1 A Sequential Parity Checker Parity Checker X Z Clock(P) (Data Input) Odd Parity – Total number of 1 bits is odd. Even Parity – Total number of 1 bits is even. 0000000 1 0110110 0 1010101 1 7 data bits parity bit Example: Odd parity This is a simple example of a sequential network with one input plus clock. ned for serial data input ta enters the network sequentially,one bit at a time. dd parity checker, Z = 1 (at a given time) if the total numbe eceived is odd.
14
Embed
1 A Sequential Parity Checker Parity Checker X Z Clock(P) (Data Input) Odd Parity – Total number of 1 bits is odd. Even Parity – Total number of 1 bits.
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
1
A Sequential Parity Checker
Parity Checker
X Z
Clock(P)
(Data Input)
Odd Parity – Total number of 1 bits is odd.Even Parity – Total number of 1 bits is even.
0000000 10110110 01010101 1
7 data bits parity bit
Example: Odd parity
This is a simple example of asequential network with one input plus clock.
Designed for serial data input-- data enters the network sequentially,one bit at a time.
For an odd parity checker, Z = 1 (at a given time) if the total numberof 1’s received is odd.
2
A Sequential Parity Checker
State Graph
Network Timing Diagram
State Table State Table for T-FF implementation
State Encoding:
S0 Q = 0
S1 Q = 1
3
Moore Sequential Network
-a sequential network whoseoutput is a function of the present state only.
A “false” value arises becausethe network has assumed a newstate but the old input associatedwith the previous state is stillpresent.
5
1. Determine the FF input equations and the output equations from the network.2. Derive the next-state equation for each FF from its input equations using the characteristic equation D FF Q+ = D
T-FF Q+ = T Q
SR-FF Q+ = S + R’Q JK-FF Q+ = JQ’ + K’Q
3. Plot a next state map for each FF4. Combine these maps to form the state table.
Deriving the State Table
6
The FF input eqns. and output eqn. areJA = X KA = XB’ Z = B
JB = X KB = X A’
The next state eqns. for the FF’s areA+ = JAA’ + K’AA = XA’ + (X’ + B)A
Combinational subnetworkrealizes the n outputfunctions and the k next state functions, which serveas inputs to the D=FF’s.All FF’s change state synchronous with clock pulse.After FF’s change state thenew FF outputs are fed back into the combinationalsubnetwork awaiting the nextclock pulse.
12
Moore Sequential Network -- General
Model D-FF’s
-Similar to Mealy.In the combinationalsubnetwork the output section is drawn separately from theinput section. (Output is onlya function of the present state.)
13
State Table with Multiple Inputs and Outputs
Let X=0 rep. the input combination X1X2= 00, X=1 rep. X1X2= 01, etc.
Let Z=0 rep. the output combination Z1Z2= 00, Z=1 rep. Z1Z2= 01, etc.
Obtain the following table in terms of a single input variable X and a singleoutput variable Z.
(S0 , 1) = S2 (S2 , 3) = S1 Next State functions … S+ = (S,X)
(S0 , 1) = 2 (S2 , 3) = 1 Output function …….. Z = (S,X)