Chapter 6: Concepts

Understanding Logic Analyzer Triggering

be used in place of Global Counters, if possible, because they are easier to use and because there is a limited number of Global Counters.

Next: “Timers” on page 248

Timers

Timers are used to check the amount of time that has elapsed between events. For example, if you want to trigger on one edge followed by another edge that occurs within 500ns, use a timer. The most critical point to remember in using timers is that they need to be started before they are tested. In other words, timers do not start automatically.

The key to setting up a timer is to identify where it should be started and where it should be tested. Consider the example in the following figure. The timer should be started when the rising edge on SIG1 is detected and it should be tested when the rising edge occurs on SIG2.

An edge followed by an edge with a time limit

An example trigger sequence to set up this measurement is:

1.If there is a Rising Edge on SIG1, then Start Timer1

Go to 2

2.If there is a Rising Edge on SIG2 AND Timer1 < 500ns then Trigger

While the above trigger sequence seems correct, it actually has a critical flaw. What happens if there is a rising edge on SIG1 but SIG2 doesn't occur within 500ns? The logic analyzer will never trigger,

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Agilent Technologies 16760A manual Next Timers on, An example trigger sequence to set up this measurement is, 248