High Speed Memory Debug Techniques

1. High Speed Memory Debug Techniques presented by:Jennie GrosslightProject Development ManagerMemory Solutions FuturePlus® Systems Corporation

2. Basic Strategy: Eliminate unlikely causes thru quick checks and automated tools so you can… Go deep on most likely causes with thorough checks High Speed Memory Debug Techniques

3. Marginal timing relationships Protocol violation Clock integrity issues SI failures Other possibilities Incorrect BIOS setting for On Die Termination (ODT) Invalid Cas latency Errors from other buses Typical Causes of Memory Failures

4. High Speed Memory Debug Techniques • Determine if the failure is repeatable. • Connect a logic analyzer to the memory bus with a probe or interposer to gain rapid insight   • Run SW tests on LA traces   • Parametric measurements Applicable to any SDRAM, Embedded or Standard Slots

5. Root cause of the problem can come from a sub-system or applications that are not directly connected to memory. LAN access, power sequences of subsystems, entering and exiting sleep modes, and power cycles. Cross talk and conflicting resources from a variety of sub-systems, modes, and cycles. Isolation of a problem during a specific test or set of conditions   Review error logs and identifying what software was running at the time of the failure. Environmental variants - What was the room temperature when the system failed? Check the airflow to system. Determine if failure is repeatable

6. Hardware - Is the power to the system within specifications? Has a system of this same design ever passed validation tests? Do other systems fail or is this failure unit specific? What are the revisions on the board, DIMM, processor, or other components of the failed system? How does the failed system differ from working systems? Have there been recent component changes in manufacturing? If conditions are repeatable, run your tests under those conditions, if not chose a robust memory test and vary the test conditions, such as temperature and power supply limits, in a methodical manner. Determine if failure is repeatable

7. High Speed Memory Debug Techniques • Determine if the failure is repeatable. • Connect a logic analyzer to the memory bus with a probe or interposer to gain rapid insight • Timing Zoom • Eye finder and Eye Scan • State listing/waveforms • Markers • Filters • Run SW tests on LA traces   • Parametric measurements Applicable to any SDRAM, Embedded or Standard Slots

8. Timing Relationships • Key Points: • LA provides rapid insight of timing relationships of entire bus. • 64k of high resolution timing adjustable about trigger • Markers for quick measurements • Clock frequency • Data valid windows • CAS latency 64k deep 250ps resolution trace

9. Eye Finder – Insight-at-a-glance Clock Signal Integrity Time=0=clock edge • In this example, lower screen reveals Clock noise. Apparent by wider transition area at Time=0=clock edge. • Additional information • Setup /hold of address and control lines • Relative skew of address/control signals Clean clock Dirty clock

10. Eye Scan – In depth insight • 10ps / 5mV resolution eye diagrams • Rapid Detection • signals with parts per million errors • Skew • Recognition of Parts per Million error allows in depth investigation of signals with errors as opposed to investigating all signals

11. State trace list with protocol decode allows detailed protocol check Global markers placed in State or Waveform window track to all LA windows View Specific Violations

12. Markers and Measurements

13. Examples of Failures Protocol Error Patterns left to right: • B0 Activate (pink) • B0 Writes (red) • B1 Activate Missing (turquoise) • B1 Read (light blue) • Using Colorized filter for pattern recognition. Patterns possible include: • RAS / CAS delay • CAS latency • Precharge interval • Overview of memory access • Page access pattern

14. High Speed Memory Debug Techniques • Determine if the failure is repeatable.   • Connect a logic analyzer to the memory bus with a probe or interposer to gain rapid insight • Run SW tests on LA traces   • Parametric measurements Applicable to any SDRAM, Embedded or Standard Slots

15. SW macro finds smallest data eyes

16. SW macro finds functional errors

17. High Speed Memory Debug Techniques • Determine if the failure is repeatable.   • Connect a logic analyzer to the memory bus with a probe or interposer to gain rapid insight   • Run SW tests on LA traces   • Parametric measurements Applicable to any SDRAM, Embedded or Standard Slots

18. Comprehensive Data Analysis Complete Jitter Analysis RJ/DJ (ISI,DCD, Periodic jitter) separation Jitter histograms Spectral analysis Traceable to individual bits Bathtub BER analysis Masks Real Time Eye Eye unfolding identifies failure pattern FBD Fixture control and compliance test suite integration

19. Summary: Eliminate unlikely causes thru quick checks and automated tools so you can… Go deep on most likely causes with thorough checks High Speed Memory Debug Techniques FuturePlus® Systems Corporation