The plus (+) indicates a more advanced problem and the asterisk (*) indicates that a solut...

The plus (+) indicates a more advanced problem and the asterisk (*) indicates that a solution is available on the Companion Website for the text.

+Repeat Problem, designing a sequential circuit that transforms an NRZI message into a normal message. The mapping for such a circuit is as follows:

(a) If a change from 0 to 1 or from 1 to 0 occurs between adjacent bits in the NRZI message, then the message bit is a 0.

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(b) If no change occurs between adjacent bits in the NRZI message, then the message bit is a 1.

Problem

In many communication and networking systems, the signal transmitted on the communication line uses a non-return-to-zero(NRZ) format. USB uses as pecific version referred to as non-return-to-zero inverted (NRZI). A circuit that converts any message sequence of 0s and 1s to a sequence in the NRZI format is to be designed. The mapping for such a circuit is as follows:

(a) If the message bit is a 0, then the NRZI format message contains an immediate change from 1 to 0 or from 0 to 1, depending on the current NRZI value.

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(b) If the message bit is a 1, then the NRZI format message remains fixed at0 or 1, depending on the current NRZI value.

This transformation is illustrated by the following example, which assumes that the initial value of the NRZI message is 1:

Message:10001110011010

NRZI Message: 10100001000110

(a) Find the Mealy model state diagram for the circuit.

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(b) Find the state table for the circuit and make a state assignment.

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(c) Find an implementation of the circuit using D flip-flops and logic gates.