Digital Electronics : Generation of state diagram form a timing chart

1. GENERATION OF STATE
DIAGRAM FROM A
TIMING CHART

2.  INTRODUCTION OF STATE DIAGRAM :
 A state diagram is a type
of diagram used in computer
science and related fields to describe
the behavior of systems. State diagrams
require that the system described is
composed of a finite number of states;
sometimes, this is indeed the case,
while at other times this is a
reasonable abstraction.
 Many forms of state diagrams exist,
which differ slightly and have
different semantics.

3.  WHAT IS A STATE DIAGRAM ?
 A state diagram shows the behavior of
classes in response to external stimuli.
Specifically a state diagram describes the
behavior of a single object in response to a
series of events in a system.
 Sometimes it's also known as a Harel state
chart or a state machine diagram. This UML
diagram models the dynamic flow of control
from state to state of a particular object
within a system.

4.  Basic State Diagram Symbols and Notations
 States
States represent situations during the life of an
object. You can easily illustrate a state in
SmartDraw by using a rectangle with rounded
corners.
 Transition
A solid arrow represents the path between
different states of an object. Label the
transition with the event that triggered it and
the action that results from it. A state can have
a transition that points back to itself.

5.  HOW TO DRAW A STATE DIAGRAM ?
 Before you begin your drawing find the initial
and final state of the object in question.
 Next, think of the states the object might
undergo. For example, in e-commerce a
product will have a release or available date, a
sold out state, a restocked state, placed in cart
state, a saved on wish list state, a purchased
state, and so on.
 Certain transitions will not be applicable when
an object is in a particular state, for example a
product can be in a purchased state or a saved
in cart state if its previous state is sold out.

6.  INTRODUCTION OF TIMEING CHART
 A chart showing the standard times in various parts of the world with reference to a
specified time at a specified place.

7.  What is the Difference between a State Diagram and a
TIMING CHART ?
 A flowchart illustrates processes that are executed in the system that change the state
of objects. A state diagram shows the actual changes in state, not the processes or
commands that created those changes.
STATE DIAGRAM TIMING CHART

8.  GENERATION OF A STATE DIAGRAM FROM A
TIMING CHART
 Many times, digital system use a timing chart o describe its function. We can use this
timing chart to create the state diagram. Once the state diagram is obtained we can
designed the system as discussed earlier.
 Let us consider the timing chart as shown in figure. As shown in the figure , the
sequential circuit has two inputs A &b along with clock signal and one output Z.
TIMING CHART

9.  It can be observed that
 Input changes occurs on the negative transitions of
clock and both the inputs are asserted for exactly
one lock period.
 System does nothing as long as A and B inputs are
simultaneously zero.
 Output assertion begins at positive transition of
clock.
 If B is asserted, the system goes to state C and
generates an output at positive clock transition. It
then goes back o state A.
 When A is asserted, but b is not asserted, the
system goes to state C, and generates a second
output before returning to state A.
𝐵
1
𝑐
1
𝐴
1
A=1
B=0 B=1
A=B=0