Memory Hub Built-In Self-Test Logic for High-Speed Bus Bring-Up
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Solution Overview
Problem
High-speed, high-reliability computer memory systems face challenges in initial bring-up, characterization, and validation due to complex operations, tight timing margins, and small signal swings, which complicate traditional test and diagnostic methods, leading to increased time and effort in identifying root-cause failures.
Innovation Solution
A memory hub device with integrated test logic, including a built-in self-test apparatus, configuration registers, command collision detection logic, and a configured command sequencer, enables simultaneous and independent testing of memory devices, reporting fault and diagnostic information, and supporting flexible communication protocols to manage high-speed bus operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional test equipment and probing methods are used to characterize memory systems during bring-up and operation, then traditional diagnostic capabilities are maintained, but high-speed busses and memory device interfaces cannot properly transfer information, preventing effective testing
Solution Approach 1:
The patent introduces an intermediary testing mechanism that operates through the high-speed bus interface itself, using test data packets that traverse the same communication path as operational data. This intermediary approach allows fault detection without requiring external probing equipment that would disrupt the high-speed communication.
Solution Approach 2:
The memory system performs self-diagnosis by incorporating test logic within the hub device that can autonomously generate, transmit, and analyze test patterns through the high-speed bus. This self-service capability eliminates the need for external test equipment and allows the system to detect faults using its own operational infrastructure.
2Ease of operation
If traditional hardware and software diagnostic methods are used during initial bring-up and memory operations, then basic diagnostics are available, but the complexity and large number of operations performed dramatically increase time and effort required to complete bring-up and identification of root-cause failures
Solution Approach 1:
The patent implements preliminary diagnostic actions by integrating test logic that automatically executes during the initial bring-up sequence. Test patterns are generated and transmitted before full operational mode is established, allowing early detection of interface faults and reducing the time required for subsequent debugging and root-cause analysis.
Solution Approach 2:
The system incorporates feedback mechanisms where test results are immediately captured and analyzed by the hub device. Configuration registers provide real-time status information about test outcomes, enabling rapid identification of faults and reducing the iterative debugging time associated with traditional diagnostic methods.
3Productivity
If high DRAM operating frequencies are coupled to intermediary devices via high-speed busses to increase performance, then system performance and density are improved, but conventional test equipment cannot properly transfer information, complicating test and diagnostic procedures
Solution Approach 1:
The hub device incorporates multi-functional logic that serves both operational data transmission and diagnostic testing through the same high-speed bus interface. The test logic can operate in conjunction with normal memory operations, allowing the system to maintain high performance while integrating diagnostic capabilities without requiring separate specialized test equipment.
Data Source
AI summary
A memory hub device with test logic is configured to communicate with memory devices via multiple hub device ports, and is also configured to communicate on one or more busses in an upstream and downstream direction. The test logic includes a built-in self test apparatus providing logic to simultaneously and independently test the memory devices interfaced to one or more of the hub device ports using read and write data patterns. The test logic also includes configuration registers to hold fault and diagnostic information, and to initiate one or more tests. The memory hub device can further include command collision detection logic, a trace array, buffer transmit mode logic, trigger logic, clock adjustment logic, transparent mode logic, and a configured command sequencer, as well as additional features.