ECE-362 Microprocessor Systems and Interfacing
1

Introduction to VHDL
Introductory Concepts

Hardware Description Languages (HDLs) q In the following ‘C’ program Yout is assigned the value of in0 or

In1 depending on the value of Select :-

if (select == 0) yOut := in0 else yOut := in1;
? What hardware structure would perform an equivalent operation

?

Hardware Description Languages (HDLs) q In the following ‘C’ program Yout is assigned the value of in0 or

In1 depending on the value of Select :-

if (select == 0) yOut := in0 else yOut := in1;
? What hardware structure would perform an equivalent operation

? In0 0 yOut

In1 1 select Hardware Description Languages (HDLs) q In the following ‘C’ program Yout is assigned the value of in0 or

In1 depending on the value of Select :-

if (select == 0) yOut := in0 else yOut := in1;
? What hardware structure would perform an equivalent operation

? In0 0 yOut

In1 1 select = 0

Hardware Description Languages (HDLs) q In the following ‘C’ program Yout is assigned the value of in0 or

In1 depending on the value of Select :-

if (select == 0) yOut := in0 else yOut := in1;
? What hardware structure would perform an equivalent operation

? In0 0 yOut

In1 1 select = 0

Hardware Description Languages (HDLs) q In the following ‘C’ program Yout is assigned the value of in0 or

In1 depending on the value of Select :-

if (select == 0) yOut := in0 else yOut := in1;
? What hardware structure would perform an equivalent operation

? In0 0 yOut

In1 1 select Hardware Description Languages (HDLs) q In the following ‘C’ program Yout is assigned the value of in0 or

In1 depending on the value of Select :-

if (select == 0) yOut := in0 else yOut := in1;
? What hardware structure would perform an equivalent operation

? In0 0 yOut

In1 1 select = 1

Hardware Description Languages (HDLs) q In the following ‘C’ program Yout is assigned the value of in0 or

In1 depending on the value of Select :-

if (select == 0) yOut := in0 else yOut := in1;
? What hardware structure would perform an equivalent operation

? In0 0 yOut

In1 1 select = 1

Exercise (1)
? Write a section of code, in a programming language of your choice, that models the behaviour of the following hardware block diagram :-

a b c d

Add a a+b b Divide a a/b b

Multiplex 0 out 1

z

sel

Exercise (1)
? Write a section of code, in a programming language of your choice, that models the behaviour of the following hardware block diagram :-

a b c d

Add a a+b b Divide a a/b b

Multiplex 0 out 1

z

if sel = ‘0’ { } else { }

sel

Exercise (1)
? Write a section of code, in a programming language of your choice, that models the behaviour of the following hardware block diagram :-

a b c d

Add a a+b b Divide a a/b b

Multiplex 0 out 1

z

if sel = ‘0’ { z = a + b; } else { }

sel

Exercise (1)
? Write a section of code, in a programming language of your choice, that models the behaviour of the following hardware block diagram :-

a b c d

Add a a+b b Divide a a/b b

Multiplex 0 out 1

z

if sel = ‘0’ { z = a + b; } else { z = c/d; }

sel

VHDL Example
Entity F
1 2 3 4 5 6 7 8 ENTITY previous IS PORT ( a : IN BIT_VECTOR (2 DOWNTO 0); b : IN BIT_VECTOR (2 DOWNTO 0); c : IN BIT_VECTOR (2 DOWNTO 0); d : IN BIT_VECTOR (2 DOWNTO 0); sel: IN BIT; z : OUT BIT_VECTOR (2 DOWNTO 0)); END previous;

Architecture F 1

2 3 4 5 6 7 8 9 10 11

ARCHITECTURE behavioural OF previous IS BEGIN PROCESS (a, b, c, d, sel) BEGIN IF sel = ‘0’ THEN z