Timing Measurements; Introduction; Glitches; Triggering - HP 1630A Operating And Programming Manual

Model 1630A/D/G
Timing Measurements
INTRODUCTION
Chapter 6
Timing Measurements
Timing analysis is directed toward timing relationships between I/O signals or control lines, and propagation
delays between or across logic gates.
When the logic analyzer is configured fortiming analysis, samples of data are taken, asynchronously, on every
pulse of a clock internal to the analyzer. The analyzer determines whether the data is less or greater than a
prespecified threshold voltage level and displays the result as either a logic 1 or 0 . The display stays at the same
level until the next sample is taken .
Glitches
Glitches are handled bya glitch detection circuitwhich is independentof the sampling rate . Dual detectors are
on an alternate sample period with a slight overlap . Each detector looks for two threshold crossings,
identifying a glitch . If a glitch is found, it is stored in a memory separate from the timing data . When glitch
detection is on, the assigned timing channels are halved .
Triggering
Trigger detection is accomplished by a method independent of the sampling clock. To eliminate false
triggering, the analyzer has a filter which is used when specifying trigger duration . Trigger pattern duration is
selectable from 20ns to 1ms to qualify the trigger on a time basis.
Edge triggering is available on four channels per pod assigned to timing measurements . It is used where a
pattern may not be adequate for triggering or may be used to qualify a pattern . With edge detection, triggering
can take place on an edge that doesn't show up in the trace (glitch triggering) .
When the analyzer finds the trigger, thetracepoint is positioned asspecified in the specification menu (at start,
center, or end of trace) . The trace specification tells the analyzer when to stop the measurement. Enough
information is captured after the triggerto place it properly in trace memory . Usually timing measurements are
taken with the trigger in the center trace position . The tracepoint may be delayed up to 9999 seconds afterthe
trigger.
SIMPLE TIMING MEASUREMENTS
The following procedure shows how to make measurements of time-related activity in logic systems. How to
trigger traces of electrical activity and how to compose desired displays and measure activity on the displays
are described in step by step processes.
Activating The Timing Analyzer
1 . Press the SYSTEM key.
2. Press the ROLL down key one time or CURSOR down key two times. This moves the bright bar to the
second analyzer configuration . All channels which can collect timing information are activated for
timing measurements .