logic analyzer

A logic analyzer is an electronic instrument that captures and displays multiple logic signals from a digital system or digital circuit. A logic analyzer may convert the capture into timing diagrams, protocol decodes, state machine traces, opcodes, or may correlate opcodes with source-level software. Logic analyzers have advanced triggering capabilities, and are useful when a user needs to see the timing relationships between many signals in a digital system.

Overview

Presently, there are three distinct categories of logic analyzers available on the market: Modular LAs, which consist of both a chassis or mainframe and logic analyzer modules. The mainframe/chassis contains the display, controls, control computer, and multiple slots into which the actual data-capturing hardware is installed. The modules each have a specific number of channels, and multiple modules may be combined to obtain a very high channel count. While modular logic analyzers are typically more expensive, the ability to combine multiple modules to obtain a high channel count and the generally higher performance of modular logic analyzers often justifies the price. For the very high end modular logic analyzers, the user often must provide their own host PC or purchase an embedded controller compatible with the system. Portable LAs, sometimes referred to as standalone LAs. Portable logic analyzers integrate everything into a single package, with options installed at the factory. While portable logic analyzers generally have lower performance than their modular counterparts, they are often used for general purpose debugging by cost conscious users. PC-based LAs. The hardware connects to a computer through a USB or Ethernet connection and relays the captured signals to the software on the computer. These devices are typically much smaller and less expensive because they make use of a PC's existing keyboard, display and CPU.

History

As digital computing and integrated circuits emerged in the 1960s, new and difficult problems began to arise, problems that oscilloscopes had trouble handling. For the first time in computing history, it became essential to simultaneously view large numbers of signals. Early solutions attempted to combine hardware from multiple oscilloscopes into one package, but screen clutter, a lack of definite data interpretation, as well as probing constraints made this solution only marginally usable. The HP 5000A Logic Analyzer, introduced in the October 1973 issue of the Hewlett-Packard Journal, was probably the first commercially available instrument to be called a "Logic Analyzer". However, the HP 5000A was limited to two channels and presented information by means of two rows of 32 LEDs. The first truly parallel instrument was the twelve channel HP 1601L, it was a plug-in for the HP 180 series oscilloscope mainframes and used the oscilloscope screen to present 16 rows of 12 bit words as 1s and 0s. It was introduced in the January 1974 Hewlett-Packard Journal.

Mixed-signal oscilloscopes

Mixed-signal oscilloscopes combine the functionality of a digital storage oscilloscope with a logic analyzer. The several benefits of these include the ability to view analog and digital signals together in time, and to trigger on either digital or analog signals and capture on the other. A few limitations of mixed signal oscilloscopes are that they do not capture state-mode data, they have a limited channel count, and do not provide the analytical depth and insight of a logic analyzer.

References

External links

Feeling Comfortable with Logic Analyzers - Keysight

Text derived from https://en.wikipedia.org/w/index.php?oldid=1372214615 under CC BY-SA 4.0; modifications have been made.

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