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Introduction Everyone has heard of FPGA more or less, such as Bitcoin mining, or Microsoft said before that it will use FPGA instead of CPU in the data center. So what exactly is it? Why use it? Compared with CPU, GPU, and ASIC, what are the characteristics of FPGA? FPGA is a chip that can reconfigure circuits and is a hardware reconfigurable architecture. Through programming, users can change its application scenarios at any time, and it can simulate various parallel operations of hardware such as CPU and GPU. By interconnecting with the high-speed interface of the target hardware, the FPGA can complete the low-efficiency part of the target hardware, thereby achieving acceleration at the system level. What Is an FPGA? Catalog Introduction Ⅰ FPGA vs CPU vs GPU vs ASIC Ⅱ Five Advantages of FPGA 2.1 Performance 2.2 Time-to-Market 2.3 Cost 2.4 Stability 2.5 Long-Term Maintenance Ⅲ New Applications of FPGA Ⅳ Development Trend of FPGA Ⅴ FAQ Ⅰ FPGA vs CPU vs GPU vs ASIC The core difference between FPGA and CPU, GPU, ASIC chips, etc. is that the connection and logic layout of the underlying operation unit are not solidified. Users can program the logic unit and switch array through EDA software to configure the function, so as to realize the integration of specific functions.FPGA appears as a semi-custom circuit in the field of application-specific integrated circuits (ASIC), which not only solves the shortcomings of custom circuits, but also improves the limited number of original programmable device gate circuits. Compared with ASIC chips, an important feature of FPGA is its programmable characteristics, that is, the user can specify the FPGA to realize a specific digital circuit through the program. Furthermore, FPGA chips are one of the best choices for small batch systems to improve system integration and reliability. Figure 1. FPGA Basic Structure So why is FPGA so fast? This is all because the computer's CPU(central processing unit) and GPU(graphics processing unit) belong to the von Neumann structure, with instruction decoding and execution, and shared memory. FPGAs, on the other hand, are instruction-free and memory-free architectures that make FPGA chips much more energy-efficient than CPUs or even GPUs. Figure 2. Von Neumann Structure In the von Neumann architecture, since the execution unit (such as the CPU core) may execute any instruction, so an instruction memory, a decoder, an operator of various instructions, and branch and jump processing logic are required. Due to the complex control logic of the instruction stream, it is impossible to have too many independent instruction streams. Therefore, the GPU uses SIMD (single instruction, multiple data) to allow multiple execution units to process different data at the same pace, and the CPU also supports SIMD instruction. The function of each logic unit of the FPGA has been determined during reprogramming, and no instructions are required. Figure 3. Computer CPU If the GPU is used for acceleration, in order to fully utilize the GPU computing, the batch size cannot be too small, and the delay will be on the order of milliseconds. Using FPGA to accelerate, only microsecond-level PCle delay is required. Why is FPGA so much lower latency than GPU? This is basically an architectural difference. FPGAs have both pipeline parallelism and data parallelism, while GPUs have almost only data parallelism (with limited pipeline depth).For example, FPGA chips can change the running hardware design on the chip every few seconds, while chips such as CPU and ASIC are already solidified when they leave the factory and cannot be changed. If ASIC, CPU, GPU, etc. are built buildings, and the routes of rooms, corridors, and stairs in the building have been fixed, while the interior of FPGA is similar to the magic staircase in Hogwarts, which can change the route of room to room at any time. In addition, FPGA does not need to compile the instruction system at the software application level like CPU and GPU. To program FPGA, use hardware description language, and directly compile and burn it into a combination of transistor circuits, that is, directly use transistor circuits to implement user algorithms.The biggest feature of FPGA is its flexibility. It can realize any digital circuit you want and can customize various circuits. Reduce the shackles of special chips, truly tailor-made for your own products, you can flexibly change the design during the design process, and have field programmability, so it is especially suitable for applications that require continuous changes in physical operation logic, such as AI algorithm optimization, data center applications, etc. Architecture Throughput（int ops） Delay Flexibility CPU ~1T N/A Very High GPU ~10T ~1ms High FPGA(Stratix V) ~1T ~1us High FPGA(Stratix 10) ~10T ~1us High ASIC ~10T ~1us Low The FPGA is set up by the RAM stored on the chip to reset its working state, so the on-chip RAM needs to be programmed when working. Users can use different programming methods according to different configuration modes, which can be said to be very flexible and convenient. The FPGA has the following configuration modes:🔺Parallel Mode: Parallel PROM, Flash configures FPGA.🔺Master-Slave Mode: One PROM configures multiple FPGAs.🔺Serial Mode: Serial PROM configures FPGA.🔺Peripheral Mode: The FPGA is used as a peripheral of the microprocessor and programmed by the microprocessor. Computational performance compared with CPU: For example, Stratix series FPGAs perform integer multiplication operations, and their performance is equivalent to that of a 20-core CPU, and for floating-point multiplication operations, their performance is equivalent to an 8-core CPU.Computational performance compared with GPU: FPGA performs integer multiplication and floating-point multiplication operations. There is an order of magnitude difference in performance compared to GPU. The computing performance of GPU can be approached by configuring multipliers and floating-point operation components. Figure 4. CPU and GPU Architecture Diagram The core advantage of FPGA for performing computation-intensive tasks: tasks such as search engine sorting and image processing have strict requirements on the return time limit of results, and it is necessary to reduce the delay of computing steps. Under the traditional GPU acceleration scheme, the data packet size is large, and the delay can reach the millisecond level. Under the FPGA acceleration scheme, the PCIe latency can be reduced to the microsecond level. Driven by long-term technology, the data transmission delay between CPU and FPGA can be reduced to less than 100 nanoseconds.The FPGA can build the same number of pipelines (pipeline parallel structure) for the number of data packet steps, and the data packets can be output immediately after being processed by multiple pipelines. The GPU data parallel mode relies on different data units to process different data packets, and the data units need to be input and output consistently. For stream computing tasks, the FPGA pipeline parallel structure has a natural advantage in latency. FPGA is used to process communication-intensive tasks and is not limited by network cards. It outperforms CPU solutions in terms of packet throughput and delay, and has strong delay stability. Therefore, FPGAs have obvious advantages over CPUs when performing large data processing tasks with high repetition rates.By programming the FPGA, the user can change the internal connection structure of the chip at any time to realize any logic function. Especially in industries with immature technical standards or rapid development and change, FPGA can effectively help enterprises reduce investment risks and sunk costs, and is a functional and economical choice. Figure 5. Computer GPU With the evolution of intelligent market demand, highly customized chips (ASIC SoC) have led to a sharp increase in market risks due to the large scale of non-repetitive investment and long R&D cycle. Relatively speaking, FPGA has advantages in the field of parallel computing tasks, and can replace some ASICs in the field of high performance and multi-channel. The demand for multi-channel computing tasks in the field of artificial intelligence (AI) drives the evolution of FPGA technology to the mainstream. Figure 6. ASIC SoC Ⅱ Five Advantages of FPGA 2.1 Performance Taking advantage of hardware parallelism, FPGAs break the sequential execution model and complete more processing tasks per clock cycle, surpassing the computing power of digital signal processors (DSPs). BDTI(Big Data Test Infrastructure), a well-known analysis and benchmarking company, has published benchmarks that show that in some applications, FPGAs can handle many times more processing power per dollar than DSP solutions. Controlling input and output (I/O) at the hardware level provides faster response times and specialized functionality to meet application needs. 2.2 Time-to-Market Despite increasing time-to-market constraints, FPGA technology offers flexibility and the ability to rapidly prototype. Users can test an idea or concept and complete verification in hardware without going through the lengthy manufacturing process of custom ASIC design. This allows users to make incremental modifications and iterate FPGA designs in hours, saving weeks. Commercial off-the-shelf (COTS) hardware provides different types of I/O connected to user-programmable FPGA chips. The increasing popularity of high-level software tools reduces the learning curve and abstraction layers, and often provides useful IP cores (pre-built functions) for advanced control and signal processing. 2.3 Cost The non-recurring engineering (NRE) cost of custom ASIC design far exceeds the cost of FPGA-based hardware solutions. The huge initial investment in ASIC design shows that OEMs need to ship thousands of chips each year, but more end users need custom hardware capabilities that enable the development of tens to hundreds of systems. The nature of programmable chips means that users can save on manufacturing costs as well as long lead times for assembly. System requirements change from time to time, but the cost of changing the FPGA design is negligible compared to ASCI's huge expense. 2.4 Stability Software tools provide the programming environment, and FPGA circuits are the real "hard" implementation of programming. Processor-based systems often contain multiple layers of abstraction that can schedule tasks and share resources among multiple processes. The driver layer controls hardware resources, while the operating system manages memory and processor bandwidth. For any given processor core, only one instruction can be executed at a time, and processor-based systems face the risk of tightly time-bound tasks taking over each other at all times. FPGAs, on the other hand, do not use an operating system, and have true parallel execution and deterministic hardware that focuses on each task, reducing the chance of stability issues. 2.5 Long-Term Maintenance As mentioned above, FPGA chips are field-upgradable without the time and expense involved in redesigning ASICs. For example, digital communication protocols contain specifications that can change over time, and ASIC-based interfaces can create maintenance and forward compatibility difficulties. Reconfigurable FPGA chips can accommodate future modifications. As a product or system matures, users can enhance functionality without spending time redesigning hardware or modifying board layouts.   Ⅲ New Applications of FPGA At present, the FPGAs mainly produced by Xilinx and Altera with the highest market share, which are all based on SRAM technology, and need to be connected to an external memory to save the program when in use. When powered on, the FPGA reads the data in the external memory into the on-chip RAM, and after completing the configuration, it enters the working state. When power off, the FPGA returns to a white chip, and the internal logic disappears. In this way, the FPGA can not only be used repeatedly, but also does not require a special programmer, but only a general EPROM and PROM programmer. So Actel, QuickLogic and other companies also provide FPGAs with anti-fuse technology, which can only be downloaded once. They have the advantages of anti-radiation, high & low temperature resistance, low power consumption and fast speed. They are widely used in military and aerospace fields. FPGA cannot be erased and written repeatedly, which is troublesome and expensive in the early stage of development. Lattice is the inventor of ISP technology, which has certain characteristics in small-scale PLD applications. Early Xilinx products generally did not involve military and aerospace markets, but now a number of products such as Q Pro-R have entered such fields.In the industrial field, FPGA chips are widely used in the industrial field, and are widely used in video processing, image processing, CNC machine tools and other fields to realize signal control and operation acceleration functions. With the development of intelligence and automation technology, the industrial field is gradually shifting from human resources as the core element to intelligent unmanned factories with automation as the core element.Smart electric vehicles will be the mainstream development direction of the automotive industry in the future. At present, the application of FPGA in automotive cameras and sensors is relatively mature. In the artificial intelligence system of automatic/intelligent driving vehicles, the applicability of FPGA will be the most suitable for processing sophisticated ADAS and autonomous driving. Figure 7. FPGA for Auto In the field of automotive electronic system interface and control, FPGA chips are used to control and drive electric vehicle motor control systems, connect various in-vehicle equipment such as driving systems, instrument panels, radar, ultrasonic sensors, etc. control. In the field of video bridging and fusion, FPGA chips can be used to realize functions such as signal bridging of multiple image sensors, 3D surround view video fusion, reversing auxiliary video, and assisted driving video.In the field of communication, the number of 5G base stations has increased, and the FPGA usage of a single base station has increased, driving the increase in FPGA demand. According to estimates, the FPGA consumption of a 5G single base station is expected to increase from 1-3 blocks in the 4G period to 4-5 blocks in the 5G period. Figure 8. RFSoC FPGA Board Target 5G eFPGA technology is superior to traditional FPGA solutions in terms of performance, cost, power consumption, profitability, etc., and can provide flexible solutions for different application scenarios and different market segments. The economic trend of increasing design complexity and falling equipment costs has stimulated the market demand for eFPGA technology.   Ⅳ Development Trend of FPGA First of all, with the commercialization of the new generation of communication technology, the demand for products such as communication base stations, servers, and intelligent terminals will further expand, thereby driving the increase in the market demand for FPGA chips. At the same time, smart cities, smart factories, and consumer electronics pay more attention to the functionality of various smart IoT devices, which will drive the wide application of FPGA chips in smart IoT devices. With the development of the Internet of Vehicles technology, the scale of the use of FPGA chips in the automotive industry will increase day by day to build a more complete Internet of Vehicles and realize smarter autonomous driving functions. Therefore, with the rapid penetration of 5G, the vigorous development of AI and the increasing trend of automotive intelligence, it is expected that the demand for FPGAs in the three fields of communication, AI and automotive electronics will continue to increase in the future, which will also promote The FPGA industry continues to grow.   Ⅴ FAQ 1. What is FPGA and why it is used?The acronym FPGA stands for Field Programmable Gate Array. It is an integrated circuit that can be programmed by a user for a specific use after it has been manufactured. ... These blocks create a physical array of logic gates that can be customized to perform specific computing tasks. 2. Is FPGA faster than GPU?The difference between GPU and FPGA performance is not a static factor, but it does depend on the size of the data set. A study by Sanaullah and Herbordt [7] revealed that FPGA can compute small samples of 3D FFT tens of times faster than GPU. The difference is less clear when the data set gets bigger. 3. Is FPGA faster than CPU?A FPGA can hit the data cell faster and more often than a CPU can do it meaning the FPGA causes more results to occur during an attack. It all goes faster when an FPGA is used. And as a side benefit, no trace of all this is left on the CPU because it's never touched when an FPGA is used. 4. Are FPGAs efficient?Efficiency and Power: FPGAs are well-known for their power efficiency. A research project done by Microsoft on an image classification project showed that Arria 10 FPGA performs almost 10 times better in power consumption. 5. Is FPGA programming hard?FPGA vendors have touted their wares as ideal replacements for DSPs, CPUs, and GPUs – even for all of them in a single device – but they are notoriously difficult for software engineers to program as they are not anything like a conventional processor. 6. What can you do with FPGAs?Uses for FPGAs cover a wide range of areas—from equipment for video and imaging, to circuitry for computer, auto, aerospace, and military applications, in addition to electronics for specialized processing and more. 7. What is the difference between processor and FPGA?Microprocessor vs FPGA: A microprocessor is a simplified CPU or Central Processing Unit. ... An FPGA doesn't have any hardwired logic blocks because that would defeat the field programmable aspect of it. An FPGA is laid out like a net with each junction containing a switch that the user can make or break. 8. What language is used to program FPGA?VerilogTraditionally, FPGAs are programmed using pro-level hardware-description languages such as Verilog or VHDL. 9. How many times can you program an FPGA?There is effectively no limit to the number of times a device can be reconfigured; the configuration is stored in SRAM, which has no write limit. most Fpgas can be passively loaded from a processor, one word at a time. That processor can get the FPGA image from anywhere. 10. What are the advantages of FPGA?FPGA advantagesLong-term availabilityUpdating and adaptation at the customerVery short time-to-marketFast and efficient systemsAcceleration of softwareReal-time applicationsMassively parallel data processing 11. How do you make an FPGA?FPGA design checklistMake sure you have plenty of time to spare.Find a decent computer.If you can afford it, add a big display.Decide which operating system to use.Consider using a virtual machine (VM).Select an FPGA vendor.Pick out a suitable development board.Select an embedded processor to use. 12. What is FPGA for beginners?FPGA stands for Field Programmable Gate Array. As you may already know, FPGA essentially is a huge array of gates that can be programmed and reconfigured any time anywhere. Huge array of gates is an oversimplified description of FPGA. FPGA is indeed much more complex than a simple array of gates. 13. What is FPGA in Verilog?FPGAs are nothing, but reconfigurable logic blocks and interconnects can be programmed by Hardware Description Language like Verilog/ VHDL to perform a specific functionality. 14. Do we need to program the FPGA once powered off?If you have a SRAM-based FPGA, like the Spartan 3, then you have to program it each time it is powered up. The reason for this is that the SRAM which stores the configuration is volatile and loses the programmed configuration after power is switched off. 15. How is FPGA different from microcontroller?One of the main differences between a microcontroller and an FPGA is that an FPGA doesn't have a fixed hardware structure, while a microcontroller does. While FPGAs include fixed logic cells, these, along with the interconnects, can be programmed in parallel by using HDL coding language.

CatalogIntroductionⅠ What is a Microcontroller（MCU）?Ⅱ The History of the Microcontroller (MCU)Ⅲ The Classification and Application of MCUⅣ China MCU Technology and Well-known ManufacturersⅤ  The Basic Functions of MCUⅥ Learning Methods - Using MCUⅦ Six Main Dimensions of MCU Products for Future ImprovementⅧ Programming of MCUⅨ Summary of the MCU Programming EngineerⅩ How to Develop MCU Ⅺ 5 Tips to Solve the Questions About the MCU CrystalⅫ Summary of Chip OperationFAQIntroductionA microcontroller (MCU) is a small computer built on a single metal-oxide-semiconductor (MOS) integrated circuit (IC) chip. A microcontroller is made up of a CPU  (processor core), memory, and programmable input/output peripherals. On chip, a small amount of RAM, as well as ferroelectric RAM, NOR flash, or OTP ROM , is commonly included. Microcontrollers  , in contrast to microprocessors  used in personal computers  or other general-purpose applications, are designed for embedded applications and are made up of a number of discrete chips. This article will delve deeper into the MCU.Ⅰ What is a Microcontroller（MCU）? Microcontroller UnitThe microcontroller unit (MCU) appropriately reduces the frequency and specifications of the CPU  and integrates peripheral interfaces such as memory, counter, USB, A/D conversion, UART, PLC, and DMA. At the same time, even the LCD driver circuit is integrated on a single chip to form a chip-level computer, which can be controlled in different combinations for different applications, such as mobile phones, PC peripherals, remote controls, automotive electronics, industrial stepping motors, machines The control of the arm, etc., can be seen in the MCU.Figure 1 MCU componentsⅡ The History of the Microcontroller (MCU)Microcontroller Unit has a short history, but it has evolved quickly. Its generation and development are roughly synchronized with that of microprocessors  (CPUs). Since Intel Corporation of the United States first introduced 4-bit microprocessors  in 1971, its evolution can be roughly divided into five stages. The following is an overview of the development of Intel's MCU.1971-1976  The initial stage of MCU developmentIn November 1971, Intel introduced the Intel 4004, a 4-bit microprocessor with an integration level of 2000 transistors/chips and equipped with RAM, ROM, and shift registers, which served as the first MCS-4 microprocessor. The Intel 8008 8-bit microprocessor was introduced, followed by other 8-bit microprocessors  from various companies.1976-1980  Low-performance MCU stageThe MCS-48 series, introduced by Intel Corporation in 1976, has a monolithic structure that integrates an 8-bit CPU.  an 8-bit parallel I/O interface, an 8-bit timer/counter, RAM, and ROM on a semiconductor chip. Its addressing range is limited (no more than 4 KB), there is no serial I/O, the RAM and ROM capacity is limited, and the interrupt system is simple, but its functions can meet the needs of general industrial control and intelligent instruments and meters.1980~1983  High-performance MCU stageHigh-performance 8-bit microcontrollers introduced at this stage typically include serial ports, multi-level interrupt processing systems, and multiple 16-bit timers/counters. The capacity of the on-chip RAM and ROM  is increased, and the addressing range can reach 64 KB. A/D conversion interfaces are also available on individual chips. 1983~late 1980s  16-bit microcontroller stage.In 1983, Intel introduced a high-performance 16-bit microcontroller MCS-96  series. The chip integration level was as high as 120,000 transistors/chips due to the use of the most recent manufacturing process.1990sCPUs are developing to a higher level in all directions, such as integration, function, speed, reliability, and application fields. Ⅲ The Classification and Application of MCUMCUs are classified into two types based on their memory type: those with no on-chip ROM  and those with on-chip ROM,  The chip without on-chip ROM  must be used externally with EPROM (typically 8031); the chip with on-chip ROM  is classified as on-chip EPROM (typically 87C51), MASK on-chip mask ROM  (typically 8051), on-chip Flash (typically 89C51), and other types.MCUs are classified into two types based on their intended use: general-purpose and special-purpose. It is classified into4, 8, 16, and 32-bit MCUs based on the width of the data bus and the number of data bytes that can be processed at the same time.Figure 2 MCU product category At present, the most widely used MCU market in China is in the consumer electronics  field, followed by the industrial field and the automotive electronics  market. Consumer electronics  include home appliances, televisions, game consoles, and audio and video systems. Industrial fields include smart homes, automation, medical applications, and new energy generation and distribution. The automotive field includes automotive powertrains and safety control systems. Industrial MCU Industrial MCU products  are primarily used for motor control operation, data acquisition control, and other functions in motor control, instrumentation, low-voltage power distribution, power tools, industrial robots, and other application scenarios.Figure 3 Electric-Vehicle-ChargerThe number of MCU devices is increasing as the complexity of industrial equipment increases. Consider industrial robots: at least ten MCU products  are used in a single industrial robot.Home Appliance MCU MCU is widely used in household appliances, mainly used to realize system control, motor control, panel display control, and other functions.The home appliance market is mainly divided into small household appliances and everyone electricity, small household appliances including kitchen appliances (microwave oven, induction cooker, soybean milk machine, etc.), household appliances (vacuum cleaner, electric fan, electric heater, etc.), personal life small household appliances (electric toothbrush, hairdryer, etc.), everyone electricity mainly for air conditioning, refrigerator, washing machine, and other white appliances.Figure 4 Induction-heating-cooker-app-block-diagramAt the moment, 32-bit MCUs have become the market's mainstream due to their higher specifications and performance, as well as their constantly decreasing cost, and are widely used in automotive electronics.  industrial control/medical, and other fields; however, there are still a large number of application scenarios requiring simple control, and low-value MCUs have cost advantages, so they continue to occupy a large market.BitApplication4Calculator, auto instrument, auto anti-theft device, pager, wireless phone, CD player, LCD dynamic controller, children's toys, scales, chargers, Tire gauge, thermometer, remote control, etc8Electrical appliances, ammeter, motor controller, electric toy machine, pager, fax machine, telephonograph, keyboard and USB, etc16Mobile phones, digital cameras and video recorders, etc32Smart home, IoT, motor and frequency conversion control, security monitoring, fingerprint identification, touch keys, Modem, GPS, STB, Workstation, ISDN telephone, laser printer and color fax machine, etc64Advanced workstation, multimedia interactive system, advanced TV game instrument, advanced terminal, etc.According to IC Insights, the global MCU market is about 16.4 billion dollars in 2019 and could reach about 20 billion dollars by 2023.The scale of China's MCU market was about 25.6 billion yuan in 2019, accounting for about 26% of the global market, with a compound growth rate of 9% from 2015 to 2019.In terms of the global market, the auto circuit accounts for 33% of the global MCU market. According to IC Insights data, the automotive MCU market space will reach $8.1 billion in 2023, the overall growth rate is considerable; At the moment, 32-bit MCUs have become the market's mainstream due to their higher specifications and performance, as well as their constantly decreasing cost, and are widely used in automotive electronics.  industrial control/medical, and other fields; however, there are still a large number of application scenarios requiring simple control, and low-value MCUs have cost advantages, so they continue to occupy a large market.Figure 5  MCU Market StructureFrom the perspective of pattern, the top five global automotive MCU market shares in 2020 were Renesas, NXP, Infineon, Texas Instruments and Microchip, accounting for 87% in total.Ⅳ China MCU Technology and Well-known ManufacturersMCU market is still dominated by overseas leaders, and Chinese high-quality manufacturers are gradually making breakthroughs in the segmented fields, and their share is expected to increase rapidly under the background of accelerated localization in China.The global MCU market is expected to grow further, with the global MCU market size reaching $16.4 billion in 2019 and $20 billion in 2023.On the demand side, improvements in automotive electrification, accelerated IoT  penetration, increased demand for intelligent frequency conversion in home appliances, rapid iteration of wearable devices, and steady growth in industrial control continue to drive the rapid growth of the MCU industry. (Using MCU as an example, the global market compound growth rate from 2020 to 2023 is 7.7 percent, and the market space is expected to be 8.1 billion dollars by 2023)On the supply side, the MCU industry is experiencing a continuous shortage due to the epidemic in 2020. Infineon, NXP.  and ST  , as well as other overseas MCU large factories, have appeared several times to dozens of times the price, with delivery times of more than 50 weeks; persistent shortages are expected to last at least through the end of 2021 and the first quarter of 2022.In terms of circuit barriers, the requirements of automobile circuits in the MCU downstream field are the highest, followed by industrial and home appliance circuits, and the relative requirements of consumer electronics  are slightly lower, according to MCU product environmental temperature, yield, and service life, and other parameters.According to the industry competition pattern, Chinese MCU manufacturers have a low market share, benefit from accelerated replacement due to stock shortages in the short term, and have ample room for improvement in the long term:The global MCU market is more concentrated, with a microchip, ST  MICROELECTRONICS, Renesas, TI, NXP  , Infineon, and other manufacturers occupying more than 80% of the market share; China's MCU market is approximately 25 billion yuan, and the total market share of domestic MCU manufacturers is less than 12%, primarily concentrated in the consumer market, which has ample room for expansion.The shortage of goods leads to the acceleration of the pace of China's MCU manufacturers, in the automotive, industrial, and consumer circuit, the pace of China's MCU certification continues to accelerate. Renesas Electronics - the world's first automotive MCU manufacturer Renesas was founded in 2003 by the merger of Hitachi Semiconductor division and Mitsubishi Electric Semiconductor division. Its main business covers automotive, industrial, communications, and other fields. Renesas is the world's first automotive MCU manufacturer, accounting for 30% of the automotive MCU market in 2020.Renesas MCU has a complete product line covering EV/HEV, powertrain, electric vehicle, vehicle dashboard, vehicle network, chassis control, ADAS, and other application fields.Microchip technology -8 bit MCU main features, acquisition of Atmel to supplement the strength of 32 bit MCUMicrochip Technology Corporation (Microchip) was founded in 1989, Microchip technology is the world's leading supplier of single-chip and analog semiconductors. The company's main business is the microcontroller, memory products, analog interface, and mixed information products, technology licensing, and so on.The products are mainly used in embedded control systems and IoT-related industries, including data processing, Medical Internet + (IoT), smart city, Industry 4.0, intelligent healthcare, etc. Major customers include Intel, Dell, Lockheed Martin, HP, Boeing, etc. STST -ARM architecture MCU king ST was founded in 1987, its products are mainly used in automotive products, computer peripherals, communication systems, consumer products, industrial automation control systems, and other aspects. Its major customers include Apple, blackberry, Bosch, Cisco, Conti, HP, Nokia, Obata, Samsung, and Western Digital.MCU vehicle grade products accounted for 32.13% of the company's revenue. St holds 8.5% of the current MCU market and is the leader in the segmented 32bitMCU  market.ST has been deeply engaged in the automotive semiconductor field for many years, and the company has a complete industrial chain, its products have a very high-cost performance ratio, and occupy a dominant position in the MCU of vehicle regulation level. Its customers include Nissan, Audi, SAIC, Tesla, and many other companies. NXP - the world's leading automotive MCU manufacturer NXP Semiconductor was founded in 2006. It was formerly the semiconductor division of Philips. NXP's main business is MCU, MPU, and other products, which can be widely used in automotive electronics  , industrial control, smart city, smart home, and wearable products. Its MCU/MPU based on the S32 automotive platform has obvious advantages in safety and efficiency and has been adopted by mainstream OEMs around the world.The industry's first crossover MCU was independently developed by NXP: I. MX RT series. Such products have been recognized by many Internet platforms (such as Amazon) for their high integration, cost performance, and security.NXP's acquisition of Freescale (founded by MOTOROLA) in 2015 gives it a deeper presence in the automotive industry. In 2020, 47% of its revenue came from vehicle MCU. At present, the company accounts for 27.8% of the global automotive MCU industry, ranking second in the world. NXP  provides complete semiconductor solutions for intelligent vehicles including automotive entertainment systems, Advanced Driver Assistance Systems (ADAS). Sino Wealth Electronics - China's largest home appliance MCU manufacturer Sino Wealth Electronic Ltd. is an MCU integrated circuit design company, the main products include 8-bit Flash MCU, 8-bit OTP/Mask MCU, 16-bit  DSP , 4-bit OTP/Mask MCU, widely used in household appliances, automotive, industrial control, security, and other fields;In the field of small household appliances, the company's competitors are mainly ABOV from Korea and Holtek from Taiwan. In the field of white household appliances, the company's competitors are mainly from Europe and America, including Renesas, NEC, TI, STM, and so on. Ⅴ The Basic Functions of MCUInternal-function diagramFor most MCUs, the following functions are the most common and basic. The description methods for different MCUs may differ, but the essence is essentially the same.1. Timer: Although there are many different types of Timers, they can be divided into two categories. The first is a Timer with a fixed time interval, which means that its timing is set by the system and cannot be controlled by the user program. The system only provides a few different types of Timers. The user program is given a fixed time interval, such as 32Hz, 16Hz, 8Hz, and so on. Because Timers of this type are relatively common in 4-bit MCUs,they can be used to implement clock, timing, and other related functions.The other type is Programmable Timer. The timing of this type of Timer can be controlled by the user's program. The control methods include the selection of the clock source, the selection of the prescale number, and the setting of the preset number, etc. There are Most MCUs have all three at the same time, and some may have one or both of them. This kind of Timer application is very flexible, and the actual use is also ever-changing. One of the most common applications is to use it to achieve PWM  output.Since the clock source can be freely selected, such Timers are generally combined with the Event Counter.2. IO port: Any MCU has a certain number of IO ports. Without IO ports, the MCU will lose the channel of communication with the outside world. According to the configurable situation of the IO port, it can be divided into the following types:Pure input or pure output : This type of IO port is determined by the MCU hardware design, and can only be input or output, and cannot be set in real-time by software.3. Directly read and write IO port: For example, the IO port of MCS-51 belongs to this type of IO port. When the read IO port command is executed, it is an input port; when the write IO port command is executed, it is automatically an output port.Program programming to set the direction of input and output: the input or output of this type of IO port is set by the program according to the actual needs, the application is more flexible, and can realize some bus-level applications, such as12C bus, various LCD, LED Driver control bus, etc.When using the IO port, this point must be kept in mind: for the input port, there must be a clear level signal to ensure that it cannot be floated (this can be achieved by adding a pull-up or pull-down resistor); and for the output port, the output state level must be Considering its external connection, it should be ensured that there is no source current or sink current in Standby or static state.External interrupts: External interrupts are a basic function of most MCUs. They are commonly used for real-time signal generation, data sampling, and state detection. Rising edge, falling edge, and level triggering are all interrupting methods. In most cases, the external interrupt is handled via the input port. If it is an IO port, the interrupt function will only be enabled when it is set as an input port; if it is set as an output port, the external interrupt function will be automatically closed (with some exceptions in ATMEL's ATiny series, where the output port can also trigger the interrupt function). The application of external interrupt is as follows:Detection of external trigger signals: One is based on real-time requirements, such as thyristor control, detection of sudden signals, and so on, while the other is based on power savings.Measurement of signal frequency:: To ensure that the signal is not missed, an external interrupt is the best option.Decoding data: To reduce design costs in the field of remote control applications, it is frequently necessary to use software to decode various encoded data, such as Manchester and PWM encoding.Button detection and system wake-up: In order for the MCU to enter the Sleep state, it must be woken up via an external interrupt. The most basic form is a button, and the level change is caused by the button's action.4. Communication interface: The communication interface provided by MCU generally includes SPI interface, UART. I2C interface, etc., which are described as follows:SPI interface: This type of interface is the most basic communication method provided by most MCUs. Its data transmission is controlled by a synchronous clock. The signals include SDI (serial data input), SDO (serial data output), SCLK (serial clock), and Ready signal; in some cases, there may be no Ready signal; this type of interface can work in Master mode or Slave mode, the popular saying is to see who provides the clock signal, the party providing the clock is the Master, and the opposite party It is Slaver.UART（Universal Asynchronous Receive Transmit）：It belongs to the most basic asynchronous transmission interface. Its signal lines only have two Rx and Tx lines. The basic data format is: Start Bit + Data Bit(7-bits/8-bits) + Parity Bit(Even， Odd or None) + Stop Bit(1~2Bit). The time occupied by one bit of data is called Baud Rate .For most MCUs, the length of data bits, data check mode (odd check, even check or no check), Stop Bit length and Baud Rate can be flexibly set through program programming. Certainly. The most common way of this type of interface is to communicate with the serial port of the PC.I2C interface: I2C  is a data transmission protocol developed by Philips. It also uses two signals to implement: SDAT (serial data input and output) and SCLK (serial clock). The biggest advantage is that multiple devices can be attached to this bus, and they can be identified and accessed through addresses; one of the biggest advantages of the I2C  bus is that it is very convenient to use software to implement through the IO port, and the data rate of its transmission is completely controlled by SCLK. To control, it can be fast or slow, unlike the UART  interface, which has strict rate requirements.5. Watchdog: Watchdoga basic configuration of most MCUs, can only allow the program to reset it but not close it (some are set when the program is burned in, such as Microchip PIC  series MCUs), while some MCUs are It is determined by a specific method whether it is turned on or not. For example, in Samsung's KS57 series, as long as the program accesses the Watchdog  register, it is automatically turned on and cannot be turned off again. Generally speaking, the reset time of the watchdog can be set by the program. The most basic application of Watchdog  is to provide a self-recovery ability for the MCU to crash due to unexpected failure.Ⅵ Learning Methods - Using MCUThe basic principles and functions of any MCU are similar. The only difference is the configuration and quantity of its peripheral function modules and the instruction system.For the instruction system, although it seems to be different in form, it is only a difference in symbols, and the meanings it represents, the functions to be completed, and the addressing modes are similar.To learn about an MCU, the first thing you need to know is its ROM space, RAM space, number of IO ports, number of timers and timing methods, peripheral function modules (Peripheral Circuit) provided, interrupt sources, operating voltage, and power consumption, etc.After understanding these MCU Features, the next step is to compare the functions of the selected MCU with the required functions of the actual project development and clarify which resources are currently required and which are not used in this project.For the functions that need to be used in the project but are not provided by the selected MCU, it is necessary to carefully understand the relevant information of the MCU, to use an indirect method to achieve it. For example, the developed project needs to communicate with the COM port of the PC, and If the selected MCU does not provide a UART  port, it can be implemented through external interrupts.For the resources needed for project development, you need to carefully understand and read the Manua*, while for the unneeded function modules, you can ignore or browse. For MCU learning, the application is the key and the main purpose.For beginners or designers who use this MCU for the first time, they may encounter a lot of ambiguous descriptions of the functions of the MCU. For this kind of problem, there are two ways to solve it, one is to write a special verification program to understand the functions described in the data; the other can be ignored for the time being. Leave it to modify and improve when debugging. The former method is suitable for projects with loose time and beginners, while the latter method is suitable for those who have some experience in single-chip development or when the project schedule is more urgent.Don't take the time to learn the command system in particular. The instruction system is simply a logical description symbol. During programming, you can only check the relevant instructions in accordance with the logic requirements of the program. As your programming skills improve, you will become more proficient in the instruction system.Ⅶ Six Main Dimensions of MCU Products for Future ImprovementStronger computing performance: MCU towards 500Mhz main frequency, MPU increase more processor cores;Additional wireless connection functions: More RF modules have been integrated.Low power consumption, high energy efficiency ratio: integrated analog chip, and low power analog peripheralsContinued support for hardware accelerators: high integration of algorithms and toolsSafety: improve anti-interference ability and safetyCost-effective: reduce costⅧ Programming of MCUThe programming of MCUs and PCs differ significantly. Although C-based MCU development tools are becoming more popular, assembly language remains the most concise and efficient programming language for designers who are efficient program code and like to use assembly.Circuit diagram to build your own microcontroller programmerThe basic framework for MCU programming is roughly the same, divided into the initialization part (the biggest difference between MCU programming and PC programming), the main program loop body, and the interrupt handler. as shown below:1.Initialization: The most basic and important step in the design of all MCU programs is an initialization, which generally includes the following:Mask all interrupts and set the stack pointer to In general, the initialization section does not want any interruptions to occur.Clearing the system's RAM and displaying the Memory: Although it is not always necessary, it is recommended to develop good programming habits for the sake of reliability and consistency, particularly to avoid accidental errors.IO port initialization: Set the input and output modes of the relevant IO port based on the project's application requirements. Set the pull-up or pull-down resistance for the input port, and the initial resistance for the output port.Interrupt setup: Enable and set interrupt trigger conditions for all interrupt sources required by the project, and close unnecessary interrupts that are not used.Initialization of other functional modules: For all peripheral functional modules of MCU that need to be used, corresponding Settings must be carried out according to the application requirements of the project. For example, Baud Rate, data length, verification mode and Stop Bit length should be set for communication of UART  , and clock source should be set for Programmer Timer. Frequency and Reload Data, etc.Initialization of parameters: after completing the initialization of MCU hardware and resources, the following is the initialization of some variables and data used in the program. This part of initialization needs to be designed according to the specific project and the overall arrangement of the program. For some applications that use EEPROM to store the number of prefab items, it is recommended to copy the relevant data to THE RAM of MCU during initialization to improve the speed of data access and reduce the power consumption of the system (in principle, access to the external EEPROM will increase the power consumption of the power supply).2.Main program loop body: Most MCUs run continuously for a long time, so their main program bodies are basically designed in a looping manner. For applications with multiple working modes, there may be many Each loop body is converted between each other through state flags. For the main program body, the following modules are generally arranged:Calculation procedures: Calculation procedures are generally time-consuming, so it is strongly opposed to processing in any interrupt, especially multiplication and division operations.Processing programs with low or no real-time requirements;Display transfer program: mainly for applications with external LED and LCD Driver.3. Interrupt handler: The interrupt program is mainly used to handle tasks and events with high real-time requirements, such as detection of external sudden signals, detection, and processing of buttons, timing counting, LED display scanning, etc.Under normal circumstances, the interrupt program should keep the code as concise as possible. For functions that do not need to be processed in real-time, the trigger flag can be set in the interrupt, and then the main program executes the specific transaction - this is very important, especially for low-power, low-speed MCUs, is necessary to ensure timely responses to all interrupts.4. There are various MCU processing methods for various task bodies.For example, for low-speed, low-power MCU (Fosc=32768Hz) applications, considering that such projects are handheld devices and use ordinary LCD, the response to buttons and display response requires high real-time performance, so generally Timed interrupts are used to process button actions and data display; for high-speed MCUs, such as Fosc>1MHz applications, since the MCU has enough time to execute the main program loop body at this time, it can only be interrupted at the corresponding Various trigger flags are set in the program, and all tasks are executed in the main program body.5. In MCU programming, special attention should be paid to:Avoid situations where the same variable or data is accessed or set in both the interrupt and the main body. The effective prevention method is to arrange the processing of such data in a module, and decide whether to execute the relevant operation of the data by judging the trigger flag; In other bodies (mainly interrupts), only the trigger flag is set where the processing of the data is required. This ensures that data execution is predictable and unique.Ⅸ Summary of the MCU Programming EngineerTo develop a good habit of summarizing, summarizing is not only a summary of their learning, but also a review and deepening of the learning process, but also to avoid the second error.Before writing the program, we should have a solid understanding of the project so that we can start with a solid idea and a general framework. It is critical to consider the layout and what makes the most sense. To determine which module should be completed first, specific steps for the module, how to name each function, and the relationship with other modules. Take a piece of paper and scribble down significant progress.For C language modular programming, we should first divide each module, a module programming, determine a sequence, and then write the next module based on the success of the previous one. When it comes to header files, write the module's header file after you've finished writing the module.Do not ignore the fact that the program must be unreasonable to comprehend its origins and find a solution. When looking for a source, it should be pertinent; you can search for relevant data on the Internet or consult with others. For example, the primary function of another project was incorporated into this project. Some functions are named multiple times. Step by step analysis of the cause, also according to the experimental phenomenon. When defining the port, the incorrect interface was selected. When you can't solve a problem, it's sometimes good to take a break. Things can go wrong no matter how simple they seemThe problems of code utilization efficiency, anti-interference, and MCU reliability continue to plague MCU application development. Ⅹ How to Develop MCU 1How to reduce program bugsThe following are the over-arching management parameters that should be considered during system operation in order to reduce program bugs.Physical parameters: These are primarily system input parameters that include excitation parameters, acquisition and processing operating parameters, and result parameters at the end of processing.Resource parameters: These are primarily the resources of the system's circuits, devices, and functional units, such as memory capacity, storage unit length, and stacking depth.These application parameters are frequently expressed as the application conditions of some single-chip microcomputers and functional units. The term "process parameter" refers to a parameter that changes in an orderly manner during the system's operation.2How to improve the efficiency of C language programming codeIt is an inevitable trend of the development and application of MCU to use C language to design MCU. If you are programming in C, it is best to be familiar with the C compiler you are using to achieve maximum efficiency. First test the number of statement lines in the assembly language corresponding to each C language compilation, so that you can clearly know the efficiency. When programming in the future, use the statement with the highest compilation efficiency. Each C compiler will have certain differences, so the compilation efficiency will also be different. The code length and execution time of an excellent embedded system C compiler is only 5-20% longer than the same functional degree written in assembly language.C language can be used for complex and time-critical projects, but the premise is that you are very familiar with the C language and C compiler of the MCU system and that you pay special attention to the data types and algorithms that the C compiler system can support. Although C is the most commonly used high-level language, the C language compilation system varies due to MCU manufacturer differences, particularly in the operation of some special function modules. As a result, if you don't understand these features, you'll have a lot of trouble debugging, which will result in lower execution efficiency than assembly language.3 How to Solve the MCU Anti-Interference ProblemThe most effective way to prevent interference is to remove interference sources and cut off interference paths, but this is often difficult to do, so we can only conclude that MCU's anti-interference ability is insufficient. While improving the anti-interference capability of hardware systems, software anti-interference has received increasing attention due to its flexible design, ability to save hardware resources, and high reliability.As for the program run fly, in fact, can also use software trap and watchdog to pull the program back to reset state, so the MCU software anti-interference is the most important to deal with the reset state.In most cases, MCU will have some sign registers that can be used to determine the reason for the reset; alternatively, you can bury some tokens in RAM yourself. Different reset causes can be determined in each program reset by judging these signs. You can also use different flags to jump directly to the corresponding program. In this manner, the program will run indefinitely, and the user will be unaware that it has been reset.4How to test the reliability of the MCU systemWhen a MCU system design is completed, there will be different test items and methods for different MCU system products, but some must be tested:lTest the completeness of the software functions of the MCUlPower-on and power-off testlAging testlTests such as ESD and EFT Sometimes, we can also simulate the damage that may occur in human use. For example, the contact port of the MCU system is intentionally rubbed with the human body or clothing fabric, thereby testing the antistatic ability. Use a high-power electric drill to work close to the MCU system to test the anti-electromagnetic interference ability.To sum up, the MCU has become an important aspect of the development and application of the computer.Most of the functions that must be realized by analog circuits or digital circuits in the past can now be realized by software methods using a single-chip microcomputer. This control technology in which software replaces hardware is also called micro-control technology, which is a revolution of traditional control technology.In addition, in the process of development and application, we must master the skills and improve the efficiency, so as to facilitate its wider use.Ⅺ 5 Tips to Solve the Questions About the MCU CrystalCrystal oscillator for MCUCommon causes of the crystal can not vibratePCB wiring error;Microcontroller quality issues;Crystal vibration quality issues;The load capacitance or matching capacitance does not match the crystal oscillator or the capacitor quality is incorrect;PCB board damp, resulting in impedance mismatch and inability to vibrate;The crystal oscillator circuit is too long;There is a line between the feet of crystal;Influence of peripheral circuit.You are advised to rectify faults one by one as follows: 1Remove the possibility of circuit error so that you can compare the recommended circuit of the corresponding type of microcontroller.2 Rule out the possibility of poor peripheral components; because peripheral components are nothing more than resistance and capacitance.3Rule out the possibility of using a crystal oscillator as a stop oscillator because you will not be experimenting with just one or two crystal oscillators.4Try changing the capacitor at both ends of the crystal; perhaps the crystal oscillator will begin to vibrate; please refer to the crystal oscillator capacitor size instructions.5In PC  B wiring, crystal oscillator circuit wiring should be as short as possible and as close to IC as possible, not between crystal oscillator feet. Ⅻ Summary of Chip OperationThe operation of the chip is mainly the operation of the registers in the chip. The registers in the chip have their unique address mapped on the memory, which is the operation of the corresponding address. To learn the chip, first look at the sequence diagram, then understand the corresponding registers, understand how to operate, define the required port (the program can recognize), write and read the operation program.Cross-sectional-views-of-chip-operationHow data is written to the chip, how it is read out, and through which port it is input or read.When connecting a chip through a bus, the first step is to understand the protocol of the bus. The chip connected to the I2c bus is controlled by the bus.1One 74HC595 lattice is used for column selection, and the other two are used for color selection. The lattice is equivalent to a set of diodes.The diode lights up only when one end is switched to a high level and the other to a low level. Just one end of the selection of different, bright different colors.Timer working mode selection: Set timer T1 in the high four digits and timer T0 in the low four digits. Then the last two characters of each mode set the working mode. When using interrupts, note that after entering the interrupt, the reset should be reset.2Serial port transceiver: Baud rate is generally set in mode 2 (automatic reloading initial value) because different devices have different data processing capabilities, the baud rate is set mainly to take care of low-speed devices and for communication between each other. The interrupt flag bit should be cleared by the software. When setting the serial port interrupt, either sending or receiving can enter the interrupt function, so pay attention to setting the interrupt function. (Self-sense generally sets a function, as the upper machine or lower machine).If you send interrupts, you have to figure out how to enter interrupts the first time, so you send them once and then you can enter interrupts. Only one byte can be sent at a time, and only after TI is set to one can the next byte be sent.3Pcf8591ad conversion, there are four channels of input, read PC  F8591, which channel, read is that channel input voltage, after the conversion of data stored in the chip, then read. Read to write the address of the chip, the son writes device address (0 x40 | channel number) and then reads the data.4Da conversion is to write the device address into the chip first, then write the sub-address (0x40) and then write the digital quantity to be converted. Device address chip information is introduced.5For the liquid crystal display, write data display, he will always display, do not continue to refresh, to change, only re-input.6For THE DS1302 clock chip, reading data is read out of the first data at the falling edge of the eighth clock when writing data, and then prepare for the next output. Pay attention to the writing of the program, but also pay attention to the position of the return value.7In Ds1302, the register is specified first, and then data is written to it. The registers on the chip data indicate the address. 8Initialization is best to write, in case you forget later. When reading or writing, the first operation is the lowest or highest bid, which can be judged according to the sequence diagram.9For the infrared transceiver, receiving, he is according to the length of time between the two falling edges to determine the high level or low level, write a program, first with the timer to determine the length of time, save, and then into binary (the program written to see more, very good).10Stepper motor: mainly used as switches, stepper motor torque decreases with the increase of speed. It is mainly used for automatic feeding of parts processing on machine tools. It can also be used in high-precision control places.Stepper motor is an open-loop control element stepper motor that converts electric pulse signal into angular displacement or linear displacement. In the case of the overload, motor speed, stop position depends only on the pulse signal frequency and pulse number, and are not affected by load change, when the stepper driver receives a pulse signal, it is driving a stepper motor according to set the direction of a fixed Angle, known as the "step Angle", its rotation is based on the Angle of the fixed step by step. The angular displacement can be controlled by controlling the number of pulses to achieve accurate positioning. At the same time, the speed and acceleration of the motor can be controlled by controlling the pulse frequency, achieving the purpose of speed regulation.11Servo motor : Servo motor refers to the engine that controls the operation of mechanical components in a servo system. It is an indirect transmission device for auxiliary motors. Servo motors can control speed, position accuracy is very accurate, voltage signal can be converted into torque and speed to drive the control object. Servo motor rotor speed is controlled by the input signal, and can respond quickly, in the automatic control system, used as an executive element, and has the characteristics of mechanical and electrical time constant is small, high linearity, starting voltage, etc., can receive the electrical signal into the motor shaft angular displacement or angular velocity output. It is divided into DC and AC servo motors. Its main characteristic is that when the signal voltage is zero, there is no rotation phenomenon, and the speed decreases uniformly with the increase of torque.12Chinese Characters overview: To output Chinese characters on display or printer, Chinese characters are designed into a dot matrix graph according to graphic symbols, and corresponding dot matrix codes (glyphs) are obtained.The unified encoding for the representation of Chinese characters in the computer is called the internal code (such as national code), and the internal code is unique (equivalent to the id number of the character). The encoding of Chinese characters formed to facilitate the input of Chinese characters is the input code, which belongs to the external code of Chinese characters. The input code varies with the encoding mode and is diverse. The Chinese character code formed for displaying and printing Chinese characters is the character code, and the computer finds the character code in the character library through the character code and realizes its conversion.Machine code: According to the GB code, each Chinese character has a certain binary code, but this code will conflict with THE ASCII code when handled internally by the computer. To solve this problem, the first byte of each GB code is incremented by 1. Because ASCII code only uses 7 bits, the "1" on the first digit can be used as a symbol to identify Chinese character codes. When the computer processes the code with the first digit of "1", it will be interpreted as the information of Chinese characters, and when it processes the code with the first digit of "0", it will be interpreted as the ASCII code. After such processing, the national code (internal code) is the machine's internal code.If put this "mouth" word graphic "." With "0" instead, you can very vividly get the "mouth" glyphs :0000H 0004H 3FFAH 2004H2004H 2004H2004H 2004H2004H 2004H2004H 2004H 3FFAH 2004H 0000H 0000H. Computer to output "mouth", find shows that character first address, according to the "mouth" machine code after calculation, to find a "mouth" glyph code, and then according to the glyph code (to) in binary character generator, in turn, scan control on the screen, which is where the "0" of the binary empty, is a place where "1" swept out of the window, Then you get the character graph of the mouth.Chinese characters are arranged according to the order of national standard codes and stored in the memory in the form of binary files, which constitute the Chinese character font library, also known as the Chinese character font library, called the Chinese character library1312864 liquid crystal: Each display point corresponds to a binary number, with 1 indicating on and 0 indicating off. The RAM that stores this lattice information is called the display data memory. To display a graph or Chinese character is to write the corresponding lattice information into the corresponding storage unit.When the horizontal address = 0FH, it will be reset to 00H, but it will not automatically add one to the vertical address. Therefore, when writing multiple data in a row, the program needs to determine whether the vertical address needs to be reset14GDRAM: Drawing display RAM provides 128×8 bytes of memory space. When changing the drawing RAM, the horizontal and vertical coordinate values are successively written, and then two bytes of data are written to the drawing RAM. The address counter (AC) will automatically increment the horizontal address (X address) and reset to 00H when the horizontal address is 0XFH. Vertical addresses will not be carried automatically plus 1. The drawing display must be turned off during writing to the drawing RAM,For C, a defined variable is automatically allocated space and its address is the name of the variable. Through this name, the data can be recruited in memory, and the new data can be obtained through an operation. In assembly, the programmer needs to define the storage space and send the data to the accumulator for operation, and the programmer needs to operate every step. In C, this is done by the compiler.FAQ1. What is the main function of microcontroller?Microcontroller is a compressed micro computer manufactured to control the functions of embedded systems in office machines, robots, home appliances, motor vehicles, and a number of other gadgets. A microcontroller is comprises components like - memory, peripherals and most importantly a processor.2. What is an example of a microcontroller?The examples of 8-bit microcontrollers are Intel 8031/8051, PIC1x, and Motorola MC68HC11 families. The 16-bit microcontroller performs greater precision and performance as compared to the 8-bit.3. What are the elements of a microcontroller?Therefore, the microcontroller must also satisfy the five basic elements of input, calculation, storage, output, and control. These are called five elements of microcontrollers.4. Which is best microprocessor or microcontroller?If you need access to large amounts of really fast memory then a microprocessor is likely your best option. A microcontroller is already embedded with memory so the memory choices are fewer than with a microprocessor. The maximum amount of FLASH memory available with most microcontrollers is usually around 2MB.5. What is difference between BIOS and CMOS?The BIOS is the program that starts a computer up, and the CMOS is where the BIOS stores the date, time, and system configuration details it needs to start the computer. ... CMOS is a type of memory technology, but most people use the term to refer to the chip that stores variable data for startup.6. Is CMOS a RAM or ROM?RAM and ROM are the products, but Complimentary Metal Oxide Semiconductor (CMOS) is the process they are built in. CMOS uses two different types of transistors to achieve a lower overall power consumption.7. Whats an RTC battery?The Real Time Clock (RTC) battery provides power for the internal clock/calendar and for maintaining system configuration settings. This error can occur when a machine has been left turned-off for an extended period of time (approximately one to four months), and it is the result of a depleted RTC battery.            

Introduction Do you use Raspberry Pi? or What are doing with it? Is it a microcontroller (MCU for microcontroller unit) or microcomputer? or SoC (system-on-chip)? As a beginner, is it better to buy a microcontroller or a Raspberry Pi? Look at the following content. Raspberry Pi Explained Catalog Introduction Ⅰ Basic Definition Ⅱ Raspberry Pi vs MCU Ⅲ What Can We Do with Raspberry Pi? Ⅳ Where do I start to Learn Raspberry Pi? Ⅴ FAQ Ⅰ Basic Definition Raspberry Pi is actually a tiny embedded computer. It uses ARM microcontroller chip, and linux operating system or windows. It can regard as a small desktop computer when connects with a monitor, keyboard, and network (network port or wifi). With the release of Windows 10 IoT, Raspberry Pi can also run Windows.The single-chip microcomputer refers to the central processing unit core with some peripheral interface circuits on it, which is also called the microcontroller unit (MCU), or SoC. 8051 chips, avr chips, arm chips, etc. are all called single-chip microcontrollers, while Intel’s 80x86 series are central processing unit (CPU) and cannot be called MCU.It uses very large-scale integrated circuit technology to integrate the central processing unit CPU with data processing capabilities, RAM, ROM, multiple I/O ports and interrupt systems, timers/counters and other functions (may also include display driving circuits, pulse width modulation circuits, analog multiplexers, A/D converters and other circuits) are integrated on a silicon chip to form a small and complete microcomputer system. It is widely used in the field of industrial control. Figure 1. Raspberry Pi Setting Ⅱ Raspberry Pi vs MCU Next, let's take a look at the difference between the Raspberry Pi and the MCU and introduce in detail what can we do with the Raspberry Pi?The single-chip microcomputer is an microcontroller, and the Raspberry Pi is a single-board computer with arm-architecture processor. Early MCUs were peripherals for ROM and IO with slow speed, and it could not run time-sharing operating systems such as Linux or Windows. But the Raspberry Pi can run an operating system like Linux, or deploy servers or cloud computing. That is, the Raspberry Pi can perform many operations that cannot be done by a single-chip microcomputer.The size of the single-chip microcomputer is relatively small, and the internal chip is used as a computer system. Its structure is simple, but the function is perfect, it is very convenient to use, and it can be modularized. The most important thing is that although the development cycle of the single-chip microcomputer is relatively short, it is basically based on a specific task and the code must be re-programmed every time, which is very troublesome.The Raspberry Pi is actually a computer motherboard. It can be programmed, compiled, and run directly locally. If you want to add or delete functions to the original program, or switch from the current task to a different new task, you do not need to burn programs like a single-chip microcomputer according to different tasks or updates. Use Raspberry Pi to control peripherals by operating GPIO basically through various libraries, and if you connect it to the Internet, you can operate it remotely. Figure 2. Raspberry Pi GPIO In general, each has its own advantages. The MCU is cheap and suitable for general consumer products. After all, the Raspberry Pi is a card-type computer with an embedded operating system running on it. That is, a low-power general-purpose computer. For electronic geeks, the back-end data processing and GUI for complex control systems are still very good for satisfying embedded learning. Ⅲ What Can We Do with Raspberry Pi? After reading the above, since Raspberry Pi has the features of a computer, this means you’re able to do most things a desktop computer can do such as document editing, playing HD video, playing games, coding and much more.Obviously it won’t have as much power as a desktop PC but since it is a lot cheaper they make for great little computers you can play around with.Here lists some items you can do:1) Wireless HotspotUsing the Internet cable and USB wireless network card, after configuration, it can be used as a wireless hotspot.2) Mechanical ProsthesesMIT Media Lab researchers use it as a controller for mechanical prostheses.3) Easy Homemade NotebookConnect the Raspberry Pi to the LCD panel, add the mouse, keyboard and power supply, and find a beautiful case and put it on, finally it becomes a simple homemade notebook.4) WiFi CarAn IBM engineer installed it on a model car, and then used WiFi signals to control the car’s actions.5) Send Dynamics RemotelyWeather enthusiasts tied it to a detection balloon and used it to send a tweet in the stratosphere.6) Control Door SwitchThere are also people who use the Raspberry Pi to control the garage door and combine it with Siri to remotely control the garage switch.7) Surveillance ShootingA camera is connected as a small shooting device, which is small in size and easy to hide.8) Back Up EmailsOne of the most important functions of my Raspberry Pi is to back up emails. Use a software called getmail to check every mail using POP or IMAP protocol, and check the mail of each account regularly. Then save the email to an mbox file, which can be copied to another computer at any time for long-term email archiving.9) Build a RSS ReaderMiniflux, a self-hosted web-based RSS client that can be installed on the Raspberry Pi. Like many people, when Google announced that it would close Google Reader on July 1st, I also started to migrate personal data. I used rss2email for a while and let it send every item of RSS to my mailbox. But in fact, I don't like this method very much, so I spent some time looking for alternatives to Google Reader and tried rss2email and found miniflux finally. Installing miniflux on the Raspberry Pi is very simple, you only need to install PHP and a web server software in advance, such as nginx or Apache.10) Build a WebsiteOne obvious use of Raspberry Pi is as a backend server for websites. Because it has enough capacity to handle static websites, some web frameworks are not a problem. I built a Flask framework on it, and I even heard that some people built a Wordpress directly on the Raspberry Pi.11) Home Network StorageOnly consumes very low power, Raspberry Pi can become a perfect NAS (Network Attached Storage). Before I connected a 500GB laptop hard drive to the Raspberry Pi and installed an operating system on it. I can store many files on it that need to be transferred between different computers. Then connect via SFTP, you can access it on any machine at home (even if you are not at home, it will not be a problem as long as the routing settings are correct). You can also install Samba on your Pi so that both Mac and PC can access it more easily.12) Site MonitoringUse Raspberry Pi is to detect websites that are important to me. I wrote a Python script and ran it regularly to make sure that these websites responded with a 200 status code (which means everything is normal). If the script determines that there is a problem with the website or cannot be accessed, it will email me the overall situation of the incident. The Python module I use is Requests, and the email module is smtplib.13) Event ReminderUse Raspberry Pi to email me important events that I need to remember. I used Google Calendar before, but I only use it for simple events. So I replaced it with a Raspberry Pi, and a Python script for timed tasks is enough. I set the date, time, and message to remember. These parameters will be passed to my Python script, and on that day it will send the message to my mailbox to remind me of the day’s events.14) Family AlbumMy Raspberry Pi also supports a private website that contains all my family photos. I set up verification information so only people I want them to see can enter the site. This is much more reliable than your Facebook photo album, because your account on Facebook may be deleted, and the photos will be seen by strangers by chance. Here is a method, just use PHP to get the photos in a folder on the Raspberry Pi.15) JukeboxI mentioned above that I use Pi as a network storage, so all my music is also on it. I connected a stereo speaker to my Pi and used mpg123 to play music on the command line of the Raspberry Pi. Although there are many other mp3 players and graphical interfaces, I still choose mpg123 because it is easy to install and use. Figure 3. Raspberry Pi Projects Ⅳ Where do I start to Learn Raspberry Pi? If you are really interested in it and want to get started. How, and what do you need? 1) A Raspberry Pi. So, obviously you’ll need he actual board. If you don’t have it, you cant really do what you want. So find a website or store and buy one. Depending on the type and model you get, they can range from as low as 10$ to 50$. Pretty affordable.2) A monitor. So, you don’t actually need a monitor. But it is going to be so much easier. You can actually buy displays the Pi company has made specifically made for the Pi. These however are a little more expensive.You could also use your TV as a monitor, providing both the TV and the Pi can be hooked up via HDMI. VGA to HDMI would work too. Many different solutions can be used when it comes to the cable you use for a monitor, or all around screen. Adapters come in all shapes, sizes and forms. 3) A power source. You’ll need to power the Pi to use it. Most of the time, you will get a little charger to use with the Pi. Using this specific charger will probably be the best, as it will always pull enough power from the wall into your Pi.4) A mouse, and keyboard. You will need a mouse and keyboard. This is pretty much mandatory. Well, only for the actual screen portion of the Pi. Models 3 B+ and up have built in Bluetooth, so you can have cordless mouse and keyboard if you would like. That’s pretty cool.5) Depending on the model, you will need an Ethernet cable to have internet. Models 3 B+ and up have a built in WiFi chip. So you can have a wireless internet connection if you so please.6) A microSD card with the image you want to use. When you buy the Pi, you will need to have an SD card. The newer models use microSD cards. Putting the SD card into the Pi without anything on it wont do anything though, you'll need an image. Images for the Pi can be found along the internet for downloads. The standard image used for the Pi right now is NOOBS Debian.7) Time, patience and dedication. These are very important when working with the Pi. Why? Because the Pi is powerful, yet it can be confusing at times, especially for a “noob”.   Ⅴ FAQ 1. What is Raspberry Pi mainly used for?The Raspberry Pi is a low cost, credit-card sized computer that plugs into a computer monitor or TV, and uses a standard keyboard and mouse. It is a capable little device that enables people of all ages to explore computing, and to learn how to program in languages like Scratch and Python. 2. What are some good Raspberry Pi projects?Best Raspberry Pi Projects for BeginnersMusic Streaming.Security System.Weather Station.Arcade Machine.NAS.Digital Photo Frame.Retro Handheld Console.Robot. 3. Can a Raspberry Pi run Windows?The Raspberry Pi 4 can handle Microsoft Edge, the calculator app, and more, all via the power of Windows 11. It can even run Minecraft, albeit in an undesirable state. 4. Can Raspberry Pi go on Internet?If you want to connect your Raspberry Pi to the internet, you can plug an Ethernet cable into it (if you have a Raspberry Pi Zero, you'll need a USB-to-Ethernet adapter as well). If your model is a Raspberry Pi 4, Raspberry Pi 3, or Raspberry Pi Zero W, you can also connect to a wireless network. 5. How do I setup a Raspberry Pi network?Configuring the Raspberry Pi Ethernet Port With a Static IP.Step 1: Review Current Network Settings.Step 2: Backup the Current Network Configuration.Step 3: Modify the Network Settings. To edit the network setting you must edit the dhcpcd.Step 4: Restart the Raspberry Pi.Step 5: Test the New Network Setup. 6. How is Raspberry Pi different from microcontroller?The main difference between them is: Arduino is microcontroller board, while Raspberry Pi is a microprocessor based mini computer (SBC). The Microcontroller on the Arduino board contains the CPU, RAM and ROM. 7. Is Raspberry Pi zero a microcontroller?A Raspberry Pi is not a microcontroller, it is a single board computer. Neither. The chip itself is an SOC or system on chip, so it has almost all the parts of a computer on a single die. 8. Is the Raspberry Pi a system on a chip?Raspberry Pi SBCs feature a Broadcom system on a chip (SoC) with an integrated ARM-compatible central processing unit (CPU) and on-chip graphics processing unit (GPU), while Raspberry Pi Pico has a RP2040 system on chip with an integrated ARM-compatible central processing unit (CPU). 9. Can you use a microcontroller with a Raspberry Pi?Meet the Raspberry Pi Pico, a tiny little microcontroller that lets you build hardware projects with some code running on the microcontroller. Unlike computers, microcontrollers don't run traditional operating systems. 10. Is Raspberry Pi 3b a microcontroller?The Raspberry Pi is a single board computer with Microprocessor whereas Arduino is considered as Microcontroller unit. The Raspberry Pi can run an OS (Linux Distribution) and also consumes more power. Since Arduino is microcontroller device it has no operating system and can only run a single program or sketch. 11. What is Raspberry Pi used for in IoT?How can IoT Applications use Raspberry Pi? With an in-built quadcore processor, Raspberry Pi can serve as the “Internet Gateway” for IoT devices. Powered by a cloud network, Pi acts as a web server for uploading and transiting sensor data on IoT platforms. 12. What is the difference between microprocessor and microcontroller?KEY DIFFERENCESMicroprocessor consists of only a Central Processing Unit, whereas Micro Controller contains a CPU, Memory, I/O all integrated into one chip. ... Microprocessor uses an external bus to interface to RAM, ROM, and other peripherals, on the other hand, Microcontroller uses an internal controlling bus. 13. What kind of computer is Raspberry Pi?The Raspberry Pi is a low cost, credit-card sized computer that plugs into a computer monitor or TV, and uses a standard keyboard and mouse. It is a capable little device that enables people of all ages to explore computing, and to learn how to program in languages like Scratch and Python. 14. Can I use a Raspberry Pi as my main computer?Aside from the hard drive crash, the Raspberry Pi was a perfectly serviceable desktop for web browsing, writing articles, and even some light image editing. ... 4 GB of ram is just enough for a desktop. My 13 Chromium tabs, including a Youtube video, are using just over half of the 4 GB of available memory. 15. Which OS is better for Raspberry Pi?Raspbian. Raspbian is a Debian-based engineered especially for the Raspberry Pi and it is the perfect general-purpose OS for Raspberry users.

Ⅰ Introduction RFID is a technology that uses electromagnetic fields to automatically recognize and track tags attached to objects. An RFID system is composed of a small radio transponder, a radio receiver, and a radio transmitter. Catalog Ⅰ Introduction Ⅱ RFID Related Video: Ⅲ RFID Chip 3.1 WHAT IS RFID? 3.2 HOW DOES RFID WORK? 3.3 What Are the Types of RFID Systems  ? Ⅳ RFID Tags 4.1 Definition of RFID Tags 4.2 How RFID Tags Work？ 4.3 Examples of RFID Tags Ⅴ What Does (RFID Reader) Mean? 5.1 What exactly is an RFID Reader  ? 5.2 Readers Types Ⅵ Blocking Wallet 6.1 What Is an RFID-Blocking Wallet? 6.2 How Do RFID-Blocking Wallets Work? 6.3 The 5 Best RFID-Blocking Wallets Ⅶ RFID Asset Tracking  7.1 What Is RFID Asset Tracking  ? 7.2 How Does RFID Asset Tracking  Work? Ⅷ RFID Vs. NFC: The 5 Key Differences Ⅸ FAQ   Ⅱ RFID Related Video:   How RFID Works? and How to Design RFID Chips?     RFID Related Video Description: In this video, we learn about how RFID works and we see how RFID chips are designed. The main concepts such as backscatter modulation and energy harvesting is explained in detail. We start by explaining the RFID technology, in particular passive RFIDs.We discuss the operation of RFID and the magnetic field coupling.Then we look inside the RFID tags and locate the RFID chip and antenna inside the tags.Then we see how RFID chips are designed and explain all different parts of the chip in detail.We discuss the backscatter modulation as well as RF frequencies used in RFID communication.At the end we also provide some information about RFID readers.     Ⅲ RFID Chip 3.1 WHAT IS RFID? RFID is an abbreviation for "radio-frequency identification," and it refers to a technology that uses radio waves to capture digital data encoded in RFID tags  or smart labels (defined below). RFID is similar to barcoding in the sense that data from a tag or label is captured by a device and stored in a database. RFID, on the other hand, has several advantages over systems that use barcode asset tracking software. The most notable difference is that RFID tag data can be read even when the tag is not in direct view, whereas barcodes must be aligned with an optical scanner. If you are thinking about implementing an RFID solution, contact the RFID experts at AB&R® (American Barcode and RFID).   3.2 HOW DOES RFID WORK? RFID systems are made up of three parts: a scanning antenna  , a transceiver, and a transponder. An RFID reader  or interrogator is a device that combines the scanning antenna  and the transceiver. RFID reader  s are classified into two types: fixed readers  and mobile readers  . RFID reader  s are network-connected devices that can be portable or fixed. It transmits signals that activate the tag via radio waves. When activated, the tag sends a wave back to the antenna.  which converts it into data. The RFID tag contains the transponder. RFID tag read range varies depending on factors such as tag type, reader type, RFID frequency, and interference in the surrounding environment or from other RFID tags  and readers,  Tags with a more powerful power source have a greater read range.   3.3 What Are the Types of RFID Systems  ? RFID systems are classified into three types: low frequency (LF), high frequency  (HF), and ultra-high frequency (UHF) (UHF). Microwave RFID technology is also available. Frequencies differ greatly depending on country and region. RFID systems with low frequency. These frequencies range from 30 kHz to 500 KHz, with 125 KHz being the most common.  LF RFID  has relatively short transmission ranges, ranging from a few inches to less than six feet. RFID system with high frequency  These range from 3 MHz to 30 MHz, with 13.56 MHz being the most common HF frequency. The typical range is from a few inches to several feet. RFID  UHF  systems These have a frequency range of 300 MHz to 960 MHz, with a typical frequency of 433 MHz, and can be read from a distance of 25 feet or more. RFID systems that use microwaves These operate at 2.45 Ghz and can be read from a distance of more than 30 feet.   Ⅳ RFID Tags 4.1 Definition of RFID Tags RFID tags are a type of tracking system that uses intelligent barcodes to identify items. RFID stands for "radio frequency identification," and RFID tags  make use of radiofrequency technology. These radio waves send data from the tag to a reader, which then sends the data to an RFID computer program. RFID tags  are commonly used to track merchandise, but they can also be used to track vehicles, pets, and even Alzheimer's patients. An RFID tag is also known as an RFID chip. 4.2 How RFID Tags Work？ An RFID tag transmits and receives data via an antenna  and a microchip, which is also known as an integrated circuit or IC. The RFID reader  's microchip is programmed with whatever information the user desires. What exactly is an RFID tag? RFID tags are classified into two types: battery-powered and passive. Battery-operated RFID tags.  as the name implies, use an onboard battery as a power source, whereas passive RFID tags  do not, instead of relying on electromagnetic energy transmitted from an RFID reader,  RFID tags  powered by batteries are also known as active RFID tags,  Passive RFID tags  transmit data at three different frequencies: 125–134 KHz, also known as Low Frequency (LF), 13.56 MHz, also known as High Frequency (HF) and  Near-Field Communication  (NFC), and 865–960 MHz, also known as Ultra High Frequency (UHF) (UHF). The range of the tag is affected by the frequency used. When a reader scans a passive RFID tag, it sends energy to the tag, which powers it up enough for the chip and antenna  to relay information back to the reader. The reader then sends this data to an RFID computer program for interpretation. Passive RFID tags  are classified into two types: inlays and hard tags. Inlays are typically thin and can be adhered to a variety of surfaces, whereas hard tags are, as the name implies, made of a hard, durable material such as plastic or metal.Transponders are much more battery-efficient than beacons because they only activate when they are close to a reader. Figure1:antenna 4.3 Examples of RFID Tags Because an active RFID is constantly transmitting a signal, it is an excellent choice for those seeking real-time trackings, such as in tolling and real-time vehicle tracking applications. They are a costly product, but they have a long read range, which may be preferred depending on the application. Passive RFID tags.  which cost around 20 cents each, are a much more cost-effective option than active  RFID tags ,  As a result, they are a popular choice for applications such as supply chain management, race tracking, file management, and access control. While a passive RFID tag does not require a direct line of sight to the RFID reader.  its read range is much shorter than that of an active RFID tag. They are small, lightweight, and have the potential to last a lifetime. Active RFID tags are better suited for applications requiring durability because they have a larger, more rugged design than passive RFID tags,  They are commonly used in toll payment transponder systems, cargo tracking applications, and even personal tracking devices. Figure2:Examples of RFID Tags Ⅴ What Does (RFID Reader) Mean? 5.1 What exactly is an RFID Reader  ? A radio frequency identification reader (RFID reader) is a device that collects data from RFID tags that are used to track individual objects. Data is transferred from the tag to a reader using radio waves. RFID is a technology that, in theory, is similar to bar codes. The RFID tag, on the other hand, does not have to be scanned directly, nor does it need to be in direct line of sight of a reader. To be read, the RFID tag must be within the range of an RFID reader.  which can range from 3 to 300 feet. RFID technology allows several items to be scanned quickly and allows for quick identification of a specific product, even when it is surrounded by several other items. RFID tags have not replaced bar codes due to their high cost and the requirement to individually identify each item.   5.2 Readers Types A passive reader in a Passive Reader Active Tag (PRAT) system only receives radio signals from active tags (battery operated, transmit only). A PRAT system reader's reception range can be adjusted from 1–2,000 feet (0–600 m), providing flexibility in applications such as asset protection and supervision.   An active reader in an Active Reader Passive Tag (ARPT) system transmits interrogator signals and receives authentication responses from passive tags. Active tags activated by an interrogator signal from the active reader are used in an Active Reader Active Tag (ARAT) system. A Battery-Assisted Passive (BAP) tag, which acts like a passive tag but has a small battery to power the tag's return reporting signal, could also be used in this system.Fixed readers  are configured to create a specific interrogation zone that is tightly controlled. This allows for a well-defined reading area when tags enter and exit the interrogation zone. Handheld mobile readers  are available, as well as those mounted on carts or vehicles.   Ⅵ Blocking Wallet If you have RFID-enabled cards, passports, or devices, an RFID-blocking wallet may be necessary to protect your data.   6.1 What Is an RFID-Blocking Wallet? Thieves can steal your credit card information just by standing next to you if you don't have an RFID-blocking wallet. It is possible if you carry a credit card with an RFID chip embedded in it. RFID credit cards allow you to make payments by simply touching the card to a scanner rather than swiping it across or inserting it into a terminal. They're made for ease of use. Imagine someone approaching you and "scanning" the wallet in your back pocket without your knowledge. They could theoretically copy the RFID data and create a clone of your credit card unless it is protected by an RFID-blocking wallet.   6.2 How Do RFID-Blocking Wallets Work? RFID chips have been a source of concern for many years, and not just in credit cards. RFID chips in all US passports issued after 2006 track your photo and information. RFID chips are embedded in metro cards for quick swiping, and RFID chips are implanted in dogs for tracking. RFID chips communicate by using radio waves. An RFID tag with information is embedded in the object, such as a credit card, and an RFID reader  uses radio waves to read the information from the tag. The key point is that RFID chips have tiny electromagnetic fields, which allows them to be read without having to "initiate" communications. The RFID reader  only needs to be close enough to the field to work. As a result, someone could theoretically scan a card through your pocket. And, yes, people have been scanned in the real world in this manner. Check out this Reddit anecdote to see what kind of headache RFID hackers can cause. Fortunately, radio waves can be easily interrupted and blocked, which is how an RFID-blocking wallet works. They encase your credit cards in a radio-interfering material. If the wallet is constructed properly as a Faraday cage, it will block all electromagnetic fields and prevent communication between your cards and RFID scanners. But do YOU really require an RFID-blocking wallet? Most likely not. If your credit cards do not have RFID chips, you obviously do not require one. Even if you do have RFID-enabled cards, the chances of being scanned maliciously are extremely low—-less than 1%, according to some. On the other hand, the possibility exists at all times, and the probability is non-zero.   6.3 The 5 Best RFID-Blocking Wallets Saddleback Passport WalletBig Skinny Slimline WalletTrayvax Original WalletSharkk Rugged WalletRadix One Black Steel   Ⅶ RFID Asset Tracking  As a company that depends on the availability of high-value assets to generate revenue, you understand the significance of asset tracking and effective inventory management. Whether it's inventory, tools, IT equipment, vehicles, or even employees. 7.1 What Is RFID Asset Tracking  ? RFID asset tracking is a technique for automating the management and location of physical assets. It works by loading data onto an RFID tag and attaching it to a relevant asset. This information can range from name, condition, amount, and location. An RFID reader  can capture the stored data by using the RFID tag's repeatedly pulsating radio waves. Eventually, it will be collected in a sophisticated asset tracking system, where the data can be monitored and acted upon. The ability to automate your tracking and monitoring processes seeks to eliminate the highly error-prone methods of pen-and-paper and excel spreadsheets.Among other benefits such as: Tracking multiple assets at any one timeEliminating human interventionCollecting data in real-timeImproving asset visibilityLocating lost or misplaced assetsMaximising accuracy of inventory   7.2 How Does RFID Asset Tracking  Work? The basic principles of how an RFID tracking system works are very similar whether it is used in agriculture to track livestock or in a warehouse to monitor a manufacturer's supply chain. First, you'll need the right tools: RFID Tags (Passive, Active, or Semi-Passive)An AntennaAn RFID ReaderA computer database equipped with Asset Tracking Software The RFID asset tracking process can be divided into four stages once the proper equipment is in place: The data is stored on an RFID tag that has a unique  Electronic Product Code  (EPC) and is attached to an asset. An antenna  detects a nearby RFID tag's signal. An RFID reader is wirelessly connected to the antenna  and receives the data stored on the RFID tag. The data is then transmitted by the RFID reader to an asset tracking database, where it is stored, evaluated, and acted upon. The initial process is relatively simple, depending on how you choose to deploy your RFID asset tracking system. However, there are a variety of factors to consider when selecting the right hardware.   Ⅷ RFID Vs. NFC: The 5 Key Differences Even though both technologies appear similar on the surface, there are five key differences between them. The Reading Range NFC technology operates on a limited range, also known as proximity. RFID, on the other hand, can read tags from up to 10 meters away, making it the best solution for vehicle identification and access. Check out our Automatic Vehicle Identification Guide if you want to learn more about long-term solutions. Communication Because NFC is capable of two-way communication, it can provide novel and complex solutions such as card emulation and peer-to-peer. Speed With NFC technology, unlike RFID tags.  only one tag can be read at a time. As a result, RFID tags are often better suited to environments with a high concentration of trackable components. Asset management in a manufacturing facility or tracking fast-moving vehicles is two examples. Data NFC technology stores and transmits a variety of data types. NFC devices, with their larger storage capacity, can store and transmit more data than RFID devices, which can only carry simple ID information. As a result, NFC is better suited to environments where payment details, membership, and ticket information, among other things, must be transferred. The cost-effectiveness NFC-based readers  are less expensive than long-range RFID solutions due to their limited reading range. As a result, NFC is an excellent choice for businesses on a tight budget who still require a high-quality solution. Ⅸ FAQ 1. Can you be tracked through RFID? The answer was an electronic lock, and the company has given its handful of employees the option of using an electronic key or getting an RFID chip implanted in their arm. "It can't be read, it can't be tracked, it doesn't have GPS," Darks said. 2. Can RFID be hacked? RFID hackers have demonstrated how easy it is to get hold of information within RFID chips. As some chips are rewritable, hackers can even delete or replace RFID information with their own data. ... It's easy to purchase the parts for the scanner, and once built, someone can scan RFID tags and get information out of them. 3. Why is RFID bad? The other problem with RFID chips versus, say, embedded smart chips is that as wireless devices they don't need to be near the reader to be read. Smart chips, on the other hand, need to be put next to, or into, a reader, so they aren't as susceptible to being sniffed in the open. 4. How is RFID powered? Active RFID tags have a transmitter and their own power source (typically a battery). ... Instead, they draw power from the reader, which sends out electromagnetic waves that induce a current in the tag's antenna. Semi-passive tags use a battery to run the chip's circuitry, but communicate by drawing power from the reader. 5. What is RFID example? For example, an RFID tag attached to an automobile during production can be used to track its progress through the assembly line, RFID-tagged pharmaceuticals can be tracked through warehouses, and implanting RFID microchips in livestock and pets enables positive identification of animals. 6. How do I know if I have an RFID chip? The best way to check for an implant would be to have an X-ray performed. RFID transponders have metal antennas that would show up in an X-ray. You could also look for a scar on the skin. Because the needle used to inject the transponder under the skin would be quite large, it would leave a small but noticeable scar. 7. Do credit cards have RFID? RFID-enabled credit cards - also called contactless credit cards or “tap to pay” cards - have tiny RFID chips inside of the card that allow the transmission of information. ... Though many new credit cards are RFID-enabled, not all of them are. On the other hand, all newly-issued credit cards come with an EMV chip.

2026 Executive Summary: Reading SMD Resistor CodesHow do you read SMD resistor codes? For standard 3-digit codes, the first two numbers are significant digits, and the third is the multiplier (10^x). For 4-digit codes (precision), the first three are significant. The EIA-96 system uses a two-digit code and a letter multiplier. This authoritative guide covers all calculation methods, updated for 2026 industry standards.What are SMD Resistors? (2026 Overview)SMD Resistor, also known as a Chip Resistor, is a surface-mount passive component essential for modern high-density electronics. Manufactured by sintering metal powder and glass glaze on a ceramic substrate, these components offer superior resistance to humidity, high temperatures, and vibration compared to legacy through-hole parts. As of 2026, they are the industry standard for everything from AI hardware to smartphones. While different resistors feature varied specifications, the critical question remains: how are these microscopic resistance values marked and decoded? Figure 1. Structure of SMD ResistorsⅠ How to Read Resistor Markings: 4 Key MethodsTo master resistor identification, one must understand the four global standards used to denote resistance values. These methods are governed by IEC 60062 standards:1. Direct Marking MethodThis method prints the actual numbers and unit symbols directly on the resistor surface. The allowable error (tolerance) is expressed as a percentage. If no deviation is marked, the standard tolerance is typically ±20%.2. Text Symbol MethodThis approach uses a combination of Arabic numerals and text symbols to indicate the nominal resistance and tolerance. The number preceding the symbol represents the integer value, while the number following represents the decimal. Tolerance characters are standardized: D (±0.5%), F (±1%), G (±2%), J (±5%), K (±10%), M (±20%).3. Digital Method (Most Common for SMD)This method uses a 3-digit or 4-digit code. Read from left to right, the initial digits represent the significant figures (effective values), and the final digit is the exponent (multiplier), indicating the number of zeros to add. The unit is always Ohms (Ω).4. Color Code Marking MethodWhile rare on modern SMDs (except MELF packages), color bands are the standard for through-hole resistors. The bands represent values and multipliers:Black (0), Brown (1), Red (2), Orange (3), Yellow (4)Green (5), Blue (6), Violet (7), Gray (8), White (9)Tolerance: Gold (±5%), Silver (±10%), Colorless (±20%)Figure 2. Universal Resistor Color Code DiagramReading Tip: For a four-band resistor, the last band (usually gold/silver) is the tolerance. The first two bands are digits, and the third is the multiplier. For five-band precision resistors, the first three are digits, the fourth is the multiplier, and the fifth is the tolerance. Ⅱ Calculating SMD Resistor Values (Step-by-Step)2.1 Understanding Character Code MarkingsVideo: SMD Resistor Coding ExplainedMarking chip resistors requires a compact system due to the component's microscopic size. While large packages may use full numbers, 0603, 0805, and 1206 packages use coded systems. Here is the 2026 standard breakdown for decoding these values:The 3-Digit System (Standard Tolerance ±5%):1. The first and second digits represent the significant resistance figures.2. The third digit is the multiplier (10^x).Decoding Guide by Third Digit:• Ends in 0: No extra zeros. Example: 100 = 10 Ω.• Ends in 1: Add one zero (x10). Example: 101 = 100 Ω.• Ends in 2: Add two zeros (x100). Example: 102 = 1,000 Ω (1 kΩ).• Ends in 3: Add three zeros (x1,000). Example: 103 = 10,000 Ω (10 kΩ).• Ends in 4: Add four zeros. Example: 104 = 100 kΩ.• Ends in 5: Add five zeros. Example: 105 = 1 MΩ.• Ends in 6: Add six zeros. Example: 106 = 10 MΩ.The 4-Digit System (Precision Tolerance ±1%):For higher precision, three significant digits are used. Example: 1001 means 100 + one zero = 1000 Ω (1 kΩ).Note: Ultra-small packages like 01005, 0201, and 0402 are physically too small for markings. These must be measured with a multimeter or tracked via reel tape labeling.2.2 Real-World Calculation ExamplesCase 1: 3-Digit Code (±5% Tolerance)This uses two significant digits followed by a multiplier.Calculation: 153 → 15 followed by 3 zeros → 15,000 Ω = 15 kΩDecimal Values: "R" represents the decimal point. Code 6R8 → 6.8 ΩCase 2: 4-Digit Code (±1% Tolerance)Common on packages like 0805, 1206, and 2512. The first three digits are significant.Calculation: 2372 → 237 followed by 2 zeros → 23,700 Ω = 23.7 kΩDecimal Values: 3R24 → 3.24 ΩCase 3: EIA-96 System (The "Cryptic" Code)Used for 1% tolerance resistors on small 0603 packages where 4 digits won't fit. This system uses a two-digit code (referencing a lookup table) and a letter multiplier.Format: [Code] [Letter]Example Multipliers: Y=0.01, X=0.1, A=1, B=10, C=100, D=1000, E=10000.E-96 Series Standard Resistance Lookup Table (Partial)ValueCodeValueCodeValueCode100011471721533102021501822134105031541922635107041582023236110051622123737113061652224338115071692324939118081742425540121091782526141124101822626742127111872727443130121912828044133131962928745137142003029446140152053130147143162103230948 ValueCodeValueCodeValueCode316494646568181324504756669882332514876771583340524996873284348535116975085357545237076886365555367178787374565497280688383575627382589392585767484590402595907586681412606047688792422616197790993432626347893194442636497995395453646658097696EIA-96 Calculation Examples:Code 29B: Lookup "29" in table → Value 196.Multiplier "B" → x10.Result: 196 × 10 = 1.96 kΩCode 10X: Lookup "10" in table → Value 124.Multiplier "X" → x0.1.Result: 124 × 0.1 = 12.4 ΩCase 4: The Underlined Code (Special 0603 Case)Sometimes you see a standard 3-digit code with a line under it on an 0603 package. This usually indicates the manufacturer uses the E-24 series values (loose tolerance) rather than E-96, but the calculation is standard.122 = 12 × 100 = 1.2 kΩ680 = 68 × 1 = 68 Ω (Note: 680 does not mean 680 ohms here, it means 68 and zero extra zeros). Ⅲ How to Identify Damaged SMD Resistor Values?When a resistor is burned or the marking is unreadable, use these four forensic engineering methods to deduce the value:1. Parallel Circuit ComparisonPCB designs, especially in power supplies and audio amplifiers, often use symmetrical channels. • Example: In an LCD backlight driver, if the resistor in Channel A is burnt, check the corresponding position in Channel B. Often R17 = R51, or R23 = R48. Measure the intact sibling component to find the value.2. Circuit Context Analysis (Pull-Up/Pull-Down)For Microcontroller (MCU) circuits, resistors connected to GPIO pins are typically "pull-up" or "pull-down" resistors used to stabilize logic levels.• Common Values: 3.3kΩ, 4.7kΩ, 10kΩ.• Deduction: If the resistor connects a data line to VCC or GND, replacing it with a 10kΩ resistor is a safe starting point for testing.3. Reference Similar SchematicsIf the exact schematic is unavailable, search for schematics of devices using the same main IC. Manufacturers often use the "Reference Design" provided by the chipmaker, meaning the peripheral resistor values will be identical across different brands.4. The Potentiometer Test (Advanced)If all else fails, trace the circuit diagram. Temporarily solder a high-value potentiometer (variable resistor) in place of the damaged part. Power on the device and slowly adjust the resistance while monitoring voltage levels until the circuit functions correctly. Remove the potentiometer, measure its set resistance, and replace it with the closest standard fixed resistor.  Ⅳ Top SMD Resistor Manufacturers (2026 Updated)Reliability is paramount in 2026 electronics. The following brands are currently recognized as Tier-1 manufacturers for automotive, industrial, and consumer electronics:YAGEO: Global leader in chip resistors (acquired KEMET).Vishay: Known for high-precision, military-grade foil resistors.Panasonic: Industry standard for high-reliability automotive parts.KOA Speer: Major supplier for automotive and industrial markets.Bourns: Famous for circuit protection and resistors.TE Connectivity: Specialist in harsh environment resistors.Other Notable Brands: ROHM, Ohmite, Welwyn, TT Electronics, UNI-ROYAL (Uniohm). ⅴ Frequently Asked Questions (FAQ)1. What is an SMD resistor used for?SMD (Surface Mount Device) resistors limit current, divide voltage, and stabilize signal lines in compact electronic circuits. They are essential for miniaturizing devices like smartphones, wearables, and IoT sensors where traditional through-hole components would be too bulky. 2. How do I calculate the value of a 3-digit SMD resistor?Use the formula: [1st Digit][2nd Digit] x 10^[3rd Digit]. For example, "103" means 10 x 10^3 (1000) = 10,000 Ohms or 10kΩ. 3. What does "R" mean in a resistor code like 4R7?The letter "R" represents the decimal point. It is used when the resistance value is too small to use a multiplier code. Therefore, 4R7 equals 4.7 Ohms. 4. What is the difference between 103 and 1002 markings?Both equal 10kΩ, but the marking indicates tolerance. "103" (3-digit) typically indicates ±5% tolerance. "1002" (4-digit) indicates higher precision, typically ±1% tolerance. 5. How do I read the cryptic "01A" or "29B" codes?These are EIA-96 codes for 1% precision resistors on small 0603 parts. You cannot read them directly; you must use an EIA-96 lookup table. The number refers to a value code, and the letter is the multiplier. 6. Why do some SMD resistors have no markings?Resistors in package sizes 0402, 0201, and 01005 are physically too small to print legible text. To identify these, you must measure them with a multimeter or refer to the manufacturer's reel tape packaging. 7. What does SMD stand for?SMD stands for Surface Mounted Device. It refers to the component itself. SMT (Surface Mount Technology) refers to the manufacturing process of placing these components onto a PCB. 8. What materials are SMD resistors made of?Most SMD resistors are "Thick Film" or "Thin Film" types. They consist of a ceramic substrate (alumina) coated with a resistive paste (metal oxides and glass). This is fired in a kiln, laser-trimmed to the exact value, and then coated with a protective layer.{ "@context": "https://schema.org", "@type": "Article", "mainEntityOfPage": { "@type": "WebPage", "@id": "https://www.kynix.com/Blog/How-to-Read-the-Value-of-SMD-Resistor-Example-Explained.html" }, "headline": "How to Read SMD Resistor Codes: The 2026 Guide to 3-Digit, 4-Digit & EIA-96 Markings", "image": "https://www.kynix.com/editor_u/image/20211027/2021102711243403.jpg", "author": { "@type": "Organization", "name": "Kynix Electronics" }, "publisher": { "@type": "Organization", "name": "Kynix Electronics", "logo": { "@type": "ImageObject", "url": "https://www.kynix.com/logo.png" } }, "datePublished": "2021-10-27", "dateModified": "2026-01-08", "description": "Learn how to calculate SMD resistor values using 3-digit, 4-digit, and EIA-96 codes. Includes updated 2026 lookup tables and troubleshooting steps for damaged components.", "articleBody": "SMD Resistor, called Chip Resistor, is one type of resistors..."}{ "@context": "https://schema.org", "@type": "FAQPage", "mainEntity": [{ "@type": "Question", "name": "What is an SMD resistor used for?", "acceptedAnswer": { "@type": "Answer", "text": "SMD (Surface Mount Device) resistors limit current, divide voltage, and stabilize signal lines in compact electronic circuits like smartphones and IoT devices." } }, { "@type": "Question", "name": "How do I calculate the value of a 3-digit SMD resistor?", "acceptedAnswer": { "@type": "Answer", "text": "Use the formula: [1st Digit][2nd Digit] x 10^[3rd Digit]. For example, 103 means 10 x 1000 = 10,000 Ohms (10kΩ)." } }, { "@type": "Question", "name": "What does 'R' mean in a resistor code like 4R7?", "acceptedAnswer": { "@type": "Answer", "text": "The letter 'R' acts as a decimal point. 4R7 represents 4.7 Ohms." } }, { "@type": "Question", "name": "How do I read EIA-96 codes like 01A?", "acceptedAnswer": { "@type": "Answer", "text": "EIA-96 codes require a lookup table. The number represents a significant value, and the letter represents a multiplier. For '01A', 01 is 100 and A is x1, resulting in 100 Ohms." } }]}{ "@context": "https://schema.org", "@type": "HowTo", "name": "How to Read a 3-Digit SMD Resistor Code", "description": "Step-by-step guide to calculating resistance from standard 3-digit markings found on most chip resistors.", "step": [{ "@type": "HowToStep", "name": "Identify the Significant Digits", "text": "Read the first two numbers on the resistor. These are your significant digits (e.g., in '103', the significant digits are '10')." }, { "@type": "HowToStep", "name": "Identify the Multiplier", "text": "Read the third number. This indicates the power of 10 to multiply by (or how many zeros to add). In '103', the multiplier is 3 (10^3 or 1000)." }, { "@type": "HowToStep", "name": "Calculate the Result", "text": "Multiply the significant digits by the multiplier. 10 x 1000 = 10,000 Ohms (10kΩ)." }]}

Introduction As a passive device, Capacitors have unique functions in electronic circuits such as tuning, bypassing, coupling, and filtering. For example, it is used in the tuning circuit of the transistor radio, and also used in the coupling circuit and bypass circuit of the color TV. With the rapid development of electronic information technology, the update speed of digital electronic products is getting faster and faster. Capacitors play an important role in consumer electronic products such as flat-panel TVs (LCD and PDP), notebook computers, digital cameras and other products. Therefore, it is very important to ensure the capacitances and test its quality. Here this article will talk about how to test/check a capacitor in detail. 3 Ways to Check Capacitors in Circuit with Meters & Testers Catalog Introduction Ⅰ Test a Capacitor Using Multimeter 1.1 Digital Multimeter Use 1.2 Capacitor Measurements Matter 1.3 Test Non-polar Capacitors 1.4 Test Polar Capacitors 1.5 Test Chip Capacitors 1.6 Test Solid State Capacitors 1.7 Test Electrolytic Capacitors 1.8 Test Variable Capacitors 1.9 Capacitor Polarity Distinction Ⅱ Test a Capacitor Using Bridge Ⅲ Test a Capacitor Using Professional Equipment Ⅳ FAQ Ⅰ Test a Capacitor Using Multimeter 1.1 Digital Multimeter Use 1.1.1 Using Capacitance GearSome digital multimeters have the function of measuring capacitance, and their ranges include five ranges: 2000p, 20n, 200n, 2μ and 20μ. During test, the two pins of the discharged capacitor can be directly inserted into the Cx jack on the meter board, and the display data can be read after selecting the appropriate range.🔺2000p range is suitable for measuring capacitances less than 2000pF.🔺20n range is suitable for measuring capacitances between 2000pF and 20nF.🔺200n range is suitable for measuring capacitances between 20nF and 200nF.🔺2μ range is suitable for measuring capacitances between 200nF and 2μF.🔺20μ gear is suitable for measuring the capacitance between 2μF and 20μF. Experiments have proved that some types of digital multimeters have large errors when measuring small capacitors below 50pF, and there is almost no reference value for measuring capacitors below 20pF. At this time, the series method can be used to measure small-value capacitors. For example: measure a capacitor of about 220pF. Test its actual capacity C1 with a digital multimeter, and then connect the small capacitor in parallel to measure its total capacity C2, then the difference between the two (C1-C2) is the capacity of the small capacitor. It is very accurate to use this method to measure small capacitance of 1-20pF. 1.1.2 Using Resistance GearIn practice, it has proved that the charging process of the capacitor can also be observed with a digital multimeter, which is actually a discrete digital quantity that reflects the change of the charging voltage. Assuming that the measurement rate of the digital multimeter is n times/second, in the process of observing the charging of the capacitor, n independent and successively increasing readings can be seen every second. According to this display values, the quality of the capacitor can be detected and the size of the capacitance can be estimated. This method is suitable for measuring large-capacity capacitors from 0.1μF to several thousand microfarads. 1.1.3 Using Voltage GearUsing a digital multimeter to detect capacitors with DC voltage is actually an indirect method. This method can measure small-capacity capacitors from 220pF to 1μF, and can accurately measure the size of the capacitor's leakage current. 1.1.4 Using BuzzerUsing the buzzer of the digital multimeter, you can quickly check the quality of the electrolytic capacitor. For example, set the digital multimeter to the buzzer position, and use two test leads to contact the two pins of the capacitor Cx to be tested. A short buzzer should be heard, then the sound stops, and the overflow symbol "1" is displayed at the same time. Then, exchange the two test leads for another measurement, the buzzer should sound again, and finally the overflow symbol "1" is displayed. This situation indicates that the measured electrolytic capacitor is basically normal. At this point, you can dial to 20MΩ or 200MΩ to measure the leakage resistance of the capacitor to judge whether it is good or bad. Figure 1. Various Capacitor Stuff 1.2 Capacitor Measurements Matter (1) Before the measurement, the two pins of the capacitor should be short-circuited and discharged, otherwise the reading process may not be observed.(2) Do not touch the capacitor electrode with two hands during the measurement process, so as to prevent the meter from jumping.(3) During the measurement process, the value of Vin(t) changes exponentially, and it drops quickly at the beginning. As time goes by, the speed of decline will become slower and slower. When the capacity of the capacitor Cx under test is less than several thousand picofarads, and the measurement rate of the meter is low, it is too late to reflect the initial voltage value, so the initial display value of the meter is lower than the battery voltage at very first.(4) When the measured capacitance value is greater than 1μF, in order to shorten the test time, the resistance gear can be used. In addition, when the capacity of the capacitor under test is less than 200pF, it is difficult to observe the charging process because the change in readings is very short.Be sure to cut off the power and discharge capacitor before measuring. The method of discharging is to find a metal object such as a screwdriver, hold the exposed part of the metal on the insulating handle with the two pins, and measure the capacitance with a digital multimeter. Locate the capacitor block and then plug the two pins into the socket for capacitance measurement, and wait for the changing reading on the meter screen to stabilize. The actual value is the capacitance of the capacitor on the side. If has leakage, an analog multimeter can be used. When measuring, the small-capacity capacitor multimeter can be placed in RX1K or RX100. The two test leads are connected to the capacitor, the pointer deflects clockwise, and then as the capacitor is fully charged, there is no current flows, finally the watch hand will reappear counterclockwise and return to infinity. The larger the angle of the watch hand, the greater the capacity. During the deflection process, the pointer must swing at a constant speed so that it can return to infinity, which preliminarily shows that the capacitor has no leakage.If the needle suddenly slows down or does not return at a certain position on the dial, it means that the capacitor is leaking in a certain period. If it is displayed as infinity at the end, it shows that there is no leakage, but this can only be a rough judgment. If you want to find an accurate value, you have to use a capacitance meter. And the observation characteristic on the capacitance leakage tester or oscilloscope, this is impossible for ordinary people to have. There are also capacitors that have withstand voltage, which is generally written on their body. However, some ceramic capacitors are not marked on it, be careful when selecting them. Figure 2. Film Capacitor (cbb21) 1.3 Test Non-polar CapacitorsIf it is a non-polar capacitor, the multimeter can be adjusted to the "diode" gear to measure the on-off state. If the multimeter displays "1", it is normal; if displays "0" or other numbers, it means the capacitor is damaged. 1.4 Test Polar CapacitorsElectrolytic capacitors with polarities have "bulging", "deformation" or "leakage" in the shell, which show they are damaged. The capacitance block of a digital multimeter can also be used to measure the quality of the capacitor:(1) According to the rated capacitance marked by the capacitor, set the multimeter to the appropriate block.(2) Insert the capacitor into the hole of the multimeter to measure the capacity.If the capacitance is within the rated value range, it means the capacitor is intact, otherwise the capacitor is damaged. 1.5 Test Chip Capacitors1) Adjust the multimeter to the appropriate ohm gear. The principle of gear selection is: 1μF capacitor uses 20K gear, 1~100μF capacitor uses 2K gear, and larger than 100μF uses 200 gear.2) Determine the polarity. First adjust the multimeter to 100 or 1K ohms. Assuming that one pole is positive, connect the black test lead to it, and the red test lead to the other pole. Note the resistance value, and then discharge the capacitor. Then change the test lead to measure the resistance. The black test lead with a large resistance value is connected to the positive electrode of the capacitor.3) Then connect the red pen of the multimeter to the positive electrode of the capacitor, and the black pen to the negative electrode of the capacitor. If the display gradually increases from 0, and the overflow symbol 1 is displayed at the end, which shows the capacitor is normal. If it is always displayed as 0, the capacitor is short-circuited. If 1 is displayed, the internal circuit of the capacitor is open. Figure 3. Chip Capacitors 1.6 Test Solid State Capacitors✔️Capacitance Greater than 20μFWith a common digital multimeter, the maximum measured value of the capacitance block is 20μF, which sometimes cannot meet the test requirements. To this end, the following simple method can be used to measure capacitance greater than 20μF, and also the maximum capacitance of several thousand microfarads can be measured. When using this method to measure large-capacity capacitors, there is no need to make any changes to the original circuit of the digital multimeter.The measurement principle of this method is based on the formula C = C1C2/(C1+C2) in series with two capacitors. Since two capacitors with different capacities are connected in series, the total capacity after series connection is smaller than the smaller capacitor. Therefore, if the capacity of the capacitor under test exceeds 20μF, only one capacitor with a capacity less than 20μF should be used. In series with it, it can be directly measured on the digital multimeter. According to the formula above mentioned, it is easy to deduce C1=C2C/(C2-C), using this formula can calculate the capacitance value of the capacitor under test. ✔️Capacitance Less than 10μFBecause the capacity of a fixed capacitor below 10pF is too small, it can only be roughly checked for leakage, internal short circuit or voltage breakdown with a multimeter. When measuring, you can choose the R×10k block, and use two test pens to connect the two pins of the capacitor arbitrarily, and the resistance should be infinite. If the measured resistance value (the pointer swings to the right) is zero, it means that the capacitor is damaged by leakage or has internal breakdown. ✔️Capacitance between 10PF and 0.01μFDetect whether the capacitor is charging, and then judge whether it is good or bad. The multimeter selects the R×1k block. The β value of the two transistors is above 100, and the penetration current should be small. A composite tube can be used consist of silicon transistors. The red and black test leads of the multimeter are respectively connected to the emitter e and collector c of the composite tube. Due to the amplification effect of the composite triode, the charge and discharge process of the capacitor under test is amplified, and the amplitude of the pointer of the multimeter is enlarged, which is convenient for observation. It should be noted that during the test operation, especially when measuring small-capacity capacitors, it is necessary to repeatedly exchange the contact points A and B of the tested capacitor pin to clearly see the swing of the meter pointer. ✔️Fixed Capacitance of 0.01μFFor a fixed capacitance above 0.01μF, the R×10k block of a multimeter can be used to directly test whether the capacitor has the charging process and internal short circuit or leakage, in addition, the capacitance of the capacitor can be estimated according to the magnitude of the pointer swing to the right. Figure 4. Electrolytic Capacitors 1.7 Test Electrolytic Capacitors1) Because the capacity of electrolytic capacitors is much larger than that of general fixed capacitors, ranges should be selected for different capacities when measuring. According to experience, in general, the capacitance between 1 and 47μF can be measured with the R×1k block, and the capacitance larger than 47μF can be measured with the R×100 block.2) Connect the red test lead of the multimeter to the negative pole and the black test lead to the positive pole. At the moment of contact, the pointer of the multimeter will deflect to the right by a greater degree (for the same electrical barrier, the greater the capacity, the greater the swing), and then gradually turn to the left Turn around until it stops at a certain position. The resistance value at this time is the forward leakage resistance of the electrolytic capacitor, which is slightly larger than the reverse leakage resistance. Practical experience shows that the leakage resistance of electrolytic capacitors should generally be more than several hundred kΩ, otherwise, it will not work normally. In the test, if there is no charging phenomenon in the forward and reverse directions, that is, the hand does not move, it means that the capacity has disappeared or the internal circuit is broken; if the measured resistance value is very small or zero, it means that the capacitor has a large leakage or has been broken down.3) For electrolytic capacitors with unknown positive and negative signs, the above method of measuring leakage resistance can be used to distinguish. That is to measure the leakage resistance arbitrarily, remember its size, and then exchange the test leads to measure a resistance value. The larger resistance of the two measurements is the positive connection, that is, the black test lead is connected to the positive electrode, and the red test lead is connected to the negative electrode. Use a multimeter to block electricity and charge the electrolytic capacitor. According to the magnitude of the pointer swing to the right, the capacity of the electrolytic capacitor can be estimated.When measuring electrolytic capacitors, if the measured value does not change significantly, the corresponding pins of the probe should be exchanged for multiple measurements. 1.8 Test Variable Capacitors1) Rotate the shaft gently and smoothly. When pushing the load shaft in full directions, there should be no looseness of it.2) Rotate the shaft with one hand and gently touch the outer edge of the film set with the other hand. You should not feel any looseness. The variable capacitor with poor contact between the rotating shaft and the moving plate can no longer be used.3) Place the multimeter in the R×10k gear, connect the two test leads to the moving piece and the lead end of the fixed piece of the variable capacitor with one hand, and slowly rotate the shaft several times back and forth with the other hand. The pointers of the multimeter should not move at infinity. In the process of rotating the shaft, if the pointer sometimes points to zero, it indicates that there is a short-circuit point between the moving piece and the fixed piece. If it encounters a certain angle, the multimeter reading is not infinity but a certain resistance value, indicating that the variable capacitor has a leakage phenomenon between the film and the stator. 1.9 Capacitor Polarity DistinctionThe black part with a mark on the capacitor is negative. There are two semicircles on the position of the capacitor on the PCB, and the pin corresponding to the colored semicircle is the negative electrode. The length of the pins is also useful to distinguish the polarity: the long pin is anode and the short pin is cathode.When we don't know the positive and negative poles of the capacitor, we can use a multimeter to figure them out. The medium between the two poles of the capacitor is not an absolute insulator, and its resistance is not infinite, but a finite value, generally above 1000 megohms. The resistance between the two poles of a capacitor is called insulation resistance or leakage resistance. Only when the positive electrode of the electrolytic capacitor is connected to the positive power supply (the black test lead), and the negative terminal is connected to the negative power supply (the red test lead), the leakage current is small (the leakage resistance is large), on the contrary, the leakage current increases (the leakage resistance decreases).Without knowing it, you can first assume the “+” pole of a certain pole. Using R*100 or R*1K of the multimeter, connect the test leads, and record the scale of the stop of the test needle (the resistance value of the test needle to the left is large), and the reading can be read directly for a digital multimeter. Then discharge the capacitor, then exchange the two test leads, and perform the measurement again. In the two measurements, the black test lead is connected to the positive electrode of the electrolytic capacitor when the last position of the needle is to the left (or the end with large resistance).When measuring large capacity capacitors, if you need to measure the positive and negative back and forth, discharge it to avoid damage to the multimeter. In addition, in high-frequency circuits, switching power supply circuits have many small capacitors, which ordinary multimeters cannot correctly judge whether they are good or bad. In terms of this case, it is recommended to use a dedicated digital capacitance meter to measure. Figure 5. SMD Capacitor Ⅱ Test a Capacitor Using BridgeThe data measured with a multimeter is not too accurate, and it can only measure the deviation of the capacity. For a little professional, you can use a bridge. When testing a capacitor with a digital bridge, you can clamp the lead of the capacitor to test its capacity, which can also show the loss of the capacitor, especially through the loss, it is easier to distinguish the quality of the capacitor.   Ⅲ Test a Capacitor Using Professional EquipmentIn general, capacitors have special test equipment for each performance, such as capacitor durability test, destructive test, loss angle test, inter-electrode withstand voltage test, self-healing test, charge and discharge test, pulse voltage test, spontaneous combustion test, ripple current durability test, etc., but for most users, these devices are more expensive and difficult to operate. If you really want these data, you can entrust a third party to test or ask the manufacturer for relevant information.   Ⅳ FAQ1. How do you check if a capacitor is bad?Use the multimeter and read the voltage on the capacitor leads. The voltage should read near 9 volts. The voltage will discharge rapidly to 0V because the capacitor is discharging through the multimeter. If the capacitor will not retain that voltage, it is defective and should be replaced.   2. How do you tell if a capacitor is bad with a multimeter?If the capacitance value is within the measurement range, the multimeter will display the capacitor's value. It will display OL if a) the capacitance value is higher than the measurement range or b) the capacitor is faulty.   3. What are the symptoms of a bad start capacitor?Start Capacitor FailureMotor run capacitor failure symptoms include warm air flowing from the vents inside the home, the air conditioner taking more time than usual to kick on or it turns off before it is programmed to, or there is a constant low hum emitting from the machine that isn't typical.   4. Can a capacitor test good and still be bad?It can, and most often does, although it is probably lower in capacitance than it originally was, but still usually within tolerance. There isn't likely to be a problem with leakage. There are two ways to test an ESR meter, a circuit unpowered or an oscilloscope.   5. How long can a capacitor last?Age. Like all things, capacitors have a limited life span. Most are designed to last approximately 20 years, but a number of factors can cause them to wear out more quickly.   6. How do you identify a capacitor?Ceramic types of capacitors generally have a 3-digit code printed onto their body to identify their capacitance value in pico-farads. Generally the first two digits indicate the capacitors value and the third digit indicates the number of zero's to be added.   7. Will a capacitor discharge on its own?Will a Capacitor Discharge On Its Own? In theory, a capacitor will gradually lose its charge. A fully charged capacitor in an ideal condition, when disconnected, discharges to 63% of its voltage after a single time constant. Thus, this capacitor will discharge up to near 0% after 5 time constants.   8. How do I know if my AC capacitor is bad?The most common signs and symptoms of a bad AC capacitor include:AC not blowing cold air.AC takes a while to start once you turn it on.Humming sound coming from your air conditioner.AC shuts off on its own.AC won't turn on.   9. What side of capacitor is positive?To tell which side is which, look for a large stripe or a minus sign (or both) on one side of the capacitor. The lead closest to that stripe or minus sign is the negative lead, and the other lead (which is unlabeled) is the positive lead.   10. Can I use a multimeter to discharge a capacitor?The multimeter isn't used directly to discharge the stored energy of a capacitor. Instead, people use it to measure the voltage and power of the capacitor to know whether it is fully released or not. You can use different tools such as a light bulb or a DIY discharge tool for the process.   11. How fast can a capacitor discharge?A fully charged capacitor discharges to 63% of its voltage after one time period. After 5 time periods, a capacitor discharges up to near 0% of all the voltage that it once had.   12. Can a bad capacitor ruin a compressor?Using the wrong capacitor rating or a poor quality capacitor can adversely affect the operation of the motor, the compressor or an entire HVAC system. ... Depending on the motor load, this may result in a reduction in the motor's overall speed.   13. Can I replace a start capacitor with a run capacitor?Run Capacitors. Start capacitors give a large capacitance value necessary for motor starting for a very short period of time (usually seconds long). ... A start capacitor can never be used as a run capacitor, because it cannot not handle current continuously.   14. How do you check a capacitor without a multimeter?Just connect those two ends of the capacitor to a single phase supply and switch it ON for a few seconds. Then take that two terminal and short it, you will get a spark. And so you can somewhat assume that your capacitor is in good condition.   15. What if a capacitor reads high?The high resistance across the capacitor is a sign that the capacitor is faulty. It is reading as if there is an open circuit.   16. How many ohms should a capacitor have?Make sure the capacitor is fully discharged. Set the meter on the Ohmic range (Set it at least on 1000 Ohm = 1kΩ). Connect the multimeter probes to the capacitor terminals (Negative to Negative and Positive to Positive).   17. What if a capacitor reads low?If it reads lower than nominal value, you may want to replace it. Non-polar capacitors lower than 1μF should not alter that much with aging. Capacitors in frequency sensitive circuits such as filters, time delays, should have a tighter tolerance.   18. What happens when capacitor goes bad?A bad capacitor prevents the exterior unit from properly functioning, which hinders the cooling process as a whole. Second, improper voltage delivery to exterior unit components forces the system to work harder as it attempts to perform its job. Additional components often sustain damage due to a faulty capacitor.   19. How can you tell if a capacitor is bad?Symptoms of defective capacitors may include:Excessive noise in audio or video, including 60hz audio hum or rolling bars in video.Scratchy, distorted, or missing audio.Low contrast, blurry, or distorted LCD displays.Intermittent or outright failure.   20. What does a damaged capacitor look like?A busted capacitor can be obviously broken (leaking brownish fluid, corroded, or with the leads severed), but sometimes it's subtle. The top of a blown capacitor will be slightly bent outwards in a convex shape, rather than flat or slightly indented inwards like a working capacitor.