| Logic Analyzer |
Logic Analyzer | A logic analyzer displays signals in a digital circuit that are too fast to be observed by a human being and presents it to a user so that the user can more easily check correct operation of the digital system. Logic analyzers are typically used for capturing data in systems that have too many channels to be examined with an oscilloscope. Software running on the logic analyzer can convert the captured data into timing diagrams, protocol decodes, state machine traces, assembly language, or correlate assembly with source-level software. Image File history File links Metadata Size of this preview: 750 × 600 pixelsFull resolution (1280 × 1024 pixel, file size: 173 KB, MIME type: image/jpeg) Daichinger took this picture of a 16902A Agilent Logic Analyzer I, the copyright holder of this work, hereby release it into the public domain. ...
Digital circuits are electric circuits based on a number of discrete voltage levels. ...
Illustration showing the interior of a cathode-ray tube for use in an oscilloscope. ...
In the theory of computation, a finite state machine (FSM) or finite state automaton (FSA) is an abstract machine that has only a finite, constant amount of memory. ...
See the terminology section, below, regarding inconsistent use of the terms assembly and assembler. ...
Current analyzers are either mainframes, which consist of a chassis containing the display, controls, control computer, and multiple slots into which the actual data capturing hardware is installed, or standalone units which integrate everything into a single package, with options installed at the factory.
Agilent and Tektronix make up over 95% of the industry's revenue. ...
Tektronix is a United States corporation that is currently a major presence in the test, measurement, and measuring industry. ...
Operation
A logic analyzer can trigger on a complicated sequence of digital events, and then capture a large amount of digital data from the system under test (SUT). The best logic analyzers behave like software debuggers by showing the flow of the computer program and decoding protocols to show messages and violations. A debugger is a computer program that is used to test and debug other programs. ...
A computer program is a collection of instructions that describe a task, or set of tasks, to be carried out by a computer. ...
When logic analyzers first came into use, it was common to attach several hundred "clips" to a digital system. Later, specialized connectors came into use. The evolution of logic analyzer probe has led to a common footprint that multiple vendors support, which provides added freedom to end users. Introduced in April, 2002, connectorless technology (identified by several vendor specific trade names: Compression Probing; Soft Touch; D-Max) has become popular. These probes provide a durable, reliable mechanical and electrical connection between the probe and the circuit board with less than 0.5pF to 0.7 pF loading per signal.
Once the probes are connected, the user programs the analyzer with the names of each signal, and can group several signals into groups for easier manipulation. Next, a capture mode is chosen, either timing mode, where the input signals are sampled at regular intervals based on an internal or external clock source, or state mode, where one or more of the signals are defined as "clocks," and data is taken on the rising or falling edges of these clocks, optionally using other signals to qualify these clocks.
After the mode is chosen, a trigger condition must be set. A trigger condition can range from simple (such as triggering on a rising or falling edge of a single signal), to the very complex (such as configuring the analyzer to decode the higher levels of the TCP/IP stack and triggering on a certain HTTP packet).
At this point, the user sets the analyzer to "run" mode, either triggering once, or repeatedly triggering.
Once the data is captured, it can be displayed several ways, from the simple (showing waveforms or state listings) to the complex (showing decoded Ethernet protocol traffic). The analyzer can also operate in a "compare" mode, where it compares each captured data set to a previously recorded data set, and stopping triggering when this data set is either matched or not. This is useful for long-term empirical testing. Recent analyzers can even be set to email a copy of the test data to the engineer on a successful trigger. A data set (or dataset) is a collection of data, usually presented in tabular form. ...
Uses Many digital designs, including those of ICs, are simulated to detect defects before the unit is constructed. The simulation usually provides logic analysis displays. Often, complex discrete logic is verified by simulating inputs and testing outputs using boundary scan. Logic analyzers can uncover hardware defects that are not found in simulation. These problems are typically too difficult to model in simulation, or too time consuming to simulate and often cross multiple clock domains. Integrated circuit of Atmel Diopsis 740 System on Chip showing memory blocks, logic and input/output pads around the periphery Microchips with a transparent window, showing the integrated circuit inside. ...
Boundary scan is a method for testing interconnects (thin wire lines) on printed circuit boards. ...
Field-programmable gate arrays have become a common measurement point for logic analyzers. An Altera Stratix II GX FPGA. A field-programmable gate array is a semiconductor device containing programmable logic components called logic blocks, and programmable interconnects. ...
Probes Today, the most common method of data capture for logic analyzers is through a probe. A logic analyzer can measure anything electronic if it has the proper probe connected. Mostly logic analyzer measure data buses. The probes try to tap into the electronic signals being passed through a data bus or wire. Logic analyzer probes are mostly made by third parties like: FuturePlus Systems, Nexus Technologies, Corelis.
See also A bus analyzer is a computer bus analyzation tool, often a combination of hardware and software, used during development of device drivers for a specific bus and for reverse engineering of devices by reading and interpreting bus traffic. ...
External Links - Agilent
- Tektronix
- FuturePlus.com Channel Partner with Agilent and Embedded Tools Partner with Tektronixen:Логический анализатор
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