Binary-to-Gray FIFO Pointer Circuit for Burst Synchronization
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Solution Overview
Problem
Existing binary-to-Gray conversion techniques in FIFO memories fail to maintain a unitary Hamming distance between consecutive Gray encoded values during burst mode operations, leading to errors in synchronization across clock domains.
Innovation Solution
A Binary-to-Gray conversion circuit that includes a prediction circuit generating binary candidate values with a Hamming distance of one from the target Gray encoded value, an arbiter selecting the appropriate candidate based on input signals, and an encoder producing the final Gray encoded output, ensuring consistent signal transitions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If burst mode writing is implemented to increase productivity, then the write speed is improved, but the Hamming distance between consecutive Gray encoded values becomes greater than one, causing synchronization errors
Solution Approach 1:
The patent applies preliminary action by pre-calculating intermediate Gray encoded values before the final burst write operation. The conversion circuit generates a sequence of intermediate Gray codes that bridge the gap between the initial and final pointer values, ensuring that each transition maintains a Hamming distance of one. This preparatory generation of intermediate values prevents synchronization errors while enabling burst mode operation.
Solution Approach 2:
The patent uses an intermediary approach by introducing intermediate Gray encoded values as mediators between the initial and final pointer states. Instead of directly transitioning from one pointer value to another in burst mode, the circuit introduces a sequence of intermediate values that each differ by exactly one bit. These intermediary values act as stepping stones that maintain signal integrity during rapid pointer transitions.
2Device complexity
If conventional binary-to-Gray conversion is used to simplify the encoding process, then the device complexity is reduced, but signal consistency is lost during burst mode operations
Solution Approach 1:
The patent applies segmentation by dividing the conversion process into multiple stages. Instead of performing a single direct binary-to-Gray conversion, the circuit segments the conversion into a sequence of smaller steps, each producing an intermediate Gray encoded value. This segmentation allows the circuit to maintain signal consistency by ensuring each individual transition maintains a Hamming distance of one, while still supporting burst mode operation through the sequence of intermediate values.
3Productivity
If the write pointer is incremented by more than one position in a single clock cycle, then the productivity is improved, but the Hamming distance between consecutive Gray values increases, leading to synchronization errors
Solution Approach 1:
The patent applies preliminary action by pre-generating the sequence of intermediate Gray encoded values that will be needed during the burst write operation. The conversion circuit calculates and prepares these intermediate values in advance, ensuring that when the burst write occurs, each pointer transition follows a path of Gray codes with unitary Hamming distance. This preliminary preparation enables high throughput while maintaining transition accuracy.
Solution Approach 2:
The patent applies dynamics by making the conversion process adaptive to the burst write requirements. The circuit dynamically generates intermediate Gray encoded values based on the specific burst parameters, adjusting the sequence of intermediate values to match the required pointer transitions. This dynamic approach allows the circuit to maintain precision regardless of the burst size or direction.
Data Source
AI summary
A circuit and method for performing a Binary-to-Gray conversion are disclosed. A first binary signal represents a target value and a second binary signal is stored in a register. A set of binary candidate values are determined where the respective Gray equivalent of each binary candidate value has a Hamming distance of one from the Gray equivalent of the second binary value. One of the binary candidate values is selected as a function of the first binary signal and the second binary signal. The selected binary candidate value is provided at input to the register. An encoded signal is generated by determining the Gray encoded equivalent of the selected binary candidate value.