conversion of flip flop

CONVERSION OF FLIP FLOP

Batch:B3 PREPRED BY:- (1)Panchal manthan-140123109008 (2)Panchal jay-140123109007 (3) Patel nikunj-140123109010

Guided by:- Prof. shweta khakhakhar

INTRODUCTION

Basic info. of conversion SR FF to T FF conversion SR FF to JK conversion

CONVERSION OF FLIP FLOPS

The conversion from one type of flip flop to the other (say SS FF to JK FF) needs a systematic approach using the excitation tables and K map simplifications.

Given flip-flop

Flip-flopConversion logic(Combinational circuit)

General model used to convert one type of FF to the other

{Flip-flopData inputs

}Outputs

Required Flip-Flop

Q

Q_

Fig. shows a generalized model for conversion from one flip flop to the other.

As shown in fig. the required flip flop is actually a combination of the given flip flop and a combinational logic circuit using gates.

Such a combinational is called as the flip flop conversion logic.

The input to FF conversion logic are the flip flop data inputs and the outputs of given flip flop.

The conversion logic is designed by combining the excitation tables of both the flip flop i.e. the given FF and the desired FF.

The truth table of the conversion logic has data inputs and Q and Q outputs of the given FF as inputs whereas the inputs of the given FF are the outputs of the truth table.

Then we draw the K map for each output and obtain the simplified expressions.

The conversion logic is then implemented using gates.

_

SR FLIP FLOP TO T FLIP FLOP

Step 1 : Write the truth table :-

Outputs

Inputs T S RPresent state QnNext state Qn+1

0

0

0

0

0

0

0

0

0

0

1

1

1

1

1

1

1

1

×

×

Truth table for SR FF to T FF

Step 2 : Write the K maps and obtain the expressions for S and R :-

Qn

QnT T

××

0

0 0

0

0

0

0

0

11

1

1

1

1

S= T Qn

R= T Qn_

For S output

For R output

(a) K map for S

(b) K map for R

Step 3 : Draw the logic diagram :- The logic diagram is shown in fig.

T flip flop

}Outputs

Conversion from SR flip flop to T flip flop

SR FF

SR FLIP FLOP TO JK FLIP FLOP

Inputs Outputs

J K Present state Qn

Next state Qn+1

S R

0 0 0

0 0 ×

0 1 0 0 0 ×

1 0 0 1 1 0

1 1 0 1 1 0

0 1 1 0 0 1

1 1 1 0 0 1

0 0 1 1 × 0

1 0 1 1 × 0

Step 2 : K maps and simplification :-

Qn

KJ 00 01 11 10

0

1

0 0

0

0

1 1

×

×

_S= J Qn

(a) K map for S

(b) K map for R

For S output

For R output

Qn

KJ 00 01 11 10

×

1

0 1

10 0

0

0

R= K Qn

×

Step 3 : Logic diagram :- The logic diagram of SR to JK flip flop is given in fig.

SR to JK flip flop conversion

CLK

}Outputs

J

K

S Q

R Q_

Conversion logic

JK flip flop

SR FF

www.brighthubengineering.com

BOOK :- J.S.Katre