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Huawei internal hardware development and design process

2020-12-08 01:48:08 ybhuangfugui

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source |  Big fish robot

Huawei's internal hardware development and design process

2007 year , With 2 Years of work experience. Go to a small company for an interview . At that time, the written examination was finished , The other side was very impressed with me . But then he said :“ I need to recruit one , I've been in a big company , It's better to know the hardware development process and specification . Although you answer the question well , But we need an experienced one , It's better to have been in Huawei .”

at that time , I was thinking. “ What are Huawei's specifications and processes ”. Then I went to Huawei , I can't think of the same hardware that Huawei has developed , Share with you .

NO.1 writing files , review To examine , set up meter

When I was just on the job , Three people make a circuit board . Although the circuit is more complicated , There are still some surplus manpower . therefore , I was assigned to write a PCI turn UART The logic of .

I was a new employee , Also eager to show themselves , Take advantage of the weekend , It took about a week , Just write the code , It's time to simulate . I thought my tutor and supervisor would praise , The results did not , He said :“ Why didn't you call people to discuss ? And then write a plan , review ? And then the handwritten code ?” I didn't understand , Think I've done it all by myself , Why do we have to work so hard to attract people ?

After reflection, we found the following problems :

First of all 、 From a supervisor's point of view , I don't know the new employee's personal ability , You can make it clear what you're doing , He was relieved .

second 、 From the company's point of view , There is a process to ensure project delivery . Then you don't rely too much on someone's personal abilities , Anyone's leaving , Will not affect the delivery of the project . This is also the most remarkable thing about Huawei , Break down complex projects very finely , It doesn't take special people to deliver the project . That's why Huawei's engineers earn from Cisco N One of the points .

Third 、 From the perspective of effect , After all, one's thoughts are limited , The process of documenting ideas , It's the process of organizing ideas ; The process of discussion , It's collecting processes that you didn't think of . Formal review , It's the process of reaching an agreement . Discuss ahead of time , Get people involved in the design , It's better than you've designed it , It's much better to be pointed out as a fatal problem .

It's because Huawei broke up a job , So communication , file , review , Discuss , Become very important . The disadvantages of this working mode , It's also obvious , High communication cost , Low work efficiency .

NO.2 The composition of the hardware field

Inside Huawei , There are so many roles for people . Hardware people are on the product development stage , End to end responsible for . Be a hardware engineer , You can cover the most fields , At the same time, it is also the most complicated work , Contact people most , The most skilful job .

But also because someone is in charge of painting PCB、EMC、 Power Supply 、 Logic , What hardware engineers should have done . Then the hardware engineers will be useless , become “ Connect the line ”.

It's not , It's because everyone is a small field , No one is in charge of , So the role of a good hardware manager is very important , Is a key role across all areas and processes . As the original Huawei internal forum has a metaphor , Hardware engineers are more like processors “Cache”, It's a transit station for all links . Big companies divide the division of labor into so many different parts , It is also to prevent a certain group from mastering too many core technologies of the company , I went out alone .

NO.3 Huawei's process

In fact, Huawei's process , A lot of people know that IPD The process is from IBM To the , I personally understand :IPD Processes have been mutated in Huawei , Combined with Chinese characteristics , Huawei's enterprise characteristics have been adapted and optimized . If Huawei applies it rigidly IBM This process of , And certainly not so successful .

So summarize Huawei's hardware development process :

Demand analysis → overall design → Thematic analysis → Detailed design → Logic details → Schematic diagram →PCB→ Inspection → Glue logic → Cast board → Production trial production → Back board debugging → unit testing → Professional experiments → System joint debugging → Small batch trial production → The hardware is stable → maintain .

The essence of the process is , This link is done well , Go to the next step . In fact, all the links are not very different from other companies , But we have strictly grasped the assessment conditions for entering the next link . What bothers hardware engineers most is “ There's no node with ’ Cast board ’ Corresponding ”.

Huawei supports IPD The system of process is PDM( Also known as slow climbing )

PDM The Chinese name of "product data management" (Product DataManagement).PDM It is used to manage all product related information ( Include part information 、 To configure 、 file 、CAD file 、 structure 、 Authority information, etc ) And all product related processes ( Including process definition and management ) Technology . All the device information of Huawei , Product parts , Tools , file , Schematic diagram ,PCB, Logic code and so on exist in this system . But the system is too complex , Actually, it's hard to use , File with the server 、SVN file 、 It's easy to confuse .

NO.4 normalization

1

Device normalization

Hardware engineers generally understand , On a board , Choose as low-cost devices as possible , Choose fewer types of devices , Convenient for centralized purchasing , It's also easy to process . But other companies may not be as meticulous and rigorous about device normalization .

First of all , Because Huawei uses a wide range of devices , So if you reduce a device code , The revenue is from 100000 yuan to several million yuan , And other companies may not be able to achieve this high revenue . So if you can reduce one code , Prefer devices that may cost more . But this also needs to be based on the annual device direct cost benefit * Number of devices shipped , And coding costs + Processing cost differences , For comparison . But after the device is normalized , The price of the device can be renegotiated with the supplier , The payoff is iterative . therefore , Even if it's the dominant cost , It also tends to get rid of the conclusion of device normalization . for example , Gradually removed 5% Precision resistance , Normalize to 1%.

second , Device normalization , All of them need special analysis . Because there are also engineers who want to normalize , The circuit principle is not fully analyzed , The resulting normalization brings about “ Problem introduction ”. therefore , At that time, my department had a form ,“ Device normalization analysis .xls” Of excel form , Put every device , The original model , Normalized selection , The reason for the change , Record and analyze the causes . One is to let every employee who does normalization fully consider the analysis , Second, all problems are recorded , Easy to review , Third, something goes wrong , It's good to play .

2

Veneer normalization

In addition to device normalization , A higher level of normalization , It's the normalization of the single board .( The concept of veneer , Let me clarify a little bit , When I first arrived at Huawei , I think it's a strange word . Because of the communication equipment , It's all frames , Backplane , Add the circuit board of each function module , The circuit of each function module is called “ Veneer ”, Hardware Engineer , It's also called “ Single board hardware ”)

The benefits of veneer normalization , First of all, there are few kinds of circuits , There are three advantages to having fewer types of circuits :

First, the production cost is reduced ;

Second, the cost of hardware maintenance is reduced ;

Third, the cost of software development and maintenance is reduced .

First of all 、 The precondition of board normalization is processor normalization . Actually , Some of Huawei's products are not well done ,X86、MIPS、ARM、PPC Use it all over , So a hardware platform , Need to be equipped with a variety of software personnel , The operating system does N set ,VxWorks and Linux,BIOS All kinds of accessories .

second 、 Normalization of veneers , Pay attention to the derivation of products . The first version of the board on the frame to achieve the function , If subsequent products can be used , It should be directly available , No need to redevelop . If you don't pay attention to this , The first version of the board , By the second edition , Find that you can't borrow from each other . In turn, , Modify the first version of the board , To adapt to the new version . Sometimes the problem is worse , It's completely incompatible , We have to redevelop . Board planning is very important .

Third 、 When the veneer is normalized , Although the circuit is partially compatible with , But frame members are not compatible . For the allocation of marketing personnel , There are still two configurations . The same is a failure .

3

Platform normalization

So if we find that the architectures of different hardware platforms are the same , The function is similar to . Then frames can be normalized . Only need to make different circuit function modules , Can achieve different functional requirements .

But different hardware forms have their own significance , If forced to be one , The market may not accept that this happens . For example, use an operator's platform to unify the products of an enterprise application or a home application , It may not be possible to succeed .

4

Network architecture normalization

This is what I thought of myself , As early as 08 In the year , Huawei is talking about “ Cloud management end strategy ” 了 , At that time, I didn't quite understand . When we are an operator platform Department , Follow “ The server ” When our departments merged , Seems to understand something .

When X86 When the processor is powerful enough , All the operations , Whether it's the best value for money or not , All sent to the cloud for processing , So all the intermediate storage and computing doesn't matter . So the whole network structure , It's the terminal + The Conduit + Cloud storage and cloud computing .

NO.5 Thematic analysis

I think a lot of hardware engineers have a mistake , I feel that my core competitiveness lies in the ability to use several software (cadence、Protel), Draw a schematic diagram , Drawing a picture PCB. My early job was like this , The greatest skill is to draw a gourd like a gourd , copy Demo plate , Copy the old circuit , If there's a new circuit design , Generally, the circuit is drawn first according to the reference circuit , And then through debugging , To try , Problems encountered , Then solve the problem .

So my idea now is , The most valuable thing about hardware engineers is that they understand the principles of hardware , Know circuit analysis , The principle of analog electricity, digital electricity , Electromagnetic field theory , Instead of using drawing software .

So how does Huawei do circuit design ? Why is there a special analysis ? Why do we have to do special analysis in circuit design ?

second 、 When the circuit design process , There are some new problems , Problems that have not been dealt with in the team before , Or think it's the point , The content of the difficulty , Will do a special analysis of this problem point : For example, we made some pairs BIOS start-up , The infrared of the camera LED The driver , Main / standby switching , And so on. , Will analyze a problem point through , And then I'll do the schematic diagram .

Third 、 So when developing hardware ,Demo Just for reference , Every basis comes from datasheet, Besides reading the data book of the chip , Also check out the Corrigendum to the data book errata, check datasheet And Demo It's almost like , If the device has checklist You have to check checklist. Once developed AMD When ,datasheet、Demo、checklist, Three documents can not match . There have been , A more difficult problem to reproduce , Later I checked Errata, It was found that the manufacturer's chip had been upgraded , Fixed a bug, And we're still buying old chips .

Fourth 、 Because the project itself has delivery time requirements , So it is impossible to do every problem thoroughly in a limited time . So here comes the question :

How to do it ? First , Every project has 《 Problem tracking table 》, And the hardware team because of the complexity of things , So use this watch very well , Otherwise, it's normal to lose Dong and Lasi . I used to use this watch to decorate my house . The principle of this watch is very simple , It's the record , Question content , Those responsible , Completion status , Completion time . But as long as you stick with it , You'll find that , You don't lose track of your questions , Things will be more organized , And there will be a sense of accomplishment . After using this watch , After finding the problem , Write it down first , Even if it's not solved now , Then it will identify whether he wants to solve it , When to solve . secondly 、 Questions are prioritized , Any project goes forward with risks , So identify high-risk problems , Prioritize high-risk issues , Keep going with low-risk questions . This is also in Huawei's circuit design “0 ohm ” There is a reason why resistors are used more often , After identifying the risk , But the analysis is not clear , Or there's no time to analyze , We have to do compatible design . Here I have to say with emotion , In your design process , You are careless with , There is no clear analysis of the problem , It's bound to come out in the end .

therefore , stay “ Chrysanthemum factory ” Be a hardware engineer ,“ Thematic analysis ” It's the core of hardware design , Instead of drawing a schematic . Through this method , use 1~2 Do circuit analysis for months , While using 1~2 Weekly time to draw schematic diagram , To replace the , drawing , debugging , Revision , Re commissioning , In the form of revision . Achieve greater, faster, better and more economical results , It's impossible to achieve it at the same time , So it's up to the hardware engineer to make good trade-offs .

NO.6 Special topic research : Device selection specification

One 、 About “ Device selection specification ”:

When I entered Huawei , At that time, the whole company was “ standard ” motion , Write a standard for everything , Everybody writes about norms , What position 、 The performance of 、 The technical level depends on the specification .( Large companies KPI To guide , It's easy to make “ motion ”). So then , According to the type of device , Many people have written various device selection specifications . at that time , When reviewing the schematic diagram , What I hear most is “ That's what the specification says ”, There are some problems :

1、 People who write norms are not necessarily high-level , Or it's not detailed , If there is a mistake, it is even more harmful .

2、 Norms sometimes inhibit the developer's thinking , Everything follows the rules , Not necessarily suitable for actual design scenarios ; For example, I need low-cost design , But the code emphasizes high quality , It doesn't necessarily apply .

3、 When there are norms , It also causes some developers not to think , For example, the crystal oscillator is required to be in 50MHz above , discharge pF The power filter is carried out by the capacitor of level 1 , And below 50MHz You don't have to . People don't want why , Naturally, I don't know why ; Another example is network port transformer protection , Indoor and outdoor , According to EMC Standard design requirements , Just follow the picture ; But few people think why , I don't know what the test results are , When we encounter difficulties, we will be blind . It is true that sometimes it improves work efficiency and product quality , But tools are also developed , The more people degenerate , This is inevitable .

4、 Some of the device selection , It's not suitable for writing specifications , Because devices are developing so fast , It's possible to wait for you to write it properly , The devices are out of date . for example : stay X86 After the processor entered the field of communication , Processor selection specifications are redundant .

Norms do bring benefits . however , Not all jobs are suitable to be constrained by specifications . Hardware engineers need to be able to jump out of “ Reference circuit ”、 Jump out of “ standard ”, Think about problems and design from the principles .

Of course, norms are a very useful tool , It's a lot of theoretical analysis + Experience accumulation + The essence of practice data . I think the norm I saw most at that time , yes 《 Derating specification for device selection 》, It's based on a lot of experiments , Actual case , When summarizing the device selection , What needs to be considered .

for example : When selecting aluminum electrolytic capacitor , It is necessary to consider that the steady-state operating voltage is lower than the rated withstand voltage 90%; And tantalum capacitors , Steady state derating is required in 50%; And ceramic capacitors , Steady state derating is required in 85%; Because we consider the utility mode of some devices 、 The worst environment ( The high temperature 、 low temperature 、 Maximum power consumption ), Difference between steady state power and transient power …… And so on .

Two 、 Factors to be considered in device selection :

In Huawei PDM On the system , Devices have a preferred level “ optimization ”“ Not preferred ”“ No election ”“ Terminal only ” Wait a few levels . Engineers can intuitively feel whether the device is optimized according to this optimization level .

Then the preferred level of the device , What factors have been considered ?

1. Availability : In particular, manufacturers like Huawei , There are a lot of products to ship . Careful selection of devices whose life cycle is in decline , It is forbidden to use the devices that are out of production . I 2005 When I was in, I designed a circuit , Design is copying other people's circuits , As a result, when processing, it was found that the device could not be bought at all , Because the device is out of production , You can only buy refurbished devices in the electronics market . For key devices , At least two brands of models can replace each other , Some also need to consider program level substitution . That's important , If it's an exclusive product , It needs to be reported at all levels , Decision making , Assessing risk .

2. reliability :

Dissipate heat : Power devices are preferred RjA Small thermal resistance ,Tj Package models with higher junction temperature ; Processor selection , When the performance is satisfied , Try to choose devices that consume less power . But if it is Intel Such a monopoly device , You have to put up with , Add radiator , Add a fan .

ESD: The antistatic capacity of the selected components should reach at least 250V. For special devices such as : RF devices , resist ESD Ability at least 100V, It is also required to design anti-static measures .( notes : Huawei has strict requirements , It's forbidden to hold boards in bare hands . I didn't understand , And then I took the team and , Found that brothers spent a lot of time repairing veneers ; Our team is very strict with this , Seems to reduce efficiency , In fact, it can improve efficiency . At least there is no need to always suspect that the device has been damaged by static electricity .)

A higher humidity sensitivity level is considered for the selected components .

Security : The materials used shall be antistatic 、 Flame retardant 、 Rust prevention 、 Antioxidant and safety requirements .

Failure rate : Avoid devices with high failure rates , For example, the labeled dial switch . Try not to be naked Die The device , Easy to crack . Don't choose glass packaged devices . Large package of ceramic capacitors do not choose .

Failure mode : The failure modes of some devices need to be considered , Open or open , What are the consequences , All need to be evaluated . This is also an important reason for careful selection of tantalum capacitors .

3. Productive ability : No package size less than 0402 The device .

Try to choose surface mount devices , Reflow only once , Just finish welding , No wave soldering is required . If some plug-in devices are unavoidable , You need to consider , Can the through-hole reflow soldering process be used to complete the welding . Reduce welding process and cost .

4. Environmental protection : Because a lot of Huawei's products are sent to Europe , So the requirements of environmental protection are also quite strict . Because of the EU's lead-free requirements , Once almost all the hardware engineers of the whole company were doing lead-free rectification .

5. Consider normalization : For example, this device has been used in a product , And when you ship a lot , Sometimes the selection of this device is not very suitable , Will also choose , Because not only can we talk about the cost again by increasing the quantity , You can also safely choose , Because it has been verified in large quantities . That's why we tend to choose mature devices , And carefully choose the reasons for the introduction period and the decline period .

6. Industry management : A big category , for example : Power Supply 、 The clock 、 processor 、 Memory 、Flash And so on, there are special people who plan and coordinate the use of the whole company , Conduct market research ahead of time , analysis , Writing specifications . They will participate in the selection of new devices .

7、 Device Department : I have colleagues in the device department , Can analyze the cause of device failure , Reliability analysis , Camera device X light , Evaluating device life and so on .

8、 cost : If none of these factors are fatal —— The above factors are all floating clouds , Keep an eye on Article 8 .

NO.7 The meeting

The first part of the meeting “ Huawei's Conference ”

1、 First of all, big companies are “ More ”, Because the company is big , Department of more than , The division of human responsibilities is detailed , So one thing , It takes a lot of people to get involved . It's easy to get into wrangles . When I first arrived at Huawei , Very uncomfortable , Document everything , Judge everything , Everything has a meeting ; So I'm not used to so many meetings , It's boring at meetings , All the highest snake eating records were broken during that period .

2、 There is still a person in charge of everything , Huawei gives enough rights to the person in charge , So it can push things forward , Coordinate to resources . For example, marketing is strong enough to drive R & D to meet the needs of customers . The product manager 、 The energy of the account manager is still great , Be able to have a direct dialogue with the R & D minister , Promoting R & D, doing this and that .

3、 All questions will eventually be recorded , track , To guarantee the completion of . That's why even the quality of some devices , When the performance is not enough to satisfy the customer , Customers are also willing to use Huawei's equipment . That's why , Operators like to use Huawei's equipment . There is a problem , It's not sure which one is the problem , Huawei's brothers rushed to . Unicom 2 Personal participation in meetings , Huawei 6 Individuals come to the meeting , Prove by trial , Prove to be Juniper The problem with the equipment . Then give a full report to tell the customer , It's not our problem , This is a XXX The manufacturer's problem .

4、 The forest is big , Any bird will have . So push 、 drag 、 Lai's things happen all the time . This requires a strong and clear performance evaluation system , To guide employees to take the initiative to undertake the task , Not to draw the line . such “ Clear the responsibility ” And it's inevitable . Otherwise, three monks have no water to drink . notes : Huawei's practice of fully discussing everything , It is applicable in the field of telecom operators , In the consumer area 、 Even businesses IT Fields often don't work , Because there is not enough profit margin to support this . So I'm talking about some of Huawei's advantages , HUAWEI mobile phone users do not have to make complaints about me ,:-)

5、 In the course of the meeting , It's often easy for people to get into misunderstandings , Or too divergent , Or too conservative . A meeting in the product definition phase , There are always reminders , Don't converge when you diverge ; In a problem-solving meeting , It's always a reminder , Don't use the past to spread , Focus on the problem . The person who can remind you is very important . Of course, sometimes it becomes mere formality , Friends can see the next case 《 Huawei discusses how to raise Sun Yang's posture 》, There are constant reminders during the meeting , But we are still divergent .

The second part 《 Robert's rules of procedure 》

What is? 《 Robert's rules of procedure 》?

A hundred years ago, there was a good guy , It's called Henry . Martin . Robert , Twenty five years old , The Chinese are called lengtouqing . He graduated from West Point and was ordered to preside over a local church meeting during the civil war . The result? —— Screw up 了 . People have a lot of fun arguing about it , There is no conclusion . In a word, it's a mess . This meeting is worse than not . What about this guy , It's a little bit of a stick . Said I was going to study , Make a rule , Or I'll never have a meeting again . He studied thousands of years of conference discussions , There is a conclusion : Man is probably a very argumentative animal , The most difficult animal to reason with , Once differences arise . It's hard to convince each other by language communication in a short time . Otherwise, a few days and nights of fighting will not have a result . And the more noisy, the more reasonable I feel , He's a fool . So there must be a mechanism for both sides to find common ground and reach a conclusion . He treated the research as a war . Take human nature of argument as enemy . In the end, the young man won .

The result of winning is 1876 Robert's rules of procedure . He published it at his own expense, bought a thousand copies and gave them away everywhere .1915 Robert became a general , He amended the rule . At first, people didn't pay attention to , Can't a little guy with no hair on his mouth . alas , little does one think , That's great , As soon as they put this rule into practice , The fight is over , The meeting went on . Ink bottle , The bench doesn't fly around . As a result, Robert's rules of procedure became the most common rules of procedure in the world .

There are always three questions in a meeting .

One , go off at a tangent : You said jet li , I'm talking about Jackie Chan , I said pig Bajie , You talk about Wen Jiabao and Li Peng . Run out of bounds . And the old people like to show their stories , The beginning , I'll tell you a story , This talk , Let's talk about lunch .

Two , What I say goes : What about this one , It's leaders who love to talk , Who is the leader will talk endlessly , As soon as he spoke, he talked about it all . The second one? , There are some people in the countryside who like to talk . There are also people who never talk ..

3、 ... and , A savage argument : A discussion of the problem , Just say you overcharged five yuan last time , You're not a good boy , Doubt the character of others . One word in a hundred words . Even fight . The meeting can't be held .

Four , interrupt : Don't interrupt someone's proper speech .

One of Robert's rules of procedure is : Host to solve the above problems . But the general enterprise often , When leaders appear , The host is not going to remind the leader ,“ You digress ”,“ You've got your word ”,“ You should not interrupt other people's normal speech ”, This is some of the foreign scientific theories and methods, to China, often do not adapt to the soil of China , Typical cases that can't be copied mechanically .

In fact, Huawei , Has been able to... In most meetings , Make it happen “ go off at a tangent 、 What I say goes 、 interrupt 、 incivilization ” when , There's a host to remind , And pull it back on track . But some meetings don't do it either , such as : The leadership is strong , The leader himself is the host , The host is an apple polisher , Some politically sensitive issues , You can't destroy harmony . I will not elaborate here .

So how does Huawei solve these problems ?

1、“ Customer focus ”, So the leadership is bigger , It's no bigger than a customer , All the demands of customers are promised , It's all done . So everyone is trying to get customers , When people don't have big differences on issues of principle .

2、 Performance orientation , Everything is evaluated according to the results . So on some issues , If the leader puts forward a plan , But when there may be major risks , It is the responsibility of the people below to remind and oppose . Otherwise, it will cause serious consequences , Leaders can't run away , You can fix people down there . They are all grasshoppers tied to a rope . When a colleague puts forward a different opinion from the leader , And when it's valuable , Will recognize this brother from the performance results . It's about educating employees , Encourage objections , Encourage the correction of leaders' mistakes .

3、 Director of Education . Huawei advocates wolf culture , All the supervisors can be promoted to , It's usually wolf like , Be able to speak and speak , verdure , At the meeting balabala a meal , It's also about communicating with employees balabala A good meal for yourself . Then it will be easy to create a monologue , Or off topic . So when it comes to supervisor training , They teach people who lead teams , Be able to listen , Can communicate , When communicating, we should grasp the rhythm and propriety .

The third part Reduce invalid meetings

I used to support CCB Network construction for a period of time , When I first went there , With them IT Planning Department , There was a meeting . at that time , It's typical of a meeting “ What I say goes ”, One of their leaders came over , A cursing :“ How can Huawei's equipment not work , Your Cisco equipment is shit , Your Siemens service is too poor ......”, People from CCB , And the people from the equipment manufacturers have been scolded , Just listen to him complaining , After scolding the equipment manufacturer , Start scolding your employees “balabala”. And then no one knows what this guy wants , The guy couldn't tell me what kind of equipment he wanted , Performance and service . Then he left in anger .

What I say goes 、 go off at a tangent 、 incivilization , These are not fatal , The most lethal is “ Invalid meeting ”. When the leader left , We continue to follow our own ideas , Method , Continue to discuss , And then flowers 2 Minutes to discuss , How to deal with this leader . So what we need in a meeting is , But how to drive effectively is a routine .

So how to do it ?

First of all 、 Regular meetings , There's an agenda . For example, weekly meetings , Arrange the topics of the weekly meeting in advance , It's not very casual to say . Set the agenda , Set a time for each topic , Make sure you don't stray from the subject .

second 、 The meeting should have minutes , The moderator of every meeting , The minutes of the meeting are clear . The minutes of the meeting are very important , It also requires a lot of skill , That is to say, we need to participate effectively in the discussion of the meeting , It's necessary to record the key points , Don't keep a running account .

Third 、 The minutes of the meeting should be divided into :

Conclusion ( The conclusion of the meeting will not be changed at will );

remaining problems ( Must conform to SMART principle );

There has to be someone responsible ;

Time required for completion, etc .

The minutes have templates , Remind everyone that the minutes should conform to SMART principle .

Fourth 、 Keep track of , To close the loop . All the remaining problems , At the next meeting, we will review , See if it's done , There was no delay , Until there's an explanation . Of course , If there is a problem with the return task arrangement , According to the assessment, the problem will also be closed and suspended .

The fifth 、 All decisions need to be justified , It can't be a pat on the head . Because pat your head in advance , I'll pat my thighs afterwards . And then somebody slapped their ass and left . In this way, it will not be decided that the lower level is subordinate to the higher level , The minority is subordinate to the majority . Of course , In this way, there will be efficiency problems , Because some problems will be unclear because of the short-term research , No decision can be made . This is where CCB( This CCB It doesn't mean Construction Bank ,CCB(Change Control Board) stay CMMI(Capability Maturity Model Integration) in , yes “ Change control board ” The meaning of ,CCB It can be done by a team , It can also be done by several different groups , Responsible for making decisions on which proposed requirements changes or new product features should be applied . A typical change control board will also decide which errors to correct in which versions .CCB Is the owner's equity representative of the system integration project , The load ruling accepts those changes .CCB It is composed of many members involved in the project , It usually includes decision makers of users and implementers .CCB It's a decision-making body , It's not an operating agency , Usually CCB The job of the project is to determine whether the project can be changed by means of review , But don't propose a change plan . At least it will guarantee , Decision making decisions are collective wisdom .)

NO.8 test

1、 Compare Huawei's and Xiaomi's tests from the perspective of progress

According to millet UI Weekly release progress , An internal test on Thursday . According to Huawei's process, I can't set it out .

The puzzle is :

1、 Internal testing refers to self testing by developers , Or the tester's test ?

2、 If you mean developer self testing , So where do testers test ?

3、 If it's a tester testing , What about developer self testing ? Where is the point of development to test ?

Huawei background friends will certainly ask : How can testers complete the test in a day ?

Someone might say , Xiaomi's efficiency is high .

Let's take a look at Huawei's testing process , You know if you can compress it to one day to complete the relevant tests .

First of all, let's make a point , Huawei's software department , Include UI、 Or the development team of the website is also developed in small steps , After the product stabilizes , New requirements will be split into smaller versions , Conduct the shortest cycle of development testing . It is also possible that Huawei's demand for dismantling is weaker than that of Xiaomi , But let's just talk about the testing process .

Testing is an essential part of product development , Among Huawei's R & D personnel , Nearly a third of the people are testers .

Huawei's test system started earlier in China , It has probably gone through these stages :

1) Bronze Age : Manual workshop testing

1996 The R & D testing team set up a manual workshop for R & D process and testing

2) Iron Age :IPD and CMM Stage

1998 Love and love IBM cooperation , Introduction IPD technological process

1999 The introduction of CMM idea

produce IPD-CMMI technological process

2004 In IPD Development based on PTM technological process , Automated test scale development

2006~2007 About years ago PTM Towards perfection

notes : Each one in the picture above TR The meaning of dot is as follows :

HLD: Architecture Design ;

LLD: Detailed design documents ;

1. UT

The object of unit test is LLD A program unit or module defined in , It is also the largest testable unit in unit test case design . The test object may consist of one or more functions or classes , Test design is to design test cases for test objects .

UT Purpose , Is to check the module code through the function run for LLD Document compliance , Verify the input and output response of each function , Is it consistent with what it is pre-defined in the detailed design document . Function is the most basic unit of product development , The next unit of implementation is the module , From a testing point of view , hope UT After completion , Every function is solid and reliable , The next step is IT The test will focus on whether the coordination between functions can achieve the allocation requirements , You don't have to worry about the input and output response of the function itself .

Unit testing is more suitable for developers .

2.IT

Integration testing refers to the testing of several unit tested units assembled together , Test integration should be based on HLD, The main discovery interface 、 A mistake or imperfection in dependency . The object of integration test is the combination of several unit test objects , For at least two .

IT Purpose , It is the decomposition of modules according to the module design , Start with a validated function , Layer by layer integration , Get a runnable module .

IT It can be done by developers , It can also be done by testers . It's not hard to see. ,UT It's testing for every unit ,IT It's the interface between test units , You can put UT/IT Classified as “ Unit level ” test .

3.ST

CMM Defined system tests : System testing is the overall test of the software system developed by the software project team , Testing that runs a software system as a whole or implements a well-defined subset of software behavior . The main test method is black box test , That is, regardless of the internal implementation logic of the program , To verify whether the input and output information meets the requirements specified in the specification . so ST The test object is the specification , More precisely , It's a module requirements specification , So it's also known as MST. modular SRS The document gives the input and output requirements of the module .MST after , Each module is firmly available .

4.BBIT

BBIT Test the interface between modules , Verify whether the interface between modules can cooperate , Sometimes mixed up with joint debugging , In fact, the purpose is not the same .BBIT Purpose , It's the decomposition of a system according to its design , Start with a validated module , Layer by layer integration , Get a working system . And joint debugging generally involves software 、 Hardware or cooperation test between different products .MST and BBIT Can be attributed to “ Module level ” Test of , A verification module , An interface between verification modules .

above UT/IT/MST/BBIT It's usually done by developers , The system can basically run , Testers can develop SDV、SIT、SVT 了 .

5.SDV

SDV Although it belongs to the system test carried out by testers , But it's a little bit gray box test , because SDV Verify that the cooperation of each subsystem meets the design requirements (DR), The internal implementation is still concerned about , Verify whether the integration of multiple modules meets the design requirements .

6.SIT

SIT It is also to verify whether the design requirements are met , And SDV The difference is ,SIT Test the system as a black box , Don't care about the internal concrete implementation . Practical application ,SDV and SIT Although it belongs to the system level test , Often by different project groups ( Subsystem ) The testing staff of our company tested , They only focus on their own subsystems , So I still put SDV and SIT Classified as “ Subsystem level ” The test is better .

7.SVT

SVT It's acceptance testing , The test object is product package requirements OR. Package requirements give the scope of the product , Describe the system from the perspective of the possible application environment of the product ,SVT The purpose is to confirm ( Or acceptance ) The various application scenarios given by the product package requirements can meet .

Even web development projects , Outsourcing projects , Terminal project , Huawei's test will still go through the following test stages :

SIV:System Integration Verify System integration verification

SDV:System design Verify System design verification

SIT:System Integration Test System integration test

SVT:System Verification Test System validation test ( System simulation test )

After iteration , Before the official release , It will implement all the Story One more test , test The subject of the tester , Include features 、 Non functional , And give a test report . This activity is called SIT Test or release .

If Story test 、 iteration SDV The tests are automated , This test is mainly to execute automation use cases 、 As before There is not enough testing , Then add a test , And detailed performance testing . If use case automation is not high , This test will The swipe section is used for testing . The test report should be given after the test .

SIT The test point : After all iterations have been developed , Regression testing of the whole system is completed by testers in the iterative development team , achieve TR4A The quality standard of . The remaining problems should be satisfied TR5 Of DI( Defect density ) The goal is .

4) Era of group army :IPD-RD-I&V Stage

2008 Around the year, agile began to be promoted , The R & D organization has evolved into PDU The way

Introduce iterative development mode , formation IPD-RD-I&V technological process

System integration and verification process :IPD-RD-I&V(I&V:Integrationand Verification)

Project Management Forum

《 test plan 》 It needs to be reviewed after writing , There are project managers involved , Test manager and Systems Engineer , The test team leader needs to modify according to the review comments 《 test plan 》, And upload them to VSS On , Managed by the configuration administrator .

Project manager Alliance

Wait for the developer to put 《SRS》 Summarize and base line , The test team leader began to organize the test members to write 《 Test plan 》, The test plan is based on 《SRS》 Each demand point on the design, including a brief introduction to the demand point , Test ideas and detailed test methods of three parts of the program .《 Test plan 》 It also needs to be reviewed after writing , The reviewers include the project manager , Developer , Test Manager , Test team leader , Test members and system engineers , Return to the review results . The test team leader organizes the test members to modify the test plan , It's not until the review is passed that the next stage ―― Write test cases .

Test cases are based on 《 Test plan 》 To write the , adopt 《 Test plan 》 Stage , The tester has a detailed understanding of the requirements of the whole system . Only when we start to write use cases can we ensure that the use cases are executable and cover the requirements . Test cases need to include test items , Use case level , Preset conditions , Operation steps and expected results . The operation steps and expected results need to be detailed and clear . Test cases should cover test scenarios , And the test plan covers the test requirements , Only in this way can we ensure that the customer needs are not missed . Again , Test cases also need to be passed through developers , Testers , Review of system engineers , The test team leader also needs to organize testers to modify the test cases , Until the review passes .

At the stage of writing test cases , The developers basically complete the code , At the same time complete unit testing . After transferring to the test department, the system test can be carried out directly . The test department pre tests the test version just transferred , If the software is not implemented CheckList On the list 10%, Testing will return the version to . otherwise , The software is transferred to the testing department for system testing . according to 《 test plan 》 Schedule , The test team leader conducts multiple tests , After the completion of each test, the test team leader needs to write a test report , This includes the use case execution status , Defect distribution , The cause of the defect , Risks in testing, etc , At this point, the tester will modify and add test cases . After the development and modification bug And a new beta version , The test department started a second round of system testing , First, go back to the questionnaire , And continue with the test , Write the second test report , Go on like this , Until the end of system testing . During system testing , Testers also need to write an acceptance manual , Acceptance case and data test case, etc .

Revise the questionnaire , Until the specified defect density is met , Only through correlation TR spot .

If the defect rate found in acceptance is in SOW To the extent specified , Then the acceptance is successful . If the specified defect rate is exceeded , Need quality backtracking .

2、 Incredible millet 5%

Lei jun says :

Let's look at Huawei's hardware testing process , We'll know where the cost is .

First of all 、 The whole process of testing participation :

second 、 Multi level testing and experimentation

For circuit design , Will do unit testing 、 Whole machine test 、 Small batch trial production 、HALT test 、 Environmental tests 、EMC test 、 Heat test 、 After entering the production process, we will carry out HASS test . Special equipment will also carry out salt spray test 、 Vulcanization test . The structure of the whole machine will be carried out : Drop test 、 extrusion 、 Twist and so on .

HALT(Highly accelerated life test) High accelerated life test .HALT It's a process of finding defects , It is achieved by setting up progressively increasing environmental stresses , To accelerate the exposure of defects and weak points of test samples , And then the exposed defects and faults from the design 、 Analysis and improvement of technology and materials , So as to improve the reliability , The most important feature is to set the environmental stress higher than the design operating limit of the sample , Thus, the exposure time of failure is much shorter than that required under normal Reliability stress conditions .

Environmental test is to ensure that the product is within the specified life period , In the intended use , In all environments of transportation or storage , The activity of maintaining functional reliability . It is the exposure of a product to natural or artificial environmental conditions to withstand its effects , To evaluate the product in actual use , Performance under environmental conditions for transportation and storage , And analyze the influence degree of environmental factors and its action mechanism .

HASS Applied to the production stage of a product , To make sure that all are in HALT The improvement measures found in can be implemented .HASS It also ensures that no new defects will be introduced due to changes in production process and components .

Hardware engineers are most afraid of HALT test , Because it will go beyond the limits of the device . But why do you do this , It's actually finding the weakest point in the whole device , Then improve the weakest points . But because it is beyond the allowable working range of the device , There are a lot of anomalies , The reasons are complex . But according to the norms, it must be analyzed clearly , And give the optimization measures . This is a very brain burning opinion thing , A lot of the classic questions are HALT During the experiment .

Because I was born out of a test , If there is something wrong, please correct it by experts . Now Xiaomi is no longer in its former days , Thinking of Lei Jun's 5%, Just write down these .

disclaimer : Source network of this paper , The copyright belongs to the original author . If involves the work copyright question , Please contact me to delete .

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