Hello everyone!

大家好！

In this article, we will consider common errors in the design of electronic devices and how to solve them. We will see how to calculate the cost of rolling back a batch of devices, get familiar with the main prototyping cycle.

在本文中，我们将考虑电子设备设计中的常见错误以及如何解决它们。 我们将了解如何计算回滚一批设备的成本，并熟悉主要的原型设计周期。

介绍 (Introduction)

You have probably heard that various manufacturers recall batches of electronic devices from time to time. Smartphones hanging up, cameras turning off suddenly, electronic cigarettes exploding — these are the results of an incorrect approach to prototyping devices and savings on-device testing.

您可能听说过，各个制造商不时召回一批电子设备。 智能手机挂断电话，相机突然关闭，电子烟爆炸-这些是对原型设备使用错误方法并节省了设备内测试的结果。

For users, such cases look like routine and can only undermine their trust in the device manufacturer. For a company that has released insufficiently tested devices in a series, defects can lead to recalling of the entire party of devices, paying compensations, and even bankruptcy.

对于用户而言，这种情况看起来很常规，只会破坏他们对设备制造商的信任。 对于一家发布了一系列未经过充分测试的设备的公司，缺陷可能导致召回整个设备方，支付赔偿金甚至破产。

真实案例 (Real-world cases)

Nowadays almost all portable or stationary devices have intelligent control. They use the computing capabilities of microcontrollers, microprocessors and processors for their work. This means that to change complex electronic logic, one will need to make changes in the software. This approach simplifies debugging, development, and error fixes, also reducing the cost of devices. Besides, manufacturers try to protect themselves by preferring software solution to hardware solutions for flexibility of the manufacturing process. As technologies develop, technical requirements for devices become more and more complex. Due to their complexity, modern devices should be properly designed and tested.

如今，几乎所有便携式或固定式设备都具有智能控制。 他们使用微控制器，微处理器和处理器的计算功能来进行工作。 这意味着要更改复杂的电子逻辑，就需要对软件进行更改。 这种方法简化了调试，开发和错误修复，还降低了设备成本。 此外，制造商试图通过选择软件解决方案而不是硬件解决方案来保护自己，以提高制造过程的灵活性。 随着技术的发展，对设备的技术要求变得越来越复杂。 由于其复杂性，应适当设计和测试现代设备。

Software errors are resolved by updating the device software, normally it doesn’t cause serious damage. Below you can find some examples of errors made by well-known companies:

通过更新设备软件可以解决软件错误，通常不会造成严重损坏。 您可以在下面找到一些知名公司所犯错误的示例：

• 2019 — a login error on a Samsung smart watch:
  2019 —三星智能手表上的登录错误：

• 2018 — an error causing the Apple iPhone restart when receiving messages with certain characters:
  2018年—当收到带有某些字符的消息时，导致Apple iPhone重新启动的错误：

• 2016 — a vulnerability in Android enabling attackers to access a number o smartphone models:
  2016年— Android中的一个漏洞，攻击者可以通过该漏洞访问多种智能手机型号：

• 2016 — an issue with the shutter being stuck in Nikon D750 cameras:
  2016年—尼康D750相机快门卡住的问题：

Errors in the software are common for any device manufacturer. They only indicate that the device circuit was properly designed so the device didn’t stop working, and the error resulted in zero hardware damage.

该软件中的错误对于任何设备制造商都是常见的。 它们仅表明设备电路的设计正确，因此设备不会停止工作，并且该错误导致零硬件损坏。

The errors in circuitry, layout of electronic components or mechanical parts, insufficient protection of the device from external influence lead to more serious consequences. Unlike software issues, they cannot be resolved remotely and result in higher costs as the manufacturer needs to pay for repair or even release another series of devices. Moreover, hardware errors often mean that the device won’t work properly.

电路错误，电子组件或机械零件的布局错误，设备不受外部影响的保护不足会导致更严重的后果。 与软件问题不同，它们无法远程解决，并且会导致更高的成本，因为制造商需要支付维修费用，甚至需要发布另一系列的设备。 此外，硬件错误通常意味着设备无法正常工作。

However, errors in the firmware of the devices (especially those performing simple tasks without the possibility of remote firmware upgrade) should not be treated irresponsibly either. Even if such errors do not make their manufacturer rework the circuitry, they can still lead to reflashing. When designing devices on simple microcontrollers with peripherals used for outer word communication, it is possible to add the function of remote firmware updates and protect yourself from device recalls. We will cover remote firmware upgrades in more detail in one of our upcoming publications.

但是，也不应该不负责任地对待设备固件中的错误(尤其是那些执行简单任务而无法进行远程固件升级的错误)。 即使此类错误不会使他们的制造商对电路进行重新加工，也可能导致重新闪烁。 在具有外围设备用于外部字通信的简单微控制器上设计设备时，可以添加远程固件更新功能并保护自己免受设备召回。 我们将在我们即将发布的出版物中详细介绍远程固件升级。

Here are some examples of hardware issues:

以下是一些硬件问题的示例：

• 2017 — Spectre, Meltdown — major hardware vulnerabilities at the core level of most Intel, AMD, ARM processors were detected. The command execution optimization mechanism could be used to access the arbitrary memory allocated for specific applications:
  2017年— Spectre，Meltdown —在大多数Intel，AMD，ARM处理器的核心级别检测到主要硬件漏洞。 命令执行优化机制可用于访问为特定应用程序分配的任意内存：

• 2016 — The discovery of a known problem with Samsung Galaxy Note 7 batteries causing smartphones to burn. Due to possible fires, some countries banned this model from air transportation:
  2016年—发现三星Galaxy Note 7电池已知问题，导致智能手机燃烧。 由于可能发生的火灾，一些国家禁止将此模型用于航空运输：

• 2013 — nowadays — numerous incidents involving the ignition of electronic cigarette batteries resulting in severe burns and injuries to users (warning! explicit content):
  2013年—时至今日—涉及电子烟电池着火的众多事件导致严重的灼伤和使用者伤害(警告！明确内容)：

These examples show that hardware errors in devices can be fatal to the device itself or to the manufacturer. This is why hardware development and testing must be more delicate.

这些示例表明，设备中的硬件错误可能对设备本身或制造商致命。 这就是为什么硬件开发和测试必须更加精细的原因。

设备中破坏性设计错误的简单示例 (A simple example of a disruptive design error in a device)

The consequences of hardware errors are clear, but why they occur? What is the reason behind them?

硬件错误的后果很明显，但是为什么会发生呢？ 他们背后的原因是什么？

Errors in the circuitry and mechanics of the device often occur due to the lack of load, crash tests, tests in an aggressive environment. The approach to developing hardware may be incorrect, too.

设备的电路和机械故障通常是由于缺乏负载，崩溃测试，在恶劣环境下进行测试而引起的。 开发硬件的方法也可能不正确。

Let’s say we designed a simple device — a component of the meteorological data collection system.

假设我们设计了一个简单的设备-气象数据收集系统的组成部分。

The device is installed on a hill (a lamppost, a tree trunk, a roof of some building).

该设备安装在小山上(路灯柱，树干，某些建筑物的屋顶)。

The device consists of the following parts:

该设备包括以下部分：

• a series of sensors;
  一系列传感器；
• a microcontroller unit;
  微控制器单元；

• a ZigBee transmitter;

  ZigBee发送器；

• a LiFePO4 battery with 2000mАh capacity;

  容量为2000mАh的LiFePO4电池；

• a DC/DC converter;
  DC / DC转换器；
• a charge/discharge controller;
  充电/放电控制器；
• a solar panel for autonomous working.
  用于自主工作的太阳能电池板。

The device is sealed in the IP67 housing (description: https://en.wikipedia.org/wiki/IP_Code).

该设备被密封在IP67外壳中(描述： https : //en.wikipedia.org/wiki/IP_Code )。

The block diagram of the device is as follows:

该设备的框图如下：

Let’s suppose that during the development phase, some tests were carried out to check:

假设在开发阶段，进行了一些测试来检查：

• Stand-alone operation using solar battery charging;
  使用太阳能电池充电的独立运行；
• Transmitting of actual sensor data at the required distance;
  在要求的距离处传输实际传感器数据；
• Current consumption of the device within the permitted limits;
  设备的电流消耗在允许的范围内；
• Hull tightness.
  船体密封性。

It looks like the device passed all the necessary tests, and it is possible to start serial production.

看起来该设备已通过所有必要的测试，并且可以开始批量生产。

Next, the following scenario is possible:

接下来，可能出现以下情况：

1. The device documentation for mass production is written.
   编写了用于大规模生产的设备文档。
2. A trial batch of 100 products is produced.
   试生产了100种产品。
3. The product is launched officially.
   该产品正式发布。
4. After a long and successful use during several months, the company produces a larger batch of several thousand units.
   经过几个月的长期成功使用，该公司生产了数千个较大的批次。
5. The ambient temperature gets higher as summer comes.
   夏天来临时，环境温度会升高。
6. Due to high tightness of the device and the lack of active cooling, the devices gradually heat up to the temperatures when their batteries become unusable.
   由于设备的高度密封性和缺乏主动冷却功能，因此当设备无法使用电池时，设备会逐渐加热到一定温度。
7. The battery capacity drops rapidly, making it harder to keep the supply voltage at the necessary level.
   电池容量Swift下降，因此很难将电源电压保持在必要的水平。
8. The DC/DC converter starts to operate at its power limit and lose conversion efficiency over time, dissipating more and more power.
   DC / DC转换器开始在其功率极限下运行，并随着时间的流逝而失去转换效率，从而消耗越来越多的功率。
9. The increased temperature of the device’s active elements causes a fire.
   设备有源元件的温度升高会引起火灾。

In this scenario, at best the devices will simply fail, at worst they will cause a fire.

在这种情况下，充其量设备只会发生故障，最坏的情况是会引起火灾。

In this example, the error is made at the initial stages of the construction of circuitry, as the device should have been load tested in aggressive conditions. To prevent the error in the remaining devices, it is necessary to completely change the approach to power supply and sealing.

在该示例中，由于该设备应该已经在恶劣条件下进行了负载测试，因此在电路构造的初始阶段就产生了错误。 为了防止其余设备出现错误，有必要完全改变电源和密封的方法。

This means that producing hotfixes for devices with problems in circuitry and sealing mechanics is simply pointless. It is much cheaper and faster to reissue the entire batch of devices.

这意味着为电路和密封机制有问题的设备提供修补程序是毫无意义的。 重新发行整批设备要便宜得多且速度更快。

硬件项目中的简单错误的价格计算 (Price calculation of a simple error in a hardware project)

If the errors from our example are detected in a real hardware project, the manufacturer will suffer colossal losses, and their reputation will also be affected, which may lead to bankruptcy.

如果在真实的硬件项目中检测到我们示例中的错误，制造商将蒙受巨大损失，其声誉也将受到影响，这可能导致破产。

If that hardware company from our example decides to re-design and reissue their simple devices, it will need to spend huge amounts of money on the redevelopment of problem parts and additional testing.

如果我们示例中的硬件公司决定重新设计并重新发行他们的简单设备，则它将需要花费大量资金来重新开发问题零件和进行其他测试。

Let’s make a simple calculation on how much it will have to spend on re-issuing the series of devices:

让我们简单地计算一下重新发行一系列设备需要花费多少：

Cost of parts: the price of parts for one device from the example ranges between $70 and $90.

零件成本：示例中一台设备的零件价格在70到90美元之间。

Development: fixing power supply and sealing problems plus preliminary test will take an Embedded Systems Engineer about 15 hours.

开发：修复电源和密封问题以及初步测试将需要嵌入式系统工程师大约15个小时。

Simulation, testing under aggressive environment: simulation of the device’s behavior in real-world, calculation of power consumption and dissipation, and tests in aggressive conditions can take up to 50 hours.

仿真，在恶劣环境下进行测试：在现实世界中模拟设备的行为，计算功耗和功耗以及在恶劣条件下进行测试可能需要长达50个小时。

The average cost of the Embedded Systems Engineer work is 30$/h.

嵌入式系统工程师的平均工作成本为30 $ / h 。

Thus, to correct the error from our example, the company will need about $ 2,000, and reissuing of the trial 100-device batch will cost it about $ 8,000.

因此，要纠正我们示例中的错误，该公司将需要大约2,000美元，而重新发行100个设备的试用批次将花费大约8,000美元。

The cost of lost time and customer confidence should also be added to the resulting amount. If the worst-case scenario unfolds, the damage compensations paid to the users will increase it even more.

损失的时间成本和客户信心也应添加到最终金额中。 如果最坏的情况发生了，支付给用户的损害赔偿将进一步增加。

How to avoid such mistakes? Which tests should be given more attention? What are the main design problems when it comes to hardware? That’s what we’ll talk about later.

如何避免这种错误？ 哪些测试应给予更多注意？ 硬件的主要设计问题是什么？ 这就是我们稍后讨论的内容。

原型设备开发的分步计划 (Step-by-step planning for prototype device development)

To issue a test batch of devices successfully, you need to have a fully tested prototype device and complete technical documentation describing the production technology.

要成功发布一批测试设备，您需要拥有经过全面测试的原型设备以及描述生产技术的完整技术文档。

The keyword here is “prototype” — a device that fully implements the required functionality and is ready for modification and optimization for the consequent serial production. More information about prototyping can be found here:

此处的关键字是“原型”(prototype)，该设备完全实现了所需的功能，并且可以为后续的批量生产进行修改和优化。 有关原型的更多信息，请参见：

When you discuss the statement of work and possible deadlines with the customer, it is vital to take into account the following facts:

当您与客户讨论工作说明和可能的截止日期时，考虑以下事实至关重要：

• If all your hardware modules are stable as separate parts, it does not guarantee that they will work together in any way.
  如果您的所有硬件模块都可以作为单独的部分稳定运行，则不能保证它们可以以任何方式协同工作。
• Successful prototyping does not mean that a product can be launched into a series — it is just one of the achievements on the way to mass production.
  成功的原型制作并不意味着可以将产品发布为一系列产品，这只是大规模生产中的成就之一。
• Each significant correction of the circuitry or mechanics requires the production of a new prototype. It also means another series of tests (no matter how long it takes, otherwise the production of prototypes does not make sense at all).
  对电路或机械原理的每次重大修改都需要生产一个新的原型。 这也意味着要进行另一系列的测试(无论需要多长时间，否则原型的生产根本就没有意义)。
• You need to allocate some extra time for prototyping as production depends on many off-project factors.
  由于生产取决于许多项目外因素，因此需要为原型分配一些额外的时间。
• While simulation and testing on debug stands to speed up the development at early design stages, they only add errors to the prototype at late stages.
  尽管在调试时进行仿真和测试可以加快早期设计阶段的开发速度，但它们只会在后期阶段为原型增加错误。
• One should avoid producing a large series of devices once the production technology is ready. It’s better to go with a small batch of devices to collect feedback and conduct tests in an aggressive environment.
  一旦准备好生产技术，就应该避免生产大量的设备。 最好与一小批设备一起在积极的环境中收集反馈并进行测试。
• At the design stage, it is necessary to allocate additional budget for purchasing the device analogues. You will also need to allocate time for initial research and reverse-engineering once you purchased them.
  在设计阶段，有必要分配额外的预算来购买设备类似物。 购买它们之后，您还需要分配时间进行初步研究和反向工程。
• All measurements of the device characteristics must be carried out with the “max” mode turned on.
  器件特性的所有测量都必须在“最大”模式打开的情况下进行。
• Load tests and tests under aggressive conditions should be performed for long periods of time in a prepared environment.
  负载测试和剧烈条件下的测试应在准备好的环境中长时间进行。

Let’s consider the approximate plan of development of a device prototype and preparation for batch production:

让我们考虑一下设备原型开发和批量生产准备工作的大概计划：

1. Device ideation.

   设备构想。

   Each device is here to solve some problem, and the optimal way to do it will not always coincide with the customer’s vision. It is necessary to review the idea and make proposals of your own.

   每种设备都可以解决某些问题，而最佳解决方案并不总是与客户的愿景相吻合。 有必要回顾一下想法并提出自己的建议。

2. Specification.

   规范。

   A detailed initial specification will help to stay focused on your actual goals while development and diminish conflicts.

   详细的初始规格将有助于在开发和减少冲突的同时专注于您的实际目标。

3. Roadmap for a prototype device. To allocate enough time, it is necessary to split the development of the device into several stages, taking into account the delays due to issues with component supplies.

   原型设备的路线图。 为了分配足够的时间，有必要将器件的开发分为几个阶段，同时要考虑到由于组件电源问题而引起的延迟。

4. Search for ready-made implementations.The development of a new device often implies that such a device is not yet available on the market, or its characteristics exceed those of its analogues. That’s why one shouldn’t focus on ready-made implementations and general-purpose components. The use of such components (ready-made peripheral modules, development boards) will allow speeding up at the early stages of the device development but will result in restrictions while prototyping and introducing changes.

   搜索现成的实现。 新设备的开发通常意味着该设备在市场上尚不可用，或者其特性超过其类似产品的特性。 这就是为什么不应该关注现成的实现和通用组件的原因。 使用此类组件(现成的外围模块，开发板)将允许在设备开发的早期阶段加快速度，但在原型设计和引入更改时会受到限制。

5. Device components search.

   设备组件搜索 。

   When choosing a component base of the device one should not put costs first. The cost of circuits, microcontrollers, boards is incomparable to the cost of potential instability (you may actually spend more on making cheap components work). It’s best to order parts from reputable manufacturers, for example,

   选择设备的组件库时，不应首先考虑成本。 电路，微控制器，电路板的成本无法与潜在的不稳定成本相提并论(实际上，您可能会花更多的钱使廉价的组件正常工作)。 最好从信誉良好的制造商那里订购零件，例如，

   Microsemi, STMicroelectronics, ON Semiconductor, Honeywell, Panasonic, Vishay, Texas Instruments, Analog Devices. When selecting components, you should examine their documentation in detail. If you don’t do this, you may find out that the purchased components do not fit the stated requirements.

   Microsemi ， 意法半导体 ， 安森美半导体 ， 霍尼韦尔 ， 松下 ， Vishay ， 德州仪器 ， 模拟设备 。 选择组件时，应详细检查其文档。 如果不这样做，您可能会发现所购买的组件不符合所述要求。

   This approach is relevant for special-purpose solutions where the device is supposed to perform only the functions required, no more than that. When using general-purpose modules, you have to save money as modular solutions are expensive. This affects the quality of components. Functionality can also be cut down. Such modules set limits on how they can be used. The high cost of development on ready modules should motivate you to use discrete components.

   此方法与专用解决方案有关，在该专用解决方案中，设备仅应执行所需的功能，而不能执行更多功能。 使用通用模块时，您必须省钱，因为模块化解决方案非常昂贵。 这会影响组件的质量。 功能也可以减少。 这样的模块限制了它们的使用方式。 准备好的模块的高昂开发成本应促使您使用分立组件。

6. Schematic development.To develop the schematic part of your device, you need to understand how each of your discrete components works. You will need to have a good documentation for all your components. Splitting all modules to simple parts will also help to avoid the “black box” effect. If your schematic is clear, it will enable you to avoid pitfalls at the consequent stages.

   原理图开发。 要开发设备的原理图部分，您需要了解每个分立组件的工作方式。 您将需要所有组件的良好文档。 将所有模块拆分为简单部分也将有助于避免“黑匣子”效应。 如果您的原理图清晰明了，它将使您避免在随后的阶段陷入陷阱。

7. Schematic simulation.

   原理图仿真。

   The simulation of the schematic part is very helpful at the early stages of design when it is necessary to check the low-level interaction of components. At the subsequent design stages, it becomes very difficult to simulate as the preparation of the simulator takes a longer time. The results may differ from the real behavior of devices due to many external factors that are hard to reproduce. This is due to the complexity of the circuitry and a large number of components. Also, a detailed simulation of large circuits in real-time requires huge computing power, which is not always available.

   原理图部分的仿真在设计的早期阶段非常有帮助，当需要检查组件的低级交互时。 在后续的设计阶段，由于准备模拟器所需的时间较长，因此很难进行模拟。 由于许多难以复制的外部因素，结果可能与设备的实际行为有所不同。 这是由于电路的复杂性和大量的组件。 而且，实时地对大型电路进行详细的仿真需要巨大的计算能力，而这种能力并非总是可用。

8. Tracing board, trace verification.

   跟踪板，跟踪验证。

   Numerous CAD (Computer-Aided Design Systems) like

   众多的CAD(计算机辅助设计系统)，例如

   Altium Design, KiCAD, EAGLE CAD, EasyEda can assist you with tracing and trace checking.

   Altium Design ， KiCAD ， EAGLE CAD ， EasyEda可以帮助您进行跟踪和跟踪检查。

   When developing a trace, it is necessary to make calculations for the length and width of conductors (based on the frequency of the transmitted signal, the value of passing currents), calculations for the location of elements, calculations of power dispersion of active elements.

   绘制走线时，必须计算导体的长度和宽度(基于传输信号的频率，通过电流的值)，计算元件的位置，计算有源元件的功率色散。

9. Order boards for a test batch.For rapid hardware testing and development acceleration at early stages, it is possible to produce prototype boards at home. At the subsequent stages of development, it is best to outsource board production (JLCPCB, PCBWAY are the examples of services for professional and low-cost board production).

   订购测试批次的板。 为了在早期阶段快速进行硬件测试和加快开发速度，可以在家中生产原型板。 在后续的开发阶段，最好将板生产外包(JLCPCB，PCBWAY是专业和低成本板生产服务的示例)。

10. Prototype assembly without firmware.

    不带固件的原型组装 。

    For the manufacturing of the first prototype, it is better to order or produce a small batch of boards (5–10 pcs.). You should also have to prepare an extensive element base for component replacement.

    为了制造第一个原型，最好订购或生产一小批板(5-10个)。 您还应该准备一个广泛的元素库，以更换组件。

11. Schematic testing.Device circuitry tests are performed as new parts are added to the board. Below are a few examples:

    原理图测试。 新电路板添加到板上时，将执行设备电路测试。 以下是一些示例：

    1. Installation of the feed elements.

    1.安装进纸元件。

    2. Checking connections.

    2.检查连接。

    3. Starting the supply part, collecting output characteristics in idle and limit modes.

    3.启动电源部分，在空闲和极限模式下收集输出特性。

    4. The assembly of the next part if the requirements of the first part are met.

    4.如果满足第一部分的要求，则组装下一部分。

    5. In the case of failure, discover the error and return to the item

    5.发生故障时，发现错误并返回到项目

    6. of the main list. (yes, it’s a lot of time between the start of development and the first tests, but it’s the only way to make progress — more changes mean more prototypes).

    6.主列表。 (是的，从开始开发到进行首次测试之间要花费很多时间，但这是取得进展的唯一方法-更多的变更意味着更多的原型)。

    Board manufacturers provide an option to automatically test all tracks and conductors according to the GERBER file. This service is inexpensive and saves you time and money at the subsequent stages.

    电路板制造商提供了一种根据GERBER文件自动测试所有轨道和导体的选项。 该服务价格便宜，可在后续阶段为您节省时间和金钱。

12. Firmware development for tests of interaction with the periphery.

    用于与外围设备交互测试的固件开发 。

    At this stage it is necessary to write the firmware that only correctly interacts with the periphery (not the one that makes the device perform its function). It’s important to include the main computational algorithms into the test firmware though.

    在这一阶段，有必要编写仅与外围设备正确交互的固件(而不是使设备执行其功能的固件)。 不过，将主要的计算算法包括在测试固件中非常重要。

13. Firmware testing. Testing of computing algorithms of the firmware can be performed locally, interaction with the periphery can be tested using a simulator. An example of testing for AVR microcontrollers is described in my previous article:

    固件测试。 固件计算算法的测试可以在本地执行，与外围设备的交互可以使用模拟器进行测试。 我以前的文章中介绍了AVR微控制器测试的示例：

Then you need to perform firmware testing using the debugger.

然后，您需要使用调试器执行固件测试。

14. The development of firmware that implements the device’s functionality.Firmware implementation based on the previously tested modules for interaction with periphery, computational algorithms, firmware optimization. Modular tests, tests on simulator, tests on hardware should also be performed. You can safely apply TDD at this stage.

14. 开发实现设备功能的固件。 基于先前测试的模块的固件实施，用于与外围设备交互，计算算法和固件优化。 还应该执行模块化测试，模拟器测试，硬件测试。 您可以在此阶段安全地应用TDD。

15. What if the schematic flaws are found out at this stage?If significant drawbacks of the circuitry (unstable behavior of the periphery, lack of computing power) are detected at this stage, return to item 5 (this means the inevitable loss of time and money).

15. 如果在此阶段发现了原理图缺陷，该怎么办？ 如果在此阶段发现电路的重大缺陷(外围设备的不稳定行为，缺乏计算能力)，请返回项目5 (这意味着不可避免的时间和金钱损失)。

16. Load tests, tests under aggressive conditions.Tests under aggressive conditions are best when conducted in a specially prepared environment that simulates external influences. You are supposed to have a dozen of prototypes with stable firmware to be crashed by maximum operating modes. Сollecting and checking the necessary characteristics of the device also takes place at this stage. If the tests fail, detect the issues and resolve them, return to item 5.

16. 负载测试，在苛刻条件下进行的测试。 在特别准备的模拟外部影响的环境中进行测试时，最好在剧烈条件下进行测试。 您应该拥有许多具有稳定固件的原型，这些原型会因最大工作模式而崩溃。 在此阶段，还需要检查并检查设备的必要特性。 如果测试失败，请检测问题并解决，返回项目5。

17. Preparation of design documentation for launching a product test series.You will need to prepare the documentation for your project as well as the production files. Then you are supposed to search for manufacturers, place orders for the production of boards, enclosures, mechanics. When the necessary equipment is installed locally, it is necessary to prepare the plan of technology for a batch production and hire the personnel (the given theme deserves a separate article, and we will cover it in one of our upcoming publications).

17. 准备用于启动产品测试系列的设计文档。 您将需要准备项目的文档以及生产文件。 然后，您应该搜索制造商，下订单以生产电路板，机柜和机械。 当必要的设备在本地安装后，有必要准备批量生产的技术计划并雇用人员(给定的主题应另作文章，我们将在以后的出版物中对此进行介绍)。

18. Certification (if applicable).If necessary, you need to get your device certified for daily use. Here are a few steps to be taken: — Contact a certification center. — Provide the officials with your technical documentation. — Send a small batch (up to 10 pcs.) of devices to the certification center for testing.

18. 认证(如果适用)。 如有必要，您需要对设备进行日常使用认证。 请执行以下几个步骤：—与认证中心联系。 —向官员提供您的技术文档。 —将一小批(最多10个)设备发送到认证中心进行测试。

19. Launch of a test batch not exceeding 100 pcs.Deliver your product and collect the first portion of user feedback paying special attention to product support. In the case of circuitry issues detection, search for methods to solve them, go to item 7. If software bugs are found, search for methods to fix them, and go to item 12. In case of successful use for a long period of time, launch a larger batch of devices.

19. 推出不超过100个的测试批次。 交付产品并收集用户反馈的第一部分，并特别注意产品支持。 如果检测到电路问题，请寻找解决问题的方法，然后转到第7项。如果找到软件错误，请寻找解决问题的方法，然后转到第12项。如果长时间成功使用， ，启动大量设备。

In the context of this plan, the development of device cases and mechanical parts tightly correlates with the development of circuitry. It should be carried out in parallel and follow the same process as the development of circuitry.

在该计划的背景下，设备外壳和机械零件的开发与电路的开发紧密相关。 它应并行进行，并遵循与电路开发相同的过程。

The development and prototyping of devices differ from software development greatly. The main reason for this is the lack of ability to quickly manipulate with the physical components of the device, as opposed to manipulations with virtual software components. Simply speaking, it is very difficult to make or rollback electronic device changes. It is much easier and faster just to make a device from scratch by applying the necessary changes to the scheme.

设备的开发和原型制作与软件开发大不相同。 造成这种情况的主要原因是与使用虚拟软件组件进行操作相反，缺乏使用设备的物理组件进行快速操作的能力。 简而言之，很难更改或回滚电子设备。 通过对方案进行必要的更改，使设备从头开始变得容易和快捷。

结论 (Conclusion)

Errors in hardware projects are as inevitable as in any other one. It is important to timely detect them and provide an adequate response to them. You shouldn’t be afraid of reissuing prototypes — it’s a common practice to achieve stable operation of the device’s hardware. To successfully finalize a device development, you will need transparent communication both inside the development team and with the customer. I hope this article has helped you to acquire basic skills and knowledge of the hardware manufacturing process. Good luck with hardware development and prototyping!

硬件项目中的错误与其他任何项目一样不可避免。 及时检测它们并对其做出适当响应很重要。 您不必担心会重新发布原型-这是实现设备硬件稳定运行的一种常见做法。 为了成功完成设备开发，您将需要开发团队内部以及与客户的透明沟通。 我希望本文能帮助您掌握硬件制造过程的基本技能和知识。 硬件开发和原型制作祝您好运！