Mesochronous Clock-Domain FIFO for Collision-Free Data Transfer
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Solution Overview
Problem
Error-free data transfer across clock domain boundaries is challenging when dealing with mesochronous clock domains, where the phase relationship between synchronizing clocks is arbitrary, leading to potential bit errors.
Innovation Solution
Implementing a FIFO register structure with coordinated write and read operations, where write operations are synchronized with the source clock domain and read operations with the destination clock domain, using state machines and pointers to ensure that data is not read from a register while it is being written, thereby preventing collisions and ensuring error-free data transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If data is transferred directly between mesochronous clock domains with arbitrary phase relationships, then device complexity is reduced, but data transfer reliability deteriorates due to potential bit errors from timing violations
Solution Approach 1:
A FIFO buffer is introduced as an intermediary data storage element between the sending and receiving clock domains. The FIFO buffer is controlled by state machines that coordinate read and write operations to ensure data is transferred reliably across clock domain boundaries with arbitrary phase relationships, preventing read/write collisions while maintaining data integrity
Solution Approach 2:
The data transfer mechanism is segmented into separate write and read operations controlled by independent state machines. The write operation is controlled by a write state machine synchronized with the source clock domain, while the read operation is controlled by a read state machine synchronized with the destination clock domain, allowing independent optimization of each operation
2Reliability
If a FIFO register structure with coordinated state machines is used, then data transfer reliability is improved, but device complexity increases due to additional control logic
Solution Approach 1:
The write state machine and read state machine are merged into a single coordinated control system that manages the FIFO buffer. Both state machines execute the same state sequence but are synchronized to different clock domains, allowing them to coordinate their operations and prevent collisions while reducing overall control logic complexity
Solution Approach 2:
The state machines serve multiple functions: they control both write and read operations, manage FIFO buffer pointers, detect full/empty conditions, and coordinate timing across clock domains. This multi-functionality reduces the need for separate dedicated control circuits for each operation
Data Source
AI summary
Error-free data transfer between mesochronous clock domains can be accomplished by writing data to and reading data from a plurality of data storage elements in coordinated fashion. Write operations are controlled by execution of a state sequence synchronously with the source clock domain, and read operations are controlled by execution of the same state sequence synchronously with the destination clock domain. The states respectively correspond to the data storage elements, and the read and write executions of the state sequence do not simultaneously assume the same state.