 Hello everyone, welcome to this session on flip flop analysis. Today we are going to analyze D flip flop. We will understand the different parts of this analysis of D flip flops. So, at the end of this session you will be able to derive the characteristic equation of D flip flop, discuss the state table and state diagram of D flip flop and derive the excitation table for the D flip flop. So, let us go through one by one. So, let us first revisit the function table of your D flip flop. So, you can pause the video and please write down the characteristic table of your D flip flop. So, this table specifies the functional behavior of the flip flop in the tabular form. So, characteristic table lists the next state q t plus 1 for each combination of your D inputs and the present state. So, D flip flop is having two states a reset state and set state. So, in the reset state you apply D is equal to 0 and in set state you apply D is equal to 1. So, in between the clock edges the previous values will be maintained. So, here on the slide you will see that two symbols are shown for the D flip flops. First is positive is triggered D flip flop, second is the negative is triggered D flip flop. Now, let us derive the first characteristic equation of your D flip flop. So, what is the characteristic equation? So, characteristic equation is a Boolean expression which we are going to derive from the characteristic table. So, this expression specifies the flip flops next state q t plus 1 as a function of its current state q t and input signal D. So, this is the characteristic table we have derived from our functional table of D flip flop. So, here q t plus 1 is listed as a function of D and q t. D is the input q t is the present state whereas, q t plus 1 is the next state of your flip flop. So, when D is equal to 0 and q t is equal to 0 q t plus 1 is 1 D is 0 present state is 1 next state will be 0. D is 1 present state is 0 next state will be 1 and the last combination D input is 1 present state is 1 next state will remain 1. Now, let us use this characteristic table with the help of K map we will derive the characteristic equation for our D flip flop. So, here inputs are D and q t and the expression we will get from this K map with the help of this K map is q t plus 1 is equal to D. So, this is the characteristic equation for our D flip flop. Now, let us understand what is a state table. So, state table shows you the transition of flip flop from present state to the next state for varied input combinations. So, with the present state and the flip flop input the next state of the flip flop can be derived from the characteristic table. So, here this table you will see that you have present state and next state columns. So, next state columns again you have two sub columns D is equal to 0 and D is equal to 1. So, you can use this characteristic table for deriving the state table for this D flip flop. So, you can consider the q q t which is present state for your reference ok. So, present state is 0 D is 0 what is next state 0. Next present state is 1 D is 0 present state 1 D is 0 the next is next state is 0. Next combination third row of characteristic table gives you more information about the your state table. So, if q is present state is 0 and D is 1 then next state will change to 1 ok. So, present state is 0 D is 1 next state will change to 1. Last row present state 1 and D is 1 then your next state will be 1 present state 1 D is 1 next state will be 1. So, this is how you can derive the state table for your D flip flop. Now, let us go to the next point state diagram for your D flip flop. For state diagram of your D flip flop you can use or refer the state table which we have derived in the last slide. So, state diagram is a graph with nodes and directed edges connecting all these nodes. So, nodes are labeled with the states ok. So, these nodes are labeled here with the states. So, D flip flop can be either in one of these two states 0 or 1 ok. So, nodes are labeled with the states of the flip flop and the directed edges are labeled with the flip flop input ok. So, these are the directed edges and these are labeled with here flip flop inputs. So, this these flip flop inputs causes the transition from one state to another state ok. So, here let us understand how to draw this state diagram for your D flip flop. So, you can use this state table for this. So, present state is 0 and if D is D 0 your next state will be 0. If the present state is 0 if the D is 1 then next state will be 1. Now, present state is 1 D is 1 next state will remain 1. Again if present state is 1 and D is 0 then your next state will change this to 0. So, this state diagram shows you the transition between different state caused by your flip flop inputs. Now, let us go to the excitation table. So, excitation table provides the excitations required to change a flip flop from one state to next state. So, flip flop input D is presented as a dependent function of state transition. So, here D will you will see D in the last column output column and on the input side you will see the present state and next state. So, if you want present state to next state you can apply the respective D input. For example, present state is 0 if you want next state 0 you can apply 0 to D input. If the present state 0 next state if you want 1 then apply 1 to D input. If the present state is 1 if you want next state as a 0 then apply 0 to D input and the last case if the present state is 1 and if you still want to be remain in the same state 1 then apply 1 to your D input. So, this state diagram also gives you this excitation information. So, 0 to 0 state your D is 0, 0 to 1 state D should be 1, 1 to 1 state D should be 1 and from 1 to 0 state D should be 0. So, this shows you how to derive the excitation table required for your D flip flop. So, a particular state transition predicts the flip flop input. So, using these state diagrams you can actually predict the flip flop input required for that particular state transition. So, normally excitation tables are used in the design and synthesis of your synchronous sequential machines. For example, counters, finite state machines, etc. These are the references you can go through for further learning. Thank you.