1. The ability to learn quickly:
As a communication person, let me talk about communication equipment! On the one hand, communication technology, standards, and chips are updated so fast that you have no time to understand them systematically. You can only understand them through specific projects and requirements; on the other hand, for companies, the hardware products they need to make are also Changes are rapid. Customers need T1, E1, PDH, SDH, Ethernet, VoIP, Switch, Router. No one knows everything. They all need to be able to understand the selected chip solution in detail based on customer needs, especially for interface protocols. and electrical characteristics. Suppose you are in the power supply business. In the same way, you also need to have an in-depth understanding and study of power supply-related knowledge and customer needs, right?
2. Understanding of protocols and standards:
Continue to use communication equipment as a representative. Communication equipment, as the name suggests, is used to implement multiple communication protocols (such as T1, E1, V.35, PDH, SDH/SONET, ATM, USB, VoIP, WiFi, Ethernet, TCP/IP, RS232 and other common protocols) Communication equipment, various circuits, PCB boards, and power supplies all serve communication protocols.
Communication protocols are generally implemented by chips, either mature ASICs or self-developed FPGA/CPLD. Chip engineers or FPGA engineers are closer to communication protocols than hardware engineers. They need to understand communication protocols. It is very thorough and implements various logical state machines and meets the electrical parameter standards specified by the protocol. According to the OSI seven-layer model, hardware engineers especially need to focus on the protocol standards of the first-layer physical layer and the second-layer data link layer. Based on the Ethernet distance, the physical layer is completed by the PHY/transceiver chip, and the data link layer is completed by the MAC/ The switch chip is completed. For hardware engineers engaged in Ethernet-related development, they need to have a thorough understanding of PHY and Switch chips, from encoding methods, electrical parameters, eye diagram standards, templates, signal frequencies to frame formats, forwarding processing logic, VLAN, etc. .
This is especially true for traditional PDH/SDH/SONET equipment. PDH/SDH/SONET is a more hardware equipment, which means that the main protocols are implemented through ASIC, and the software functions are mainly management and configuration. , monitoring, alarming, performance. For hardware engineers, they must be familiar with the relevant protocols and interface standards used, especially electrical specifications and eye diagram templates, so that they can be confident during design verification.
If you work in smart home, you should have a deep understanding of the new standards of Bluetooth, WIFI, and Zigbee. You should also know the advantages and disadvantages of each. You can also know the improvements and disadvantages of the latest standards at your fingertips. , maybe this way you can make brand new products that meet consumer needs! It may also mean that when you change jobs, you will succeed because you have mastered a technology that others have not yet understood!
3. Ability to write documents:
Just like software design, good software design requires good design documents, clear requirements, what functions are implemented, what acceptance criteria are met, and then With the increase of chip integration, the increase of interface speed, the increase of single board complexity, the hardware design is becoming more and more complex, and the corresponding thermal stability, reliability, electromagnetic compatibility, and environmental protection requirements are no longer through Xiaomi Jiabumu. . The guerrilla war in the warehouse can be solved. Every hardware project is a war and requires good planning and analysis, which requires good documentation.
For hardware engineers, there are two most important documents: one is the hardware design specification (HDS: hardware design specification) and the hardware test report (generally called EVT: Engineering Validation; Test report or DVT: Design Validation & Test report), the requirements for HDS are detailed and clear content, main chip selection/hardware initialization, CPU selection and initialization, interface chip selection/initialization/management, block diagram of the connection relationship between each chip (Block Diagram), DRAM type/size/speed, FLASH type/size/speed, chip select, interrupt, GPIO definition, reset logic and topology diagram, clock/crystal selection/topology, use of RTC, memory map relationship , I2C device selection/topology, interface device/line sequence definition, LED size/color/driver, heat sink, fan, JTAG, power supply topology/timing/circuit, etc.
For DVT, the requirements are very simple and complex: what interfaces, chips, main components, circuits are on the board, what should be tested, especially the power supply when the board is working normally/ Voltage/ripple/timing, eye diagram/template of business interface, signal integrity and timing of internal data bus (such as MII, RGMII, XAUI, PCIe, PCM bus, Telecom Bus, SERDES, UART, etc.), CPU subsystem (Such as clock, reset, SDRAM/DDR, FLASH interface).
Good hardware engineers can make it clear at a glance, whether in documents or reports, what solutions and circuits are needed for this hardware system, and what are the results of the final verification test. The content is detailed and does not omit various interfaces/circuits; it is simple and clear, and does not talk nonsense; it is rich in pictures and texts. When needed, a timing diagram and an oscilloscope capture can explain the problem very well.
4. Ability to use instruments/software:
Instruments include soldering irons, multimeters, oscilloscopes, logic analyzers, bit error meters, transmission analyzers, and Ethernet testers Smartbits/ IXIA, calorimeter, attenuator, optical power meter, RF signal strength meter, etc.; software includes Office (Outlook, Word, Excel, PowerPoint, Project, Visio), PDF, commonly used schematic software Pads or OrCAD, commonly used PCB software Pads Or Allegro, Allegro Viewer, circuit simulation software PSPICE, signal simulation software HyperLynx, etc.
Both instruments and software are production tools in political economy and promote productivity improvement. As a hardware engineer, these instruments and software are like wood in your hands. Cangpao, a large part of the capabilities of hardware engineers are reflected in the use of instruments and software, especially the use of schematic software and oscilloscopes, which is very important. The use of schematic software is the specific realization of hardware design, through a The placement of each device and the connection of each NET constitute a very complex hardware logic software, which is the core work of the entire hardware design. The losses caused by any mistakes and errors on the schematic diagram are huge, and it is really "walking on thin ice" , trembling with fear."
In addition, the use of schematic diagram software is also reflected in the beauty of the schematic diagram. Good design is simple and clear, and the annotations are clear. No matter who is following the idea, they can quickly figure out the design intention. Special attention should be paid to bad design, one device in the east and another in the west, no logic, weird naming, difficult to understand, and very troublesome to maintain in the future; among all test instruments, the oscilloscope is the most important to hardware engineers, regardless of Both the schematic and the PCB are design work, but any design requires careful verification and testing, especially in terms of signals, which requires a lot of oscilloscope work. If you don't use the oscilloscope correctly, you can't even talk about correct verification. Is the ground connected properly? , The selection of test points, trigger selection, delay selection, amplitude and time selection all determine the test results. If the wrong use of the oscilloscope will inevitably lead to wrong test results, in this case, the originally wrong design may be mistaken for the correct one, bringing huge hidden dangers; the originally correct design may be mistaken for the wrong one, It brings a lot of waste of time and energy.
5. Circuit design capabilities:
With the improvement of chip integration, hardware design seems to have become simpler. The first is the logical connection, and secondly, the serial resistor selection and parallel capacitor selection required for signal integrity, power supply filtering, and decoupling are considered. However, for good hardware engineers, simple logical connections (the output of the same bus of this chip is connected to the input of another chip, etc.) are only the most basic skills of hardware design. The circuit is the chip function, communication protocol and various The carrier of the software does not have an in-depth understanding of the circuit, and there is no in-depth understanding of the hardware design at all, especially the understanding of the electrical performance parameters listed behind the chip or the various parameters of the discrete devices. If you connect them randomly, you may be stuck on the 3.3V bus. It can work, but now the working voltage has dropped to 1V. What is the concept? The noise on the signal line is already large enough to cause misjudgment in sampling. With the increase of signal rate and the decrease of working voltage, digital signals have become more and more It is becoming more and more analog, which requires an in-depth understanding of PCB impedance, capacitive reactance, inductive reactance, discrete devices (resistors, capacitors, inductors, diodes, transistors, MOSFETs, transformers, etc.), and ASIC interface electrical parameters. This all requires In-depth study of circuit principles, analog circuits and even electromagnetic field theory. Circuits can be said to be a subset of electromagnetic field theory. Without an understanding of electromagnetic field theory, there is no understanding of capacitance, inductance, crosstalk, and electromagnetic radiation.
Especially for the design of power circuits, chip voltages are now diversified, the voltages are getting lower and lower, and the currents are getting larger and larger. Operators have strict requirements for the power consumption and heat dissipation of communication equipment. For power supply design The challenges are getting bigger. It can be said that for a hardware design, 40% of the work is in the schematic/PCB design and post-test verification of the power circuit. The power circuit design is a concentrated expression of the circuit capabilities of the hardware engineer, including various passive devices, semiconductor devices, protection There are many parameters for devices and typical DC/DC conversion topologies, and the formulas need to be considered and calculated.
6. Ability to communicate and global control:
Hardware engineers generally play the role of team leader in a hardware project. They must be fully responsible for the hardware project and need to coordinate the PCB Engineers, structural engineers, signal integrity engineers, electromagnetic compatibility engineers and other resources, and work closely with product managers, project managers, software engineers, production engineers, procurement engineers to ensure that all links are on track and need to have a clear understanding of the entire project plan. chest, release time of each sub-task, estimation and control of possible technical difficulties and risks.
For the outside world, hardware engineers also need to have a good relationship with chip distributors and FAEs to strive for greater technical support and help; they also need to have good relations with EMC laboratories and external laboratories to obtain More flexible testing time and more suggestions for rectification.