This switched Hardware hundred thousand why
Once I said that at the beginning of hands before the draw schematics , need to do requirements analysis , thematic analysis and so on work. But before you actually start, there is an iterative process of iterative design. There are also some background research and development is not the boss of me to complain, hardware engineers to make structural design, structural engineers, hardware engineers say should give a rough demand, do not know who should move.
It must first of its profits is to say: Craftsman want to make his job well, be sure to make the tool sharp. Metaphor to do one thing, the preparatory work is very important. A phrase from the "Analects of Confucius Duke Ling of Wei": Zi Gong asked for Humanity. Confucius said: ".. We must first of its profits for the state also ranks are, what their doctor's Sage, Friends of Chevalier of the benevolent" This preparatory work, of course, not only refers to the prior tools, as well as hands-on planning, thinking, assessment, program design, architecture and design.
Hardware Engineer hands before drawing schematics, need to draw the stuff is a program block diagram of a circuit board to draw with "wretched" (Visio).
Of course, each engineer has their own preferences. Some people like to use Visio, some people like to use PPT, it does not matter. The key is a block diagram of this board is not a simple racking our brains out .
Its birth, is a circuit board design process. If this stage of racking our brains , back to the board will take the thigh , ultimately Paipaipigu leave.
So how can we complete the design process of a circuit board it? In addition to our experience, what we need to do it?
[Step one, establish an archive folder, a clear plan to archives]
Recommended self-built cloud SVN server, need to archive folder speaking, be required to set up a folder in accordance with the needs of the enterprise or the project. These natural that we complete a full product in product development, production and consider the needs of all dimensions, need to archive all the contents of the Program.
github or network folder is shared in fact be, but a little github fast enough to design productivity, network folder version management is not easy, when the server failure will affect the development of the whole team, not easy mobile office.
[Step two, the establishment of a tracking mechanism]
previous series, we specifically said that the issue tracker, we focused on the current project, you need to establish a system of regular meetings, depending on the quality of personnel and personnel situation requires targeted for regular meeting. May be daily morning meeting, weekly meetings can also be flexible to grasp the tracking frequency.
But we need to build for the project issue tracking table of the project, to facilitate all problems throughout the course of the project, the closed-loop tracking, issue tracking occurs to avoid missing.
Of course, we can also calculate a more complex form, before we make a form to complete each task can be calculated in advance, the number of days of delay, the assessment can be made as a KPI. (This approach does not advocate)
[Step three, the tracking needs]
Huawei, this part will be assigned by the decomposition of SE (system engineer, system engineer is not stupid engineer). Hardware engineers checked against the distribution according to the results of decomposition, and the board needs to create a trace table. After tracking form to be convened SE, the whole structure, product engineering processes (PCB Layout Engineer, Process Engineer), production, testing, software and other peripheral staff review archived.
Of course, we always expect the demand can not be modified after filing. But we will find in the design process will inevitably be modified. But we should ban after TR3 is modified, if the additions and changes in demand after TR3, all demand changes need to be tracked by CR (needs to change the flow of electrons).
From a hardware point of view of stability, in the latter part of the project, the greater the impact of the demand for change, bringing design changes, the greater the impact on quality. But with the agility of thinking, and customer demand may change in the course of a long cycle of hardware, a lot of scenes that we have to demand change.
| No. | Various stages of introduction | Remark |
|---|---|---|
| 1 | Charter | Main responsibilities : Marketing team and SE; main work : Charter need to answer these questions: Version of Top N demand and the main competing demands, the main target customers, complete package demand version of the milestone point in time, the time window applications, and in versions train in which the position of the |
| 2 | Charter-TR1 | Main responsibilities : SE team, and Marketing with the completion of refined demand clarification and revision; main work : design output requirements (including input and output parameters of each requirement, and low-fidelity output interface prototype) |
| 3 | CDCP | The main work : In recent years most of the projects are cut, the specific role is unknown |
| 4 | TR1-TR2 | Main responsibilities : SE team; the main work : the output is a design specification (interface design, interface high-fidelity prototype) |
| 5 | PDCP | Main responsibilities : development representative; the main work : The main work: code size, the key point in time and manpower requirements. Quality objectives, SOW (statement of work) |
| 6 | TR2-TR3 | Main responsibilities : development team; the main work : The main work: Requirements Specification (SRS); system test (STC), the outline design (HLD), integration test cases (ITC) |
Analysis and understanding of the needs are often not in one step, understanding of R & D personnel also may not be very accurate understanding of the scene scene. So after completion of requirements traceability, the need for chuanjiang needs two rounds, anti-Chuan Jiang. (Crosstalk refers to the needs of publishers and developers explain, after the anti-Crosstalk refers to developers understand the demand, the demand for the publisher to explain).
Anti construe demand, the designers SE, one by one to explain the role of the project manager and other hardware requirements, unified understanding. For the implementation of existing demand, to explain the program to be included. Crosstalk Crosstalk and be sure to let the anti-SE / software / testing field full participation, to solve all the issues raised in the loop before detailed design begins.
[Step 4] key device analysis
we developed a new project, inevitably we did not use the device used, or even the entire company have not used the device.
After we selected basic plan depending on design requirements, the need for application analysis, application analysis of new output devices, key components, and to convene the relevant personnel, managers, experienced engineers review and analysis.
Bug List program analysis and design considerations need to refer to the process and update the device. While collecting case, and gives solutions to address measures to advance the prevention of known issues.
Key device is not limited to the introduction of new devices, the device also includes complex devices, developers and project team experience are insufficient.
Analysis of the key devices, we need to datasheet of the device analysis, find and Demo board inspection of factory errata, looking for changes that have been commercialized or have completed a design, part of the circuit, need hands-circuit test, or do circuit simulation for verification.
[Step five, pre-layout and design]
us on demand, clear the necessary functionality, performance, and then clear the key components, which is above the board high-power devices, the new devices, complex devices have been finalized. So we can do a pre-layout, clear board size, roughly the idea of shape.
We To achieve an accurate pre-layout needs to output a pre-layout schematic diagram claim comprising at least main components, a power supply, the heat sensitive devices and connectors.
Prelayout board needs to signal flow , a device function , the power pin main distribution device , the basic power distribution and flow of the entire circuit board .
Then the relevant demands, to provide ID engineer, to envisage a basic ID, and then refined by the structural design of the structural engineer.
If the chassis is mature, then the process is relatively simple, e.g. ATCA, VPX such standard chassis. The possibility of some personal consumer electronics products of this process is repeated very large.
To avoid this process, hardware engineers completed the initial pre-layout, then it should put its own design demands , all the records in "structural elements drawing design Guide" , to provide structural and ID engineers.
[Step 6] Thermal Assessment
hardware engineers need to provide the board layout and components heat consumption (power consumption) table , each of the heat from the device parameters . Digital devices to be noted that as far as possible to provide accurate power consumption data , in particular, DDR / FPGA devices, etc. to be calculated based on usage scenarios. Power consumption of the device needs to provide accurate, avoid over-design, but also to avoid the risk of heat dissipation.
[Step 7] to assess import new devices
at Huawei, a new import devices is very complicated, we do not Huawei, select the new devices also need to be careful to select, and make the relevant assessments.
In fact, this should be a sourcing process: we not only consider the needs of new device features meets our needs, also need to consider: reliability, procurement, cost, welding technology, power, cooling, and other dimensions.
[Step eight, FMEA pin assignment analysis backplanes, board]
we need to standard backplane, circuit board pin distribution. If it is a new design backing plate, the backing plate need to consider the cost of the connector, the rate, number.
In the product design stage, FMEA to analyze for all inter-board signal / key components, ensuring trouble-free omissions. To analyze the impact of all faults, and fault management capabilities to achieve optimization. In this process, the presence of two criteria, that is, for a serious failure, requiring the maximum extent possible to avoid; for failures need to be addressed, requires the ability to monitor and navigate to the Field Replacement Unit (FRU, Field Replacement Unit).
[Step 9, normalized analysis]
Normalized As part of the DFx requires hardware special attention. Each product needs to sort out its own BOM normalized list of devices, commonly used device selection can only choose the normalized list. Normalized list for the enterprise or the department used the device or through the purchase of devices.
Minimize device types, device types reduce not only reduce management costs, but also reduces processing and purchasing costs.
[Step 10, the reusability of analysis]
All boards reusable analysis should be carried out, comprising three elements:
1. The existing circuit board reusable;
2. The circuit board desirable to reuse;
3. after the completion of the development of the single board can provide other items reuse circuit.
[Step 11, early BOM review]
1. After determining the program put the key components have been identified, the key components of views through the procurement feedback.
2. All non-conventional devices, non-mainstream device, the device must be individually and purchase confirmation, detailed risk assessment, risk devices to choose alternatives.
3. There are key components change during the design process, also need to be confirmed with the procurement staff.
After the above eleven steps
1. We selected key components, and the pre-layout, clear design structure, eliminating the risk of feasibility, procurement, reliability, heat dissipation area.
By tracking needs to ensure that all requirements can be implemented in the design, the final design of the product meets customer needs.
By normalization, reusability analysis, enhance the overall design efficiency, and enhance the design quality hidden.
By "issue tracking table" to establish "archive folder" to ensure the delivery of the project management.
After these preparations, we block diagram of the circuit design is reassuring circuit schematics and reliable.
