Digital Combinatorial Triggering

Triggering begins the Analyzer's data input and display processes. The trigger point is the reference point to which all following events are related.

The Analyzer's controls provide for triggering on either single events or multiple events occurring simultaneously. This capability is necessary in digital applications because digital systems commonly function in response to parallel data patterns occurring simultaneously on several circuit nodes. A device, for example, might be designed to accept data only when two control lines are HIGH concurrently. Therefore, synchronizing a measurement with the start of a process often requires the ability to recognize multiple simultaneous events. This the

Analyzer can do. It triggers on an AND combination of up to three signals or their complements.

A major Logic Analyzer design consideration was that all controls be simple to use and intuitively understood by digital users. The trigger section is a good example. All trigger switches are grouped in a shaded area on the front panel (Fig. 3). The algorithm describing trigger requirements is drawn on the front panel as a simple schematic diagram using common digital symbols.

Triggering requires a high-going edge at the output of the front-panel AND gate. Trigger data can originate at three inputs, A, B, and EXT TRIG, reaching the AND gate via the slope-control toggle switches in each of the three paths. When any of these three-position switches is set to the upper position, data is transmitted directly from the associated data input to the AND gate. With the switch in the middle position opposite the inverter, data is inverted before application to the gate. In the lower or OFF position, the input is removed from the trigger process.

trigger control

ARMED TRIGGERED

ISMOFF-1

off-

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