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Multiple paths through a grey code

IP.com Disclosure Number: IPCOM000214954D
Publication Date: 2012-Feb-15
Document File: 3 page(s) / 60K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method to provide multiple paths through a grey code. The method implements alternate, but still grey, paths through a grey code to allow traversal of the code in less time while maintaining the single-bit change nature of the grey code. This allows for proper operation of circuitry controlled by the grey coded bits.

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Avago Technologies                                                        

Multiple paths through a grey code

Abstract

Disclosed is a method to provide multiple paths through a grey code. The method implements alternate, but still grey, paths through a grey code to allow traversal of the code in less time while maintaining the single-bit change nature of the grey code. This allows for proper operation of circuitry controlled by the grey coded bits.

Description

A.           Prior solutions and their disadvantages

A grey code is defined such that a transition from any state to the next state (and by extension, the previous state) involves the change of only a single-bit of the code. While this often complicates the use/decoding of the code, it has many benefits in asynchronous design; the primary being that glitches caused by skew in the delay of different bits is eliminated, therefore having no effect on the operation of subsequent circuits. This usually requires sequential or single-stepped transitions through a grey code. In some applications, this requirement can negatively affect system performance.

Any transition in a Karnaugh map to a vertically or horizontally adjacent (but not diagonal) cell is a single-bit change and consistent with grey encoding. This allows for the definition of many different encodings that are grey as well as many paths through any grey code that retain the grey nature. Grey codes can be designed with alternate, but still grey, paths that allow rapid traversal while maintaining the grey requirements of the associated circuitry; even binary searches can be approximated, but not totally achieved.

In addition, grey codes are most often traversed sequentially, which is slow. Other traversals comprise the benefits of single-bit changes. In some circuits and systems neither of these is a desirable alternative.

B.           Problems solved by the invention

·         Requirement of sequential or single-stepped transitions through a grey code can negatively affect system per...