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1、第9章 单片机应用系统设计（The ninth chapter is about the design of MCU application system）In this paper, the contribution of butterfly pilesPpt documents may experience poor browsing on the WAP side. It is recommended that you first select TXT, or download the source file to the local view.The ninth chapter is
2、the design of SCM application systemThe focus of this chapter: this chapter focuses on the design of anti-jamming technology of singlechip application system process commonly used in MCU control system 9.1 reliability and anti-jamming 9.2 logic level conversion technology summary of this chapter 9.3
3、 system designHttp:/Nine point one9.1.1Reliability and anti-interferenceSources and types of interference1) according to the sources of interference, interference sources can be divided into internal interference and external interference. According to the sources of interference, interference sourc
4、es can be divided into internal interference and external interference. Internal interference is a variety of disturbances caused by various components in the computer control system, including fixed interference and transient interference. All kinds of interference, including fixed interference and
5、 transition interference. External interference and external interference are those that are independent of the system structure. External disturbances are interference with the structure of the system, determined by the conditions of use and the external environmental factors. It involves interfere
6、nce from natural disturbances and environmental disturbances. It includes natural disturbances and environmental disturbances, mainly from nature as well as surrounding electrical equipment. Electrical equipment from nature and around it.Http:/2) according to the characteristics of interference can
7、be divided into DC interference, AC interference and random interference. Three, according to the characteristics of interference can be divided into DC interference, and so on. DC interference DC interference is usually caused by thermoelectric effect and electrochemical effect, and the DC DC inter
8、ference is usually caused by thermoelectric effect and electrochemical effect, in the form of flow or DC voltage. In the form of flow or DC voltage. AC AC interference jamming is one of the most common interference, caused by alternating current induction, AC interference is a most common disturbanc
9、es, caused by AC induction, because the channel is often stray electric and magnetic field distribution of many places, often in the process of channel stray electric and magnetic field distribution of many places, when the parallel feeder signal wiring with the power line in the wire slot, and powe
10、r lines in parallel wiring wire slot, the coupling into the channel is particularly evident. As obvious. Random interference random interference is usually transient, peak or pulse form, random interference is generally transient, peak or pulse form, cause intermittent work by inductive loads, the i
11、nterference caused by large amplitude, short time, continuous work load, the interference of short time, amplitude large, it will cause great harm to the system. Cause great harm to.Http:/3) the interference can be divided into normal interference and common state interference according to the inter
12、ference. Normal interference normal interference is the interference superimposed on the signal being measured. Normal interference is the interference that is superimposed on the signal being measured. The measured signal is usually a DC or a slow change signal, the signal is usually DC or slow cha
13、nge signal, and the interference is fast, messy, irregular alternating signal. Alternating signal. The common mode interference common mode interference refers to the input circuit of common interference and common mode interference refers to the input circuit of common interference, the interferenc
14、e can be DC, can communicate, can be amplitude range, DC, can also be exchanges, the amplitude of varying size, depending on the environment and equipment grounding. Common mode interference is also called common mode interference. Grounding of the environment and equipment. Common mode interference
15、 is also called common mode interference.Http:/9.1.2 studies the importance of anti-jamming technology, the consequences of interference: the consequences of interference: data acquisition error increases, data interference changes, 9.1.3 microcontroller system reliability design 1.Reliability desig
16、n task internal factors: (1) internal factors: mainly refers to the impact of single-chip system work, including components themselves, system structure design and installation and debugging and other factors. The device itself, system structure design and installation and debugging, and other facto
17、rs. Performance and reliability of components. Performance and reliability of components. System structure design. System structure design. Installation and debugging. Installation and debugging.Http:/(2) external factors: mainly refers to the external environment of the system of single-chip microc
18、omputer operating system external factors: influential factors. Influential factors. The influence of external electrical conditions, such as the stability of the power supply voltage, external electrical conditions, such as the stability of the power supply voltage, the strong electric field and ma
19、gnetic field, etc. External space conditions, such as temperature, humidity, air cleanliness, etc. External space conditions, such as temperature, humidity, air cleanliness, etc. External mechanical conditions, such as vibration, shock, etc. External mechanical conditions, such as vibration, shock,
20、etc.Http:/The general design method of component level reliability measures: 2. reliability components are basic components of SCM system, (1) component level reliability measures: components are basic components of the SCM system, the performance and reliability of components is the basis of the ov
21、erall performance and reliability. The performance and reliability of components are the basis of overall performance and reliability. Strict management of the purchase, storage and transportation of components. Strict management of the purchase, storage and transportation of components. Aging, scre
22、ening and testing. Aging, screening and testing. Derating. Derating. Select components with high integration. Select components with high integration.Http:/(2) the reliability measures of components and system level reliability measures of reliability technology components and system level component
23、s and system level operation refers to the functional components or the whole system in the design, manufacture, operation refers to the functional components or the whole system in the design, manufacture, testing and other aspects the reliability measures taken. Reliability measures. Redundancy te
24、chnology, EMC design, information redundancy technology, time redundancy technology, automatic fault detection and diagnosis technology, software reliability, technology failure Insurance TechnologyHttp:/The anti-interference technology reliability of 9.1.4 single chip microcomputer control system i
25、s an important performance index of SCM system. Reliability is an important performance index of single chip microcomputer system. Single chip microcomputer system where the interference is the main factor affecting reliability. The various disturbances are the major factors affecting reliability. I
26、nterference refers to other electrical signals superimposed on the supply voltage or the normal operating signal. Interference refers to other electrical signals superimposed on the supply voltage or the normal operating signal. There are many sources of interference: power grids, space electromagne
27、tic fields, input / output channels, and so on. There are many sources of interference: power grids, space electromagnetic fields, input / output channels, and so on. The consequences of interference will affect the accuracy of information transmission; will affect the correctness of the information
28、 transmission; normal operation to disrupt the program; the normal operation to disrupt the program; the program fly away or into the dead cycle; make the program fly away or into the dead cycle may damage the chip components. Components that may damage the microcontroller. To solve the interference
29、 problem from two aspects: one is to try to cut off the interference channel, solve the problem of interference from two aspects: one is to try to cut off the interference channel, reduce the interference effect; two is to enhance the anti-interference ability of the microcontroller itself. Interfer
30、ence influence; two is to enhance the anti-interference ability of SCM itself.Http:/1. hardware anti-interference technology, power supply refers to the power supply used by scm. (1) the power supply refers to the power supply used by the microcontroller. Filtering and shielding methods are used. 1)
31、 using filtering and shielding methods.Filtering and shielding of AC power supplyHttp:/2) adopt isolation and AC voltage regulation measures. Adopt isolation and AC voltage regulation measures.AC power isolation, filtering, AC power isolation, filtering, voltage regulation and shieldingHttp:/3) the
32、use of decentralized DC power supply. The use of decentralized DC power supply mode.Decentralized DC power supply modeHttp:/4) with high anti-interference power supply and interference suppressor: the anti-jamming power with high anti-interference power supply and interference suppressor: such as in
33、terference voltage stabilizing transformer, purifying AC regulated power supply (products, such as interference voltage transformer, purifying AC regulated power supply (power regulator), switching power supply, reverse forward converter), switching power supply regulator adopts flyback converter),
34、switching power supply, the flyback converter with the spectrum equalization principle of interference suppressor made etc. A jamming, suppressor, etc. The signal line can not be in parallel with the AC power supply; 5) the signal line can not be laid in parallel with the AC power source, as far as
35、possible from the AC power line and the high-power electrical equipment. High power electrical equipment.Http:/(2) analog input channel, analog input channel interference signal, there are two kinds of normal interference and common touch interference. There are two kinds of interference signals in
36、analog input channel: normal interference and common disturbance. Suppression of normal interference: 1) suppression of normal interference: normal interference is an interference signal superimposed on the measured signal. Signal.Normal interference signalHttp:/Enter the filter in the input circuit
37、. Commonly used dual T filter, as shown in Figure 9-5, access filters in the input circuit. Commonly used dual T filter, shown in Figure 9, this is a bandpass filter, shown in this is a band pass filter, for high-frequency and low-frequency interference have inhibitory effect. Effect。Double T filter
38、Http:/Using double integral A/D converter, because of its integral work, it has a double integral A/D converter. Because of its integral work, the A/D converter can eliminate the interference of high frequency. Eliminate the effect of high frequency interference. The access optical coupler can effec
39、tively block the transmission of noise. Access to optical coupler can effectively block the transmission of noise. The voltage signal transmission is changed into current signal transmission method, and the voltage signal transmission is changed into current signal transmission mode, so that anti-in
40、terference ability can be improved. Shielding measures can also be applied to transmission lines. Shielding measures may also be adopted for transmission lines.Current transmission modeHttp:/2) suppression of common mode interference. Common mode interference is the suppression of common mode interf
41、erence on two lines of a signal. Interference signal. Interference signal. This is because there is a potential difference between the ground of the tested signal and the ground terminal of the single chip microcomputer system. There is a certain potential difference between the ends.Common interfer
42、ence signalHttp:/Methods: to suppress common mode interference suppression method of common mode interference: using the double input differential amplifier, differential amplifier, the amplifier adopts double input with high cmrr. System ratio. Isolation method. Eliminate common mode interference c
43、aused by inadequate common ground. Isolation method is adopted. Eliminate common mode interference caused by inadequate common ground. For example, a measuring amplifier with photoelectric isolation is used. If the signal transmission distance is long. Measuring amplifier with photoelectric isolatio
44、n. If the signal transmission distance is long. It can be transmitted by frequency signal, so it is easy to implement photoelectric isolation. It is transmitted in frequency signal to facilitate photoelectric isolation.Http:/(3) transmission line 1) when laying lines to make the measured signal line
45、, control signal line and the AC power line, when laying lines to make the measured signal line, control signal line and the AC power line, electrical equipment, electrical equipment, power line driving distance. Electrical equipment drive line, high power electrical equipment, leave a certain dista
46、nce. 2) signal line using twisted pair, make the space electromagnetic field signal line in a small loop using twisted pair, the induced electromotive force offset; induced electromotive force also can offset each other; use the shielded wire or metal tube through the signal line, shielding layer or
47、 one end of a metal pipe well grounded. One end of the metal tube, shielding layer or metal tube is well grounded.Http:/3) float the long line through an optical coupler. This can be effectively eliminated by floating the long line from the optical coupler. The interference of the transmission line
48、into the microcontroller. The interference of the transmission line into the microcontroller.Optically coupled floating processing of a transmission lineHttp:/4) in order to avoid signal distortion. For long line transmission, pay attention to impedance matching. Impedance to avoid signal distortion. For long line transmission, pay attention to impedance matchin