Logic analyzer

A logic analyzer (English Logic Analyzer ) is an electronic measuring instrument that can record the timing of digital signals and visualize. It is used for testing and debugging of digital electronic circuits, for example in the development of computers and electronic control units. Against oscilloscopes provide substantially more logic analyzers inputs (typically 16 to several 100) show, however, in the Y- axis, as a rule only discrete logic values. These generally include the Boolean truth values of the binary digital technology false ( "0") and true ( " 1"). Depending on the equipment other values can be detected and displayed. Examples are undefined voltage level or the high-impedance state of a line ("Z" / "high impedance ").

As a hybrid of logic analyzers and oscilloscopes, there are hybrid devices that record continuous analog signals together as so-called mixed-signal devices with discrete digital signals and can display on the same time axis.

A logic analyzer can trigger on a complex sequence of digital events ( trigger ) and then record a large amount of digital data from the monitored system. In addition, some models offer advanced analysis and presentation methods; Thus, for example, the sequence of a computer program such as illustrated with a software debugger, ie in disassembled form when the inputs are connected to address and data bus of a microprocessor. In addition, the activities can possibly be analyzed and presented to the said buses in its details and different phases. This is all very dependent on the particular processor model, so that it is essential for a logic analyzer such that it can be adapted to a particular processor, for example by plug-in module or adapter.

When the first logic analyzers were introduced, it was common to connect up to several hundred terminals to a digital system. And specialized multi-pole connectors were later used for this, which have already been provided with the development of the circuit.

In modern computer systems, various other tools have replaced the logic analyzers for many purposes. Many microprocessors have now built-in hardware support for software debugger and diagnostic interface (see boundary scan), over which the input / output terminals and internal register structures are assigned values (simulated input ) and can be queried.

Most digital circuits, and also particularly the internal circuits of integrated circuits are simulated in the development, in order to detect defects before the circuit or the chip is manufactured. In the simulation programs to usually are ads available that offer similar features as standalone logic analyzers.

None of these methods, the high -speed data recording of a logic analyzer reproduce exactly, but they cover most of the actual requirements from in order to test digital circuits, and are usually cheaper to use.

Hardware emulator

While the logic analyzer pursued purely passive events in a computer hardware that includes a hardware emulator beyond even the processor part itself and is inserted with this in the computer hardware (usually plugged in ) in order to analyze in more detail, see in the emulator.

Logic analyzer

Hardware emulator

See also