Proper selection and use of logic analyzers

First, the development of logic analyzer

Since the early 1970s, microprocessors have been developed, with 4-bit and 8-bit buses. The dual-channel input of traditional oscilloscopes cannot meet the 8-bit byte observation. Testing of microprocessors and memories requires different time and frequency domain instruments. Digital domain test equipment came into being. Soon after HP introduced the state analyzer and Biomation introduced the timing analyzer (the two are very different at the beginning), users began to accept this digital domain test instrument as a means of solving the digital circuit test, and soon the state analyzer and timing The analyzers are combined into a logic analyzer.

In the late 1980s, logic analyzers became more complex and, of course, more difficult to use. For example, multi-level tree triggering is introduced to cope with complex events such as IF, THEN, and ELSE. This type of combination trigger is necessarily more flexible and at the same time not as easy to grasp as most users.

Logic analyzer probes are increasingly important. Probe problems arise when clips are used to clamp 16 pins on a perforated component and pins with a 0.1" gap on a dual in-line component. Today's logic analyzers provide hundreds of jobs at 200 MHz. The channel signal connection on the channel is a real problem. Adapters, clips and auxiliary claw hooks are various, but the good way is to design an inexpensive test fixture. The logic analyzer is directly connected to the fixture to form a reliable and compact. s contact.

Today's development trend

The basic orientation of logic analyzers has found a solution in the continuous integration of computers and instruments in recent years. Tektronix's TLA600 Series logic analyzers focus on the ability to guide and develop, that is, how the instrument behaves and how to construct a distinctive structure. Guided by Microsoft's Windows interface, it is very easy to drive. Improving signal discovery capabilities necessarily involves changes in instrument structure. Focus on time-related data in all data to be processed, and different types of information are displayed in multiple windows. For example, for a microprocessor, Zui can observe both timing and state and disassemble source code, and the cursors on each window are tracked to each other.

Regarding triggering, it is always a problem in traditional logic analyzers. The TLA600 Series Logic Analyzer provides the user with a trigger library that simplifies the setup of complex trigger events and ensures that you focus on solving test problems without having to spend time adjusting the logic analyzer's trigger settings. The library contains a number of easy-to-follow trigger settings that can be used as trigger starting points that typically need to be modified. The need for special triggering capabilities is only part of the problem. In addition to being triggered directly by an error event, the user also wants to observe the signal from the past time period to find out the source of the error and its relationship. Fine triggering and deep memory improve lead triggering.

Using Windows on a PC platform, in addition to providing many well-known benefits for the majority of users, as long as the right software and related tools are given, remote control over the Internet can be used to extract source code and symbols from the target file format. Microsoft's CMO/DCOM standard, and the processor can run a variety of control operations.

Second, the choice of logic analyzer

If the digital circuit fails, we generally consider using a logic analyzer to check the integrity of the digital circuit. It is not difficult to find the fault; but in other cases, do you consider using a logic analyzer? For example: * How to observe the test system when executing our pre-programmed program, is it really implemented in accordance with our designed program? If we write to the system (MOV A, B) and the system is executed (ADD A, B), what are the consequences? The second point: how to really monitor the actual working state of the software system, instead of setting the breakpoints by means of DEBUG, etc., after viewing some of the preset variables or the data in the memory is the value we expected in advance. Here we have third, fourth and many other issues to be resolved.

Usually we divide the digital system into hardware and software. When developing and designing these systems, we have a lot of things to do, such as the preliminary design of the hardware circuit, the software development and preliminary programming, the debugging of the hardware circuit, the debugging of the software, As well as the finalization of the system of Zui, etc., almost every step of the work requires the help of a logic analyzer, but in view of the economic strength and personnel status of each unit, and in the use of many systems, it is not necessary. Do each of the above sections, so we divide the use of the logic analyzer into the following levels:

* Levels: Just look at some common faults in the hardware system, such as the waveform of the clock signal and other signals, whether there are any faults in the signal that seriously affect the system's glitch signal;

The second level: a good analysis of the timing of each signal of the hardware system, so that Zui can make good use of system resources and eliminate some faults that can be analyzed by timing analysis;

The third level: the analysis of the hardware to the implementation of the software to ensure that the written program is completely executed by the hardware system;

The fourth level: the software implementation needs to be monitored in real time, and the software can be debugged in real time.

The fifth level: the systematic analysis of the software and hardware of existing customer systems is required to achieve a comprehensive and thorough understanding of the software and hardware systems of existing customer systems.

For the above several levels of requirements, we can see that they do not all need very high-end logic analyzers. For *level users, they can solve problems even with a better-functioning oscilloscope. Several levels of use, the corresponding instrument can be selected when selecting the instrument. In fact, logic analyzers also have several levels, they have:

1, ordinary 2 ~ 4 channel digital memory, such as TDS3000 series (plus TDS3TRG advanced trigger module), using some of its advanced trigger functions (such as pulse width trigger, runt trigger, certain sum between each channel, Or,, or, or XOR triggers, you can find the signal we want to see, find and eliminate some faults, and the oscilloscope function can be used for other purposes. Here we only use the additional functions of an oscilloscope. It can be said that this way is the way zui saves.
2. When the number of channels of the oscilloscope is not enough, you can also choose some multi-channel timing analysis instruments with simple timing analysis functions, such as the early logic analyzer and the mixed signal oscilloscope currently available on the market, such as Agilent's 546× ×D oscilloscope.
3, some functions are relatively simple, the speed is not particularly fast computer card type, based on Windows, most of the functions are completed by software virtual instruments, such products are produced in many domestic manufacturers.
4, sampling rate, trigger function, analysis function are very powerful non-expandable fixed machine. Example TLA600 series.
5, more powerful and more expandable modular plug-in machine; for different users, you can choose different grades of instruments for your needs.

Some technical indicators of the logic analyzer:

1. Number of channels of the logic analyzer: Where a logic analyzer is required, to fully analyze a system, all signals that should be observed should be introduced into the logic analyzer, so that the number of channels of the logic analyzer should be at least Yes: Word length of the system under test (number of digital buses) + number of control buses of the system under test + number of clock lines. This requires at least 68 channels for a 16-bit machine system. At present, the number of channels of mainstream products of several manufacturers is more than 340 channels. Example Tektronix et al.
2, timing sampling rate: in the timing sampling analysis, to have sufficient timing resolution, it should be high enough timing to analyze the sampling rate, we should know that not only high-speed systems require high sampling rate (see table below) The sampling rate of current mainstream products is as high as 2Gs/S. At this rate, we can see the details in 0.5ps time.
Below is a list of some of the most common chips' operating frequencies and setup/hold times. We can see that even though they operate at low frequencies, the resolution required in Timing is high.
3. State analysis rate: During state analysis, the logic analyzer samples the reference clock with the working clock of the object under test (the external clock of the logic analyzer). The high rate of the zui of this clock is the high state analysis rate of the logic analyzer. That is, the logic analyzer can analyze the fast operating frequency of the system zui. Current mainstream products have a timing analysis rate of 100MHz, and Zui can be as high as 300MHz or higher.
4. Memory length per channel of the logic analyzer: The logic analyzer's memory is used to store the data it samples for comparison, analysis, and conversion (such as converting the captured signal to a non-binary signal [ Assembly language, C language, C++, etc., the benchmark when selecting the memory length is "greater than the length of the zui chunk that the system we are about to observe can be divided by zui.
5. Logic analyzer probe: The logic analyzer is connected to the device under test through the probe. The probe acts as a signal interface and occupies an important position in maintaining signal integrity. Logic analyzers are different from digital oscilloscopes in that although amplitude variations relative to the upper and lower limits are not important, amplitude distortion must be converted to timing errors. The logic analyzer has a probe with tens to hundreds of channels, and its frequency response ranges from tens to hundreds of MHz, ensuring that the relative delay of each probe is small and the distortion of the amplitude is low. This is a key parameter for characterizing the performance of a logic analyzer probe. Agilent's passive probes and Tektronix's active probes are representative of the high-end probes of logic analyzers.
The strength of logic analyzers is the ability to gain insight into the timing relationships of signals in many channels. Unfortunately, if there is a slight difference between the channels, the timing deviation of the channel will occur. In some models of logic analyzers, this deviation can be reduced to small, but there are still residual values. General purpose logic analyzers, such as Tektronix's TLA600 or Agilent's HP16600, have a time offset of approximately 1 ns in all channels. Therefore, the probe is very important. For details, please refer to the “Test Accessories and Connecting Probes”.

a) The resistive load of the probe is the magnitude of the shunting effect on the system current in the access system of the probe. In the digital system, the current load capacity of the system is generally above several KΩ, and the effect of the shunting effect on the system is generally It can be neglected that the impedance of several popular long logic analyzer probes is generally between 20 and 200KΩ.
b) Capacitive load of the probe: The capacitive load is the equivalent capacitance of the probe when the probe is connected to the system. This value is generally between 1 and 30 PF. In the current high-speed system, the capacitive load has a great influence on the circuit. For resistive loads, if this value is too large, it will directly affect the shape of the signal "edge" in the whole system to change the nature of the whole circuit, changing the real-time performance of the logic analyzer to the system observation, so that we are not seeing the system. Original features.
c) The ease of use of the probe: refers to the difficulty of the probe when it is connected to the system. As the density of the chip package is getting higher and higher, various package forms such as BGA, QFP, TQFP, PLCC, SOP appear. The IC's foot pitch zui has reached 0.3mm or less. It is very good to take out the signal, especially the BGA package. It is really difficult, and the size of the discrete device is getting smaller and smaller, and the typical has reached 0.5mm × 0.8. Mm.
d) Compatibility with the debug section on existing boards.
6, the openness of the system: As the voice of data sharing is getting higher and higher, the openness of the system we use is becoming more and more important. The operating system of the current logic analyzer has also evolved from the past dedicated system to using Windows. Interface, so we are very convenient when using.

summary

If you have digital logic in your work, you have the opportunity to use a logic analyzer. Therefore, you should choose a logic analyzer that meets the functions used and does not exceed the required functions. Most users will find an easy-to-operate instrument that has fewer steps in function control, fewer menus, and less complexity.
On the other hand, if you need to use the zui fast and zui large analytical logic analyzer, there are ready-made solutions. This novel instrument has almost no channel-to-channel delay and probe loading effects. If you are slightly overwhelmed, you may have to spend tens of thousands of dollars in tuition to gain experience.
It is really important to be able to capture the signal. When you know that the data being captured is useful data, you rely on the power of the logic analyzer.

We are a chinese origin manufacturer , we majored in producing rubber products for almost 10 years , which allows us to offer a wide range products for you . Our products now are widely used in clinical injection, transfusion and other packaging. We now have a  100-100000 class cleaning workshop which meets the GMP standard. From input to output, we have a strict quality control throughout the whole production line. We have full test instruments and tools according to the standard documents. 

Butyl Rubber Stopper For Film Coated

Butyl Rubber Stopper For Film Coated,Stopper For Film Coated,Silicone Rubber Stopper,Butyl Bottles Silicone Rubber Stopper

SUZHOU CRH PHARMACEUTICAL TECHNOLOGY CO.,LTD , https://www.crh-health.com