next > finish> write program > if done write programs > click synthesis > right click> run.

Step3: if completed successfully > go to simulation > click source file > right click > new source > select VHDL test bench > create simulation file name > next > select source file > next > finish.

Step4: select simulation file > Isim simulator > click behavioral check syntax > right click > run > if successfully completed. click simulation behavioral > right click > run > wait few seconds > will open new tap.

Step5: click object name > right click > select force clock >

Step6: set all input force clock > if change only period for all inputs >
            if use 2input (1st input period 4us and 2nd input period 2us)
            if use 3input (1st input period 8us , 2nd input period 4us and 3rd input period 2us)
            if use 4input (1st input period 16us , 2nd input period 8us , 3rd input period 4us and 4th input period 2us)

Step7: click Run All > click zoom to full view > check simulation output in this screen
         
 NOTE: if you want image file > click print screen  > open MS paint > cnt +v > save
           if you want PDF file > file > print > select doPDF printer > create pdf file name + quality> ok