Framing Protocol for Low-Latency Serial Interface Emulation
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Solution Overview
Problem
Conventional processor-based emulation systems lack the ability to distinguish between mission and non-mission data, leading to unnecessary processing and power consumption during gap cycles, as they continue to route non-mission data and fail to efficiently manage data communication between ASICs.
Innovation Solution
A framing protocol is introduced that uses specific data packets, including start-of-packet and end-of-packet molecules, to indicate emulation cycles and gap cycles, allowing switching ASICs to route mission data during emulation cycles and cease routing during gap cycles, thereby optimizing data handling and resource utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional I/O interfaces and switching logic continue to route data during gap cycles, then data communication between ASICs is maintained, but processing resources are wasted and power consumption increases
Solution Approach 1:
The system performs preliminary actions by transmitting end-of-packet molecules during gap cycles before emulation cycles begin. This allows the switching logic to pre-configured and stop routing data in advance, ensuring that when emulation cycles start, the routing is already optimized and ready, eliminating the need to continuously route data during idle gap periods
Solution Approach 2:
The framing protocol implements periodic action by using distinct packet molecules (start-of-packet and end-of-packet) that are transmitted periodically to mark the beginning and end of data transmission phases. This periodic signaling allows the system to alternately route and stop routing data based on whether an emulation or gap cycle is active, reducing power consumption during gap cycles while maintaining routing continuity when needed
2Loss of information
If conventional I/O interfaces route all data during emulation cycles, then data communication is maintained, but mission data and non-mission data cannot be distinguished
Solution Approach 1:
The data stream is segmented into distinct packets with clear delimiters. Start-of-packet and end-of-packet molecules create discrete boundaries that allow the receiving I/O interface to identify and process only relevant mission data during emulation cycles, filtering out non-mission data without requiring complex analysis of the data content itself
Solution Approach 2:
The framing protocol acts as an intermediary layer between the data source and the I/O interface. By inserting start-of-packet and end-of-packet molecules as mediator signals, the system enables the receiving interface to distinguish mission from non-mission data without adding complex processing logic to the underlying I/O hardware, thus managing complexity at the protocol level rather than the hardware level
3Loss of energy
If data routing is stopped during gap cycles, then power consumption is reduced, but data transmission latency may increase when emulation cycles resume
Solution Approach 1:
The system performs preliminary actions by transmitting the start-of-packet molecule during the gap cycle immediately preceding the emulation cycle. This allows the receiving I/O interface to prepare and resume data routing just before the emulation cycle begins, minimizing the latency when data transmission needs to restart while still allowing routing to be stopped during earlier gap cycles for power savings
Data Source
AI summary
Using a framing protocol, an application specific integrated circuit (ASIC) in an emulation system may transmit a start-of-packet molecule to a serializer-deserializer (SerDes) interface of a switching ASIC in a gap cycle leading up to an emulation cycle such that the switching ASIC may start routing mission data through the SerDes interface during the emulation cycle. The ASIC may transmit an end-of-packet molecule at a first gap cycle to the SerDes interface of the switching ASIC such that the switching ASIC may stop routing data through the SerDes interface during the gap cycles. The start-of-packet molecule may include a start-of-packet word, a status word, cyclic redundancy check word, and an idle word. The end-of-packet molecule may include an end-of-packet word, a status word, a cyclic redundancy check word, and an idle word.