When it comes to hardware development in China, Huawei is undoubtedly the best company. Therefore, hardware entrepreneurs come out from Huawei. This article introduces the process of Huawei hardware development in great detail, which is worthy of reference by other hardware developers.
Many friends consulted some hardware problems and found that friends did not carefully look at the datasheet, and did not do a good circuit analysis. I will talk about how Huawei is doing hardware development and give some inspiration to friends who are doing hardware development. The wrong place is said, everyone criticizes and corrects.
In 2007, when I was working for 2 years, I went to a small company to go to the interview. At the time, I felt that I was doing very well. When I was interviewing, the other person also recognized me. But he said at the time: "I need to recruit one, I have to wait in a big company, it is best to know the hardware development process and specifications. Although you have a good answer, we need a rich experience, preferably in Huawei. of."
At that time, I was thinking that "Huawei's specifications and processes are the same," and I always wanted to see. Previous interviews with Huawei have not been very interesting. After that, I really want to have the opportunity to go to Huawei to see. 2008 arrived at Huawei.
I can think of Huawei's hardware development several different points, share with you, think about where to write, welcome everyone to criticize and correct.
1, documentation, review, design.
2. The composition of Huawei's hardware field:
3. Huawei's process
4. Normalization
5, thematic analysis
6, device selection
7, whiteboard explanation
8, the problem is solved
1, documentation, review, design.
When they first joined the company, three people made a circuit board. Although the circuit is more complicated, there is still some manpower surplus. So, I was arranged to write a PCI to UART logic.
I was a new employee at the time, and I was eager to show myself. Using the time of the weekend, it took an estimated one week to finish writing the code and start the simulation. I thought that my mentor and supervisor would praise it. The result was not. He said, "Why didn't you convene everyone to discuss? Then write the plan, review? Then write the code again?" I didn't understand it at the time, I felt that I was alone. What do you want to do in order to do this?
Rethinking now:
First, from the perspective of the supervisor, I don’t know the personal ability of the new employee. You can make it clear that he can do things clearly.
Second, from the company's perspective, there is a process to ensure the delivery of the project. Then it is no longer too dependent on someone's personal ability, and the departure of any one person will not affect the delivery of the project. This is also the most remarkable place for Huawei to dismantle complex projects so that no special cattle are needed to deliver the project. This is why the revenue of Huawei engineers is one-ninth of Cisco's.
Third, from the perspective of effect, after all, one's thoughts are limited. The process of documenting ideas is the process of sorting out ideas; the process of discussion is to collect processes that you did not think of. The formal review is the process of reaching an opinion. Discussing in advance, letting the relevant people participate in your design, is better than the end of your design, and being pointed out by a others to be a fatal problem.
It is because Huawei has broken up a job, so communication, documentation, review, and discussion have become very important.
The shortcomings of this working mode are also obvious, the communication cost is high, and the work efficiency is low.
2. The composition of Huawei's hardware field:
Inside Huawei, there are many people roles. The hardware is responsible for the product development phase, end-to-end.
As a single-board hardware engineer, you can get involved in the most fields, and at the same time, it is also the most miscellaneous job, the most contacts, and the most work.
Huawei's hardware structure
But also because someone is responsible for drawing PCB, EMC, power, logic, the field that the original hardware engineer should do. Then the hardware engineer is completely ruined and becomes a "connected line."
In fact, it is because everyone is a small field and no one is in charge. Therefore, the role of a good hardware manager is very important and is a key role in all fields and processes.
Just as there is a metaphor in Huawei's internal forum, hardware engineers are more like "Cache" in the processor, which is a transit point for all links.
The big company divides the division of labor so finely, and it is also to prevent a certain core technology that has mastered too many companies.
3. Huawei's process
In fact, Huawei's process, many people know that the IPD process is from IBM, and Huawei has also consulted Ericsson, Ericsson's hardware development, there is no process at all.
I personally understand that the IPD process has been modified in Huawei, combining the characteristics of the Chinese, and Huawei's corporate characteristics have been modified and optimized. If Huawei is rigidly applying IBM's process, it will certainly not be so successful.
So summarize the hardware development process of Huawei:
Demand Analysis→Overall Design→Special Analysis→Detailed Design→Logical Detailing→Schematic Diagram→PCB→Viewing→Adhesive Logic→Plating Board→Production Trial→Return Board Commissioning→Unit Testing→Professional Experiment→System Joint Tuning→Small Batch Trial Production → Hardware stability → maintenance.
The root of the process is that this link is done and then moves on to the next step. All the links are not much different from other companies, but they strictly grasp the assessment conditions for entering the next link. What makes hardware engineers most entangled is that "there is no node corresponding to the 'boarding'."
Huawei's system supporting the IPD process is PDM (aka crawling slow)
The Chinese name of PDM is Product Data Management. PDM is a technology used to manage all product-related information (including parts information, configuration, documentation, CAD files, structures, permissions information, etc.) and all product-related processes, including process definition and management.
All of Huawei's device data, product components, tools, documentation, schematics, PCBs, logic code, etc. are present on this system.
But the system is too complicated, in fact, it is more difficult to use, and it is easy to be confused with server archiving and SVN archiving.
Some friends expressed their feelings and said that he felt "fine management of the process, so that everyone is a screw"; some colleagues also said that "team development is invincible"; some friends said "information security." Hahaha.
I am not a Huawei employee now. It does not involve Huawei's documents. It is more personal insights. It does not reveal any secrets of Huawei. Even secrets are the contents of my mind. What's more, these contents are not confidential. I just want to help more friends working in the hardware position, I also want everyone to see some feedback on the public account, let's discuss.
4. Normalization
Device normalization
Hardware engineers can generally understand that on a board, choose the lower cost device as much as possible, choose a smaller variety of devices, facilitate centralized procurement, and also facilitate processing. But other companies may not have done so detailed and rigorous work on device normalization.
First, because Huawei's entire company uses a very wide variety of devices, if you reduce a device code, the benefits will be 100,000 yuan to several million, and other companies may not achieve this high return. So if you can reduce a code, you would rather choose a device that may cost more. However, this also needs to be compared with the annual device direct cost benefit * device shipment quantity, and the coding cost + processing cost difference. However, after the device is normalized, the price of the device can be re-talked to the price with the supplier. This benefit is iterative. Therefore, sometimes even if the cost is dominant, it will tend to the conclusion that the device is normalized. For example, a 5% precision resistor is gradually removed and normalized to 1%.
Second, the device is normalized and requires a special analysis. Because some engineers have not fully analyzed the circuit principle for normalization, the resulting normalization brings "problem introduction." So, at the time, my department had a form, the "device normalization analysis.xls" excel table, the record of each device, the original selection, the normalized selection, the reason for the change, and the reason analysis. First, let each of the normalized employees fully consider the analysis. Second, the problems are recorded and easy to review. Third, there is a problem, so that the board is good.
Single board normalization
In addition to device normalization, a higher level of normalization is the normalization of the board. (The concept of the board, I clarify a little, when I first arrived at Huawei, I also felt that the word is very strange. Because the communication equipment is the chassis, the backplane, the circuit board of each functional module, the circuit of each functional module. It is called "single board", hardware engineer, generally called "single board hardware")
The benefits of single board normalization are as follows: firstly, there are few types of circuits, and there are two advantages of less types of circuits: first, the production cost is reduced, second, the hardware maintenance cost is reduced, and third, the cost of software development and maintenance is reduced.
First, the prerequisite for board normalization is first processor normalization. In fact, some of Huawei's products are actually not good. X86, MIPS, ARM, and PPC all use it all the time. Therefore, a hardware platform needs to be equipped with various software personnel. The operating system is N sets, VxWorks and Linux. Various BIOS packages.
Second, the normalization of the board, we must pay attention to the derivative of the product. The functions implemented by the boards on the first version of the chassis, if the subsequent products can be used, should be used directly, no need to develop. If you don't pay attention to this, the first version of the board, when you go to the second version, find that you can't borrow each other. In turn, modify the first version of the board to accommodate the new version. Sometimes the problem is even worse, it is completely incompatible and I have to redevelop. The planning of the board is very important.
Third, when the board is normalized, although the circuit is partially compatible, the structural parts are not compatible. For the configuration of marketers, there are still two configurations. The same is a failure.
Platform normalization
Then, if the architecture of different hardware platforms is found to be similar, the functions are similar. Then the chassis can also be normalized. Only need to make different circuit function modules, you can achieve different functional requirements.
But different hardware forms have the meaning of his existence. If forced to be normalized, the market may not accept such things. For example, using an operator's platform to group products for an enterprise application or home application may not be successful.
Network architecture normalization
This statement is my own thinking. As early as 2008, Huawei was discussing the "cloud management strategy", which was not very understandable at the time. When we merged with the "server" department of an operator platform department, it seems to understand something.
When the X86 processor is powerful enough, all operations, whether cost-effective or not, are sent to the cloud for processing, so all intermediate storage and calculations are not important. Then the structure of the entire network is terminal + pipeline + cloud storage and cloud computing
Network architecture normalization
Since the computing and storage devices are the same, the computing and storage devices do not need to be so diverse. Network storage devices and servers are especially important at this time.
This is also an important reason why Huawei has established an IT product line and made key strategic investments.
So now there are not so many network nodes and network platforms, only powerful processing and storage capabilities and wide channels, and diverse terminals.
Fifth, "thematic analysis" is the core work of designing hardware, not drawing schematics.
Because today is the weekend, write something easier.
Let me tell a story first, legend, ha, everyone laughs.
In the early days, the submarines that I had researched in China were all sea blue, and the color of the warship was “blue-grayâ€. Later, my great navy went to visit the military exercises of the former Soviet Union and found that the Russian submarines were not blue and black. So I came back to discuss, the Russian submarine is black. Guess: It must be black that is not easy to be found in the night, so it is painted black. So the national paint movement. Later, I learned that the black of the Russians was not paint, black rubber, and anechoic tiles. So we also put rubber, but after we put on the rubber, the submarine can't run because our submarine is not as powerful as others. (The above story is purely fictitious. If there is any similarity, please change the time to the Qing Dynasty.)
Why are you here to tell the story of the failure of the gourd painting? I feel that many hardware engineers have a misunderstanding. I feel that my core competitiveness lies in the use of several software (cadence, Protel), drawing schematics, and drawing PCB. My early work was like this. The biggest skill is to take the gourd painting, copy the Demo board, copy the mature circuit. If you encounter a new circuit design, you should first draw the circuit according to the reference circuit and then debug. Try it, get into the problem, and solve the problem.
Hardware engineer workflow
So my current concept is that the most valuable part of hardware engineers is to understand the hardware principle, understand the circuit analysis, the modulus of electricity, the electromagnetic field theory, rather than using drawing software.
So how does Huawei do circuit design? Why is there a topical analysis? Why do special analysis when designing a circuit?
First, routine, each circuit will generally do several mandatory topics: power supply, clock, small system; how to use each pin, how to connect, whether the level of the docked pin meets the requirements, Need to be documented and analyzed clearly. When choosing a new device, the workload of the corresponding hardware engineer is still relatively large. But if it is another company, it will be done directly according to the recommended circuit design. Power supply topic, need to analyze power demand, voltage range of each power supply, current demand, dynamic response, power-on timing; clock topic, level standard for each clock input, frequency, jitter and other parameters, clock timing, and Various clock solutions are optimized;
Second, when the circuit design process, encountered some new problems, the problems that have not been touched by the team before, or the content that is considered to be the key and difficult, will be special analysis of the problem points: for example, some of the things we have done Dual BIOS boot, camera infrared LED driver, master-slave switch, and so on, will analyze a problem point, and then do the drawing master.
Third, then when developing hardware, Demo is only for reference. Each basis is from datasheet. In addition to looking at the data sheet of the chip, you should also carefully check the errata of the data sheet to check the difference between datasheet and Demo. One thing, if the device has a checklist, you have to check the checklist. When I was developing AMD, the datasheet, Demo, and checklist were not in the same situation. Also appeared, a problem that is more difficult to reproduce. Later, I checked Errata and found that the manufacturer's chip was upgraded, the bug was fixed, and we are still purchasing the old version of the chip.
Fourth, because the project itself has delivery time requirements, it is impossible to make every problem point deep and thorough in a limited time. Then the question is coming:
How did it do it? First of all, each project has a "problem tracking table", and the hardware team is very mixed because of the things, so the table is very good, otherwise it is normal to lose the East Lacy. I used this watch to decorate my home. The principle of this table is very simple, that is, the record, the content of the problem, the responsible person, the completion status, and the completion time. But as long as you stick to it, you will find that your problems will not be tracked, things will be more organized, and there will be a sense of accomplishment. After using this table, after discovering the problem, record it first. Even if it is not solved now, it will identify whether he wants to solve it or not. Second, the issues are prioritized. Any project is advancing with risk. Identify high-risk issues, prioritize high-risk issues, and continue with low-risk issues. This is also one reason why Huawei's circuit design uses more "0 ohm" resistors. After identifying the risks, but the analysis is not clear, or it is too late to analyze, we have to do compatible design. I have to be sighed here. In your design process, you are sloppy, and there is no clear problem, and you will definitely be exposed.
Therefore, in the "Chrysanthemum Factory" as a hardware engineer, "thematic analysis" is the core work of designing hardware, rather than drawing schematics.
Through this method, the circuit analysis is performed in 1~2 months, and the schematic is drawn in 1~2 weeks, replacing, drawing, debugging, revising, re-commissioning, in the form of revision.
How fast and cheap, it is impossible to achieve at the same time, then hardware engineers have the responsibility to make good compromises and trade-offs.
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