The relationship between logic analyzer and oscilloscope
The test object of a logic analyzer is digital information in a digital system. To meet the detection requirements of modern data domains, logic analyzers should have high sampling rates and a sufficient number of input channels. Based on the concept of virtual instruments, this article mainly discusses the design principles and methods of a 400MHz/102-channel logic analyzer based on PC586, focusing on the system control circuit design and system software design.
Timing and protocol are the two key points in digital system debugging, and they are also where the logic analyzer can best play its role. How to use a logic analyzer to quickly complete wiring configuration and collect data?
The logical relationship of digital systems is the key in the communication research and development process. It directly affects whether the entire equipment system can work normally. Although oscilloscopes can also perform some digital signal analysis, they are limited by the number of channels (generally only 4 channels) and storage depth (small). The logic analyzer can reach 34 channels, and the recording depth can reach up to 2G. Together with the data compression algorithm, it greatly improves the efficiency of engineers' test timing analysis.
In the field of electronic testing, the oscilloscope is the earliest testing equipment. It originated from the principle of radar scanning. The collection and reproduction of signal waveforms originated from the traditional testing basis of analog signals and analog circuits. With the development of digital technology, digital signal testing is becoming more and more important. The earliest digital signal testing was often done by oscilloscopes. Later, timing analyzers and status analyzers appeared to analyze and test multiple channels from the perspective of timing and status. Digital signal.
Since the timing analyzer and state analyzer at that time were expensive, the concepts of the two on the market were very good, but their impact was not great and the test range was very narrow. With the development of digital test technology, logic analyzer applications that integrate digital timing and state analysis have emerged.
Since its birth, logic analyzers often give people three impressions: ① expensive and troublesome to operate; ② high requirements on users; ③ functions are similar to those of oscilloscopes, but with additional channels and some timing functions.
In fact, logic analyzers and oscilloscopes are now being integrated, and there are also major differences in testing principles. Coupled with the development of IT technology, acquisition-type virtual logic analyzers based on computer interface technology and processing technology have emerged. Logic analyzers Costs have gradually been reduced and they have entered ordinary research laboratories. Logic analyzers, like oscilloscopes, have gradually become basic testing tools.
A logic analyzer is an instrument that uses a clock to collect and display digital signals from test equipment. Its main function is to determine timing. Since the logic analyzer does not have many voltage levels like the oscilloscope, it usually only displays two voltages (logic 1 and 0). Therefore, after setting the reference voltage, the logic analyzer passes the measured signal through the comparator to determine whether it is higher than the reference voltage. The voltage is High, the voltage is lower than the reference voltage is Low, and a digital waveform is formed between High and Low.
