WYV60

Contemplation of Synchronous Gray Code Counter and its Variants using Reversible Logic Gates

Saligram,R.

Information & Communication Technologies (ICT), 2013 IEEE Conference on

DOI:10.1109/CICT.2013.6558177

Publication Year:2013 Page(s): 661 - 665

Project Title :Contemplation of Synchronous Gray Code Counter and its Variants using Reversible Logic Gates

Domain:VLSI

Reference:IEEE

Publish Year:11-12 April 2013 Page(s): 661 – 665

D.O.I:10.1109/CICT.2013.6558177

Software Tool :XILINX

Language : Verilog HDL

Developed By:Wine Yard Technologies, Hyderabad

Contemplation of Synchronous Gray Code Counter and its Variants using Reversible Logic Gates

Abstract:

A Gray Code is an encoding of integers as sequences of bits with the property that the representations of adjacent integers differ in exactly one binary position. Gray Codes have many practical applications that go beyond research interests. There are different types of gray codes: Binary reflected, Maximum Gap, Balanced, Antipodal and Non Composite to name a few. On the other hand Reversible logic has received great attention due to their ability to reduce the power dissipation--an important aspect of low power circuit design. Other applications include Optical information processing, DNA computing, bio informatics, quantum computation and nanotechnology. Counters have a primary function of producing a specified output sequence and are thus sometimes referred to as pattern generators. This paper proposes design of different gray code counters using reversible logic gates, to draw comparative conclusions upon their performance.

Keywords- Gray Code, Binary Reflected Gray Code, Uniform Balanced Gray Code, Antipodal Gray Code, Reversible logic circuits, Quantum Computation.

Existing method:

Today, Gray codes are widely used to facilitateerror correctionin digital communications such asdigital terrestrial televisionand somecable TVsystems.AGray codeis a code assigning to each of a contiguous set ofintegers, or to each member of a circular list, a word of symbols such that each two adjacent code words differ by one symbol. These codes are also known assingle-distance codes, reflecting theHamming distanceof 1 between adjacent codes. There can be more than one Gray code for a given word length, but the term was first applied to a particularbinarycode for the non-negative integers, thebinary-reflected Gray code, orBRGC.A typical use of Gray code counters is building a FIFO (first-in, first-out) data buffer that has read and write ports that exist in different clock domains. The input and output counters inside such a dual-port FIFO are often stored using Gray code to prevent invalid transient states from being captured when the count crosses clock domains.

Theupdated read and write pointers need to be passed between clock domains when they change, to be able to track FIFO empty and full status in each domain. Each bit of the pointers is sampled non-deterministically for this clock domain transfer. So for each bit, either the old value or the new value is propagated. Therefore, if more than one bit in the multi-bit pointer is changing at the sampling point, a "wrong" binary value (neither new nor old) can be propagated. By guaranteeing only one bit can be changing, Gray codes guarantee that the only possible sampled values are the new or old multi-bit value. Typically Gray codes of power-of-two length are used.

The design of gray code counters such as Gray Code, Binary Reflected Gray Code, Uniform Balanced Gray Code, Antipodal Gray Codes aredesigned by using conventional gates like AND, NOT, XOR etc. using the Boolean expressions.

Proposed method:

The development in the field of nanometer technology leads to minimize the power consumption of logic circuits. Reversible logic design has been one of the promising technologies gaining greater interest due to less dissipation of heat and low power consumption. In the digital design, thegray code counters are widely used process. So, the reversible logic gates and reversible circuits for realizing gray code counters like as Gray Code, Binary Reflected Gray Code, Uniform Balanced Gray Code, Antipodal Gray codes using reversible logic gates is proposed.Designing of reversible logic circuit is challenging task, since not enough number of gates are available for design. Reversible processor design needs its building blocks should be reversible in this view the designing of reversible code converters became essential one. In the digital domain, data or information is represented by a combination of 0’s and 1’s. A code is basically the pattern of these 0’s and 1’s used to represent the data. Gray Code counters are a class of sequential digital circuits that are used to counting operation.The proposed design leads to the reduction of power consumption compared with conventional logic circuits.

Applications:

  1. Digital systems designing
  2. Digital signal processing
  3. Communication protocols
  4. Microprocessors
  5. Cryptography applications

Advantageous:

  1. Area Efficient circuits.
  2. Low power Circuits

Conclusion:

Gray codes play a major role in research span from signal encoding and decoding (W digital image processing, data compress processor allocation in the hyper cube, order on shelves, information storage and retrieve robotics and mechanical encoding to solving Towers of Hanoi and Chinese rings.Gray Code counters are non-glitch counters changes. Gray code counters can be used FIFO's address pointers. They reduce the compared to the normal counters. They also used data path synchronization. They are widely error correction in digital communication terrestrial television and some cable TV systems

Circuit Diagram:

Screen shots:

BRGCC:

AGCC:

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