Understanding Eye Scan Measurements | Agilent Technologies 16760A

Chapter 6: Concepts

Understanding Eye Scan Measurements

Eye scan measurements are made possible by the logic analyzer's ability to double-sample each channel using slightly offset delays and by comparing the delayed samples using an exclusive-OR operation.

When the exclusive-OR output is high, the delayed samples are different, and a transition is detected between the delay times.

Because of jitter and other variations in the sampled signal, an eye scan measurement checks many clocks for each pair of delay values so that it can report how often transitions occur between the two delay times.

Then, another pair of delay values is checked, and so on, until a whole range of time is scanned for transitions.

Because the logic analyzer is able to adjust the threshold voltage for channels, an eye scan measurement is able to repeat the scan for transitions over time at many threshold voltage levels.

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Agilent Technologies 16760A manual Understanding Eye Scan Measurements, 259

Contents

Agilent Technologies. All rights reserved Agilent Technologies 16760A Logic Analyzer Probing Captures input signals as low as 200 mV p-pSampling Mode on Agilent Technologies 16760A Logic Analyzer Concepts on Reference on Glossary see See Also Contents Choosing the Sampling Mode 114 Using Symbols 101110 112 Format Tab 174 Displaying Captured Eye Scan Data152 155 210 Eye Scan Tab 204211 240 Specifications and Characteristics259 Glossary Index Contents Getting Started Eye scan sampling mode, measurements will have these steps Next . Choose the sampling mode on Probing and Sampling Mode Selection StepsConnect logic analyzer to the device under test To choose the sampling mode Choose the sampling mode If you chose State Mode If you chose Timing Mode Either Timing Mode or State Mode Next . Format labels for the probed signals onIf you chose Eye Scan Mode Format labels for the probed signals To specify threshold voltages To assign pods to the logic analyzer Defined threshold voltage Select the Close button NextTo assign names to logic analyzer channels Define the trigger condition Timing Mode or State Mode Steps Next . Run the measurement on Run the measurement Next . Display the captured data on Display the captured dataTo open Waveform or Listing displays To add display tools via the Workspace window Next For More Information... on Select channels for the eye scan measurement Eye Scan Mode Steps Next . Set the eye scan range and resolution on Set the eye scan range and resolution Next . Run the eye scan measurement on Run the eye scan measurement Next . Display the captured eye scan data on Display the captured eye scan data Eye Scan display window, use the following subtabs For More Information For More Information Probing and Selecting the Sampling Mode Probing and Selecting the Sampling Mode Probing the Device Under Test Using the E5378A Single-Ended Probe Either Single-ended signalNumber Numbers Using the E5379A Differential Probe Reference voltage Or single-ended signalsIndependent threshold adjustment Negative data inputs Or AMP Using the E5380A Mictor-Compatible Probe Using the E5382A Single-ended Flying Lead Probe Set Additional Accessories Using an Analysis Probe Probing the Device Under Test Selecting the Timing Mode Asynchronous Sampling Choosing the Sampling Mode To select the conventional/transitional configuration To select the timing mode Sample rate is the inverse of the sample period To specify the sample period To manually adjust sampling positions on Selecting the State Mode Synchronous SamplingState Mode Sampling Position To automatically adjust sampling positions on To select the state speed configuration To select the state mode For the clock input signal that will be used To set up the sampling clock Automatically sets the sampling position To automatically adjust sampling positionsRun simultaneously To run eye finder repetitively Choose the labels that you wish to run eye finder on To view eye finder data as a stack of channels To view eye finder data as a bus compositeTo save/load eye finder data Eye Finder Advanced Settings Dialog on To manually adjust sampling positionsEye finder data must be saved and loaded separately To specify the trigger position Either Timing Mode or State ModeTo set acquisition memory depth You can also name analyzers in the Pod Assignment Dialog on To name an analyzerTo turn an analyzer off or on You can give more descriptive names to a logic analyzer High-speed or high-bandwidth oscilloscope Selecting the Eye Scan ModeTo select the eye scan mode To select the eye scan mode speed configuration To set up the eye scan mode reference clock Formatting Labels for Logic Analyzer Probes Format tab has activity indicators that show signal levelsTo assign pods to the analyzer To set up qualified eye scan measurements on Capturing Data on 17 Channels in State ModeTo set pod threshold voltages To set clock threshold voltages To assign probe channels to labels Label off Maximum of 32 channels can be assigned to a labelTo delete labels Label SignalsTo import label names and assignments from a netlist E5378A and E5380A probe types to be selectable To assign label name Blue to channel 5 on pod A2 To import label definitions from an Ascii fileLabel Definition File Format Examples To change the label polarity To export label definitions to an Ascii fileChannel 5 on pod A2, and channel 6 on pod A1 Changing the label polarity will have the following effects To reorder bits in a labelChanging the label polarity does not affect To display a label that was off To turn labels off or onTo turn a label off To turn a label on Using the Logic Analyzer in Timing or State Mode Using the Logic Analyzer in Timing or State Mode Use trigger functions for basic measurements Setting Up Triggers and Running MeasurementsGeneral To select a trigger function Using Trigger Functions To specify a label pattern event Timing only To specify a label edge event To enter symbolic label values on Symbols Selector Dialog on To compress a trigger function To expand a trigger function To copy trigger function libraries between systems To load/unload trigger function libraries To count time, states, or turn counting off Using Other Trigger Features If you chose Custom To specify default storingTo assign pods to the analyzer on Reduced by half in order to store the required time tags To clear default storing changes Acquisition option button and choose either On or Off Default storing is initially on or offTrigger tabs Default Storing subtab, select the At start To insert a store action state mode on To replace sequence levels To insert/replace/delete sequence levelsTo clear the trigger sequence on To insert sequence levels To cut/copy-and-paste sequence levels Setting Up Triggers and Running Measurements Example system14 Slot C Analyzer C has triggered Trigger tab, select the Overview subtab To restore default trigger settingsTo view a picture of the trigger sequence To clear the trigger sequence To specify a time duration for events timing only To specify a duration or occurrence count for events Available To insert a store action state modeTo insert timer actions/events To insert a timer action To insert a counter event To insert a timer eventTo insert counter actions/events To insert a counter action To insert flag actions/events To insert a flag event To drive the Port Out signal with a flag To group events To insert a reset occurrence counter actionTo use named events To insert a named event Saving/Recalling Trigger SetupsTo save a trigger setup To give an event list a name To start/stop measurements To recall a trigger setupRunning Measurements To clear the trigger save/recall list Waiting for Trigger on If nothing happens when you start a measurementTo stop a measurement Select the Stop or Stop All button To view the trigger status To open Waveform or Listing displays Displaying Captured Data Search for particular data values captured on labels Help volumeTo use other display tools Windows Displaying Captured Data Into parallel words which are easier to view and analyze Analyzer help volumeIntermittent Data Errors Unwanted Triggers If the captured data doesnt look correct This situation will occur in these cases If there are filtered data holes in display memory To view symbolic values in a waveform display To display symbols for data valuesTo view symbolic values in a listing display Select the Cancel button To cancel the display processing of captured data100 You can use symbol names in place of data values when Using Symbols101 To reload object file symbols To load object file symbols102 Object file symbols are reloaded To adjust symbol values for relocated code 104 To create user-defined symbolsWhose symbols you wish to relocate To replace user-defined symbols To load user-defined symbols To enter symbolic label valuesWhen entering label values in the trigger sequence To delete user-defined symbols General-Purpose Ascii GPA Symbol File Format on To create an Ascii symbol file106 Create the reader.ini file on your workstation or PC Examples Example for Elf/Stabs StabsTypeReadOnlyTicoffPage AppendTicoffPage Example for Ticoff Example for Coff/Stabs using Ticoff reader109 You can print captured data from display tool windows Printing/Exporting Captured Data 111 Select the file name and automatic file sequencing optionsSelect the Read File button Icon to view the imported data To cross-trigger with another instrument Cross-Triggering112 113 When the logic analyzer drives the arm signal 114 Solving Logic Analysis ProblemsTo test the logic analyzer hardware To test the logic analyzer hardware on System help volume Service Center for assistance115 116 Saving and Loading Logic Analyzer ConfigurationsTo save logic analyzer configurations To load logic analyzer configurations 117 Using the Logic Analyzer in Eye Scan Mode 118 119 Setting Up and Running Eye Scan MeasurementsEye Scan tab lets you set up and run Eye Scan measurements To select channels for the eye scan Scan Settings Subtab on To set the eye scan range and resolution120 121 To quickly set up another measurement using the scale seeTo run an eye scan measurement To set advanced eye scan options Advanced Subtab on To set up qualified eye scan measurements122 Memory device versus a memory controller Requirements Signal Timing Burst Transfers123 Before the clock edge to after it Has adjustable sampling positions on each input channelBurst After the rising edge of the clock Are supported Clock cycle of the next burst125 126 127 Be sure that the thresholds are set correctly Display For correct state mode acquisitionsNot already expanded Start your target system and select Run Eye Finder 129 Now, set up eye scan mode 130 Select the Eye Scan tab Select the Qualifier subtab 131 Select the Qualify eye scan sampling using... button To comment on the eye scan settings To open the Eye Scan display Displaying Captured Eye Scan Data133 134 To select the channels displayedTool Within the data captured on the bus Eye Scan display window, select the Scale tab To scale the Eye Scan displayScale tab, you can To use the scaling options To open the Eye Scan display on To quickly set up another measurement using the scaleTo set Eye Scan display options To clear the captured eye scan data 137 138 139 140 To change the Eye Scan color scale Make measurements on the eye scan data on Is zero by default141 About the captured measurement data To make measurements on the eye scan data142 143 144 145 146 147 148 149 To display information about the eye scan dataScroll bars to navigate through the information Eye Scan display window, select the Info tab 150 Info tab, you can 151 To comment on the eye scan data Saving and Loading Captured Eye Scan Data Loading Logic Analyzer Configurations on152 153 Sampling Tab on Format Tab on Trigger Tab on 154 Sampling tab lets you choose between the logic analyzers Sampling Tab155 156 Timing ModeConventional Transitional Acquisition Samples with transitions How Samples are Stored in Transitional TimingWill be stored Period and other times more than two sample periods apart State Speed State Mode158 159 Sampling Positions Dialog File menu Lets you save/load eye finder data Sampling Positions Tab160 161 Label buttonsDisplay Area Sampling Position Cannot run the Eye Finder at this time How the Selected Position BehavesHow the Suggested Position Behaves XX% complete 163 Cannot run the Logic Analyzer at this timeCharacterizer cannot be loaded Complete Date Select one or more labels in the Eye Finder Setup tab 165 Timeout N K clocks in 5 secThis channel appears to be completely quiet Two common possibilities exist 166 Run Eye Finder to characterize this channelSee individual channels for messages Stable region extends beyond the limits of the display Disk is probably full Numerical value for the item XXX could not be read Unsupported revision level AA.BB Failed to open file for reading/writing NameFile Name already exists. Overwrite? Invalid true/false flag 169 Eye Finder Setup Tab 170 Eye Finder Advanced Settings Dialog 171 File Info Tab Save As Eye Scan ModeReload Save 173 Selecting the Eye Scan Mode on Specify the logic analyzer pod and clock threshold voltages Expander cards which cannot be used in the clock setupFormat Tab Data Pods Pod Assignment DialogName Type 176 Trigger Tab 177 Trigger Functions Subtab 178 General Timing Trigger Functions 179 180 General State Trigger Functions 181 Find pattern1 eventually followed by pattern2 182 183 Advanced Trigger Functions 184 Searched for Turbo State Trigger FunctionsState Trigger Functions Advanced pattern1 or pattern2 186 187 Half Channel State Trigger Functions 188 Settings SubtabCount Intermodule Control This tab gives a picture of the trigger sequence Overview Subtab189 Group events Default Storing SubtabEvent Specification List At start Acquisition Save/Recall Subtab Status Subtab191 192 Creating trigger function libraries Multiple files Symbols TabTwo kinds of symbols are available That you use to set up resource terms 194 Object file versions See Also Matching Symbols Symbols Selector Dialog195 Offset By Option Search PatternAddress masking is done by the Align to x Byte option Qualifies any address from 100C through 100F Symbol File FormatsAlign to x Byte Option Byte option allows you to mask off an address 107 file General-Purpose Ascii GPA Symbol File Format198 Format GPA Record Format Summary199 Definitions in the file Records200 Last address of the section, in hexadecimal Symbol representing the name of the sectionSymbol representing the function name First address of the section, in hexadecimal 202 You can specify symbols for variables usingName of a file Number of a line in the file, in decimal 203 Comments Collapse Shows labels only Select All Selects all channels Eye Scan TabLabels Subtab Expand Time Scan Settings SubtabRun Mode Scan Range 206 Advanced Subtab Custom ShortMedium Long Names for Qualifier SubtabQualification Clock Edge to Sample 209 Comments Subtab Calibration Messages Calibration TabCalibration Instructions Calibration Status 211 Error Messages General Guidelines Branch expression is too complex212 213 Specific Guidelines 200 Mb/s State and all Timing Modes 214 If the following sequence does not compileThis one may Specific Guidelines 400 Mb/s State Modes 215 Specific Guidelines 1250/1500 Mb/s State Mode Specific Guidelines 800 Mb/s State Mode216 217 Last sequence level calls goto next Goto action specifies an undefined levelHardware Initialization Failed Possible Causes Timing sampling mode, flags are are always available Maximum of 32 Channels Per LabelMust assign another pod pair to specify actions for flags No more Edge/Glitch resources available for this pod pair 220 Possible SolutionsNo more Pattern resources available for this pod pair Phrase some of the edges as patterns Slow or Missing Clock No Trigger action found in the trace specification221 222 Trigger function initialization failure 223 Trigger inhibited during timing prestoreTrigger Specification is too complex Then the approximate time is 32 seconds Event Combiner resource allocation guidelines224 Misaligned boundaries for addresses Waiting for Trigger225 226 To save a trigger setup on 227 Specifications and CharacteristicsOperating temperature 0 to 45 degrees C Probes E5378A Input Equivalent Circuit E5378A Single-Ended Probe Specifications CharacteristicsE5379A Differential Probe Specifications Characteristics All specifications are marked by * asterisk 229 E5379A Input Equivalent Circuit E5380A Input Equivalent Circuit 1500 Mb/s Sampling Mode Specifications and Characteristics230 231 Characteristics 232 233 400 Mb/s Sampling Mode Specifications Characteristics 234 200 Mb/s Sampling Mode Specifications Characteristics 235 Conventional Timing Mode Specifications and CharacteristicsTransitional Timing Mode Specifications and Characteristics All specifications are marked by * asterisk 236 What is a Specification? 237 What is a Characteristic?What is a Function Test? Referred to as an operational accuracy calibration 238 239 Concepts Conveyor Belt Analogy Understanding Logic Analyzer Triggering240 241 Conveyor belt analogy Next Sequence Levels on Summary of Triggering CapabilitiesSequence Levels Next Summary of Triggering Capabilities on 243 Addr Data 244 Boolean Expressions Next Ranges on BranchesEdges Ranges Trigger Sequence for Module FlagsOccurrence Counters and Global Counters Next Flags on An edge followed by an edge with a time limit TimersNext Timers on An example trigger sequence to set up this measurement is Needed Default StorageStorage Qualification Next Storage Qualification on 250 Sequence Level Storage 251 Strategies for Setting Up TriggersNext Strategies for Setting Up Triggers on Trigger Functions Pattern2 occurring immediately after Pattern1 Agilent 16715A trigger user interface252 Store range until pattern occurs Same trigger as If/Then statements253 Next Document Your Trigger Sequences on Setting Up Complex TriggersNext Setting Up Complex Triggers on Document Your Trigger Sequences Inline documentation on an Agilent logic analyzer ConclusionsDifferent parts of the trigger to describe how they work Next Conclusions on To accurately capture data on a bus Understanding State Mode Sampling Positions256 257 258 Window 259 Understanding Eye Scan Measurements 260 261 Measurements run simultaneously in parallel Voltage resolution that can be set is 1 mVUsing the Logic Analyzer in Eye Scan Mode on Are multiple logic analyzer cards in a module in this case Asterisk * See edge terms, glitch, and labels Glossary263 264 Divided into 1K 64-state records 265 Debug mode See monitor 266 Ethernet address See link-level 267 268 269 Module/probe interconnect cable Processor probe See emulation By the channel width of the instrument270 271 Measurements 272 273 274 275 Index 251 276 247 277 122 278 180 279 280 Label values, symbolic, 105 labels, 22 Positive logic 281 242 282 107 283 Wait for other machine to trigger 284 Publication Number 5988-9044EN January 1