USB Synchronization Using Variable SLOS1 Lengths to Break LOCK1 Loops
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Solution Overview
Problem
The USB4 training state can fail due to an infinite loop caused by erroneous order sets during synchronization, preventing successful completion and data transmission.
Innovation Solution
Implement a method where the transmitter sends first and second SLOS1 ordered sets with varying lengths during the LOCK1 state to break the infinite loop and facilitate synchronization with the receiver.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the transmitter and receiver follow the standard Training state machine with identical SLOS1 ordered sets, then synchronization can be achieved under normal conditions, but an infinite loop occurs when erroneous order sets are transmitted, causing training state failure
Solution Approach 1:
The patent changes the length parameter of SLOS1 ordered sets transmitted during the LOCK1 state. Specifically, it transmits a first SLOS1 ordered set with a first length, then a second SLOS1 ordered set with a second length different from the first. This parameter variation allows the receiver to detect and break out of infinite loops caused by erroneous order sets, thereby improving training state completion reliability without significantly increasing protocol complexity.
2Ease of operation
If the transmitter continuously sends identical SLOS1 ordered sets in LOCK1 state, then the protocol remains simple and easy to implement, but the system cannot detect or recover from transmission errors, leading to training state failure
Solution Approach 1:
The patent implements periodic variation in the SLOS1 ordered set transmission during the LOCK1 state. Instead of sending identical ordered sets continuously, the transmitter periodically changes the length of SLOS1 ordered sets (first length, then second different length). This periodic variation provides a simple yet effective mechanism for error detection and recovery, maintaining ease of implementation while significantly improving reliability.
3Measurement precision
If the receiver uses standard synchronization logic comparing received SLOS1 with stored information, then normal synchronization works correctly, but erroneous order sets cause the state machine to revert to LOCK1 state creating an infinite loop
Solution Approach 1:
The patent applies preliminary action by varying the length of SLOS1 ordered sets before the receiver performs comparison. The transmitter sends SLOS1 ordered sets with different lengths (first length, then second different length) during the LOCK1 state. This preliminary variation allows the receiver to detect errors before they cause infinite loops, maintaining measurement precision while improving synchronization state stability.
Data Source
AI summary
A method of synchronization in a training state of USB includes sending first SLOS1 ordered sets by a transmitter in a LOCK1 state and receiving the first SLOS1 ordered sets by a receiver in the LOCK1 state. The method further includes sending second SLOS1 ordered sets by the transmitter and receiving the second SLOS1 ordered sets by the receiver. A length of the second SLOS1 ordered sets is different from a length of the first SLOS1 ordered sets. The transmitter and the receiver then enter a LOCK2 state. The USB system includes a transmitter and a receiver coupled to the transmitter. The transmitter sends training ordered sets comprising the first SLOS1 ordered sets and the second SLOS1 ordered sets during the LOCK1 state, where the second SLOS1 ordered sets have a different length than the first SLOS1 ordered sets.