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Warm hints: The word in this article is about 3000 words and reading time is about 15 minutesSummaryThis article is mainly about space monitoring and location technology of AR&VR equipment. All AR&VR products must have accurate spatial monitoring and positioning capabilities in order to achieve a full range of head， hand interactions in order to provide users with a more realistic virtual experience. CoreResearch on space monitoring and location technology of AR&VR equipmentPurposeIntroduce space monitoring and location technology of AR&VR equipmentProductAR&VR EquipmentCategoryElectronic productsApplicationsAR&VR technologyTechnologyInside-out space monitoring and positioning and outside-in space monitoring and positioning     Catalogs CatalogsI、Current Status of AR&VR ProductsV、 PC VRII、Cardboard productsVI、Space positioning technology categoryIII、Head motion controlled all-in-one            machine1. Inside-out space monitoring and positioning technologyIV、 AIO machine with space monitoring and positioning2. Outside-in space monitoring and positioning technology  Introduction I、Current Status of AR&VR ProductsThere are many AR&VR products already on the market. The price varies from Cardboards to Hololens, and the user experience varies greatly. First of all, VR products can be divided into the following categories: cardboard products, one-touch control integrated machine, AIO machine with space monitoring and positioning, PC VR.  DetailII、Cardboard productsCardboard productsThis kind of product is the simplest VR product. It comes from Google's carton VR box. Simply, it uses two convex lenses to project the contents of the mobile phone into screens. It uses the IMU inside the phone to judge the user's head movement to adjust the movement direction of the VR display content. This kind of product began to ship a large number of domestic white cards in 2015, but the overall effect of VR depends on the configuration of the mobile phone and the quality of the optical lens. It is only an entry-level VR experience product.The first generation VR products of game companies and some domestic video content are basically in this form. The most representative is the Storm Box, with a BT control handle for menu selection. The emergence of this type of product has indeed played a big role in the promotion of the entire VR industry, but its drawbacks are also very obvious. The Cardboard-style VR device ushered in a particularly big opportunity in 2016, that is, Google proposed Daydream VR. Google wants to enhance the VR Cardboard users’ experience, and hopes to be able to dominate the entire VR ecosystem in 2016. The Daydream mobile phone Pixel, Pixel XL and Daydream Viewer wearing the Cardboard were released in the year, and also equipped with a built-in IMU remote control handle. According to Google's requirements for VR device user experience, it must reach a mobile phone with a certain hardware configuration, and with Daydream Viewer running related VR applications, so that users will not be dizzy. Since 2016, with the launch of products such as Huawei P9 and Lenovo MotoZ, there are more and more mobile phones supporting Daydream. It is expected that, in 2017, these products will completely break the stalemate of the poor Cardboard user experience.III、Head motion controlled all-in-one machineAll-in-one machineAIO machine, as its name, is a VR device that does not need to be inserted into a mobile phone or connected to a PC. Currently, there are representative DaPeng, Xiaoniao, KanKan, etc. Most of the products are listed in 2016. The features of these products are basically the same use of 1080p or 2K resolution display screens (some of which also use 2Kx2 dual screens) with specially designed FIN products designed for VR products aspherical optical lens. The overall picture quality and distortion have improved a lot. However, these products have a common feature, that is, only a simple head control, can only sit or stand in place by shaking his head to achieve VR control, can not do the first hand interaction. In order to remedy this defect, there are currently some external accessories with spatial position detection (the built-in IMU handle, somatosensory backpack, spatial positioning light ball, etc.) to enhance the overall VR user experience.IV、 AIO machine with space monitoring and positioningAIO machine with space monitoring and positioningSpace monitoring and positioning are generally two ways, Inside-out and Outside-in. Inside-out senses the spatial information outside the device through the built-in sensor and performs related positioning. The Outside-in is just the opposite. It uses an external sensor to sense the position of the VR device and provides positioning information to the VR application. For the all-in-one machine, the current view has selected the Inside-out solution without exception, thus avoiding the need to install an external sensor in advance. The user can pick up the VR device at any time and anywhere. It is expected that some of the major products coming on the market in 2017, such as the second generation of the DaPeng AIO Machine and the Storm AIO Machine, will have space positioning capabilities, which will greatly enhance the VR user experience, especially VR games.V、 PC VRPC VRThe most representative products are the HTC Vive, Sony PSVR and HTC Oculus. After the three swordsmen went public in 2016, the HTC Vive has become a standard configuration for the VR experience room. Many other industry customizations are based on Vive. Sony PSVR has sold about 1 million units in less than half a year, which has greatly improved the overall level of user experience in the entire VR industry. The feature of these three products is the use of external space positioning technology. For example, Vive uses an external infrared laser transmitter, head and handle senses transmitter location to determine its position and trajectory. PSVR and Oculus use external sensors to sense the visible light or infrared light emitted by the headlights and the handle to determine the positions of the heads and the handles, so that the heads and the handles can accurately know their respective relative positions and trajectories in space at any time. This can make the application of VR more realistic.Next, let’s talk about AR products. At present, there is a big gap between AR products. Some AR glasses products only project virtual information, images, etc., and are not actually related to the actual environment where the user is located. Such products can only achieve 6DOF motion tracking by the projected virtual information following the head movement. But it is impossible to fuse the virtual object with the actual environment where the user is. For example, the famous ODG, the latest product only supports 6DOF motion tracking, there is no spatial positioning function.AR product ODGShanghai Zhishi's smart glasses also have similar functions to those of ODG, but their positioning is a live broadcast from the first point of view. Therefore, only relevant information and videos for shooting can be displayed in the glasses without spatial positioning. However, it is understood that they are also developing a built-in TOF depth camera glasses, which can achieve 6DOF + spatial positioning function.Shanghai Zhishi's smart glassesThe currently available AR products have the best space monitoring and positioning capabilities. The best match for virtual objects is the Lenovo Phab2 Pro based on Google's Tango space positioning technology and the Microsoft Hololens. Although these two products are very different in shape, they are essentially the full integration of 6DOF+SLAM, achieving spatial positioning and motion tracking. Their AR effects can basically be virtual objects and the actual environment. Convergence, no matter how the user moves or views from what angle, the feeling is just like the real object is in front of me. However, Hololens' accuracy and stability of 6DOF+SLAM are still higher than those of Tango in terms of the effect of actual use. This is closely related to the choice of hardware design platform, type and number of sensors, and core algorithms.Hololens ARIn addition, there are actually many companies in the country that are developing related AR products. Among them, the distinctive feature of Micro Eye's SMAKKEST is not only similar to Hololens, but also similar to Hololens in terms of function. The effect of 6DOF+SLAM is said to be recognized by Hololens.  AnalysisVI、Space positioning technology categorySpace monitoring and positioning technology, in fact, can be divided into two major categories initially, one is the Inside-out space monitoring and positioning, and the other is the Outside-in space monitoring and positioning.1. Inside-out space monitoring and positioning technologyInside-out space monitoring and positioning technology, technology is essentially similar to the process of human-to-environmentally-aware environment of the human eyewear. It senses the external space from the inside of the device and is therefore called the Inside-out positioning method. Inside-out space monitoring and positioning technology is also divided into two categories. One is the spatial monitoring and positioning based on SLAM technology. This is also a basic function required by the fiery robotics industry. SLAM is the English abbreviation for simultaneous localizatiion and mapping. It means that the device itself starts to move from an unknown location in an unknown environment, locates itself according to location estimates and maps during the movement, and builds incremental maps based on its own positioning to achieve autonomous detection and positioning navigation of the device itself. . At present, most AR products use Inside-out spatial location technology.The representative products of the space monitoring and positioning technology based on SLAM are Lenovo Phab2 Pro Tango mobile phone and Hololens. Both use depth monitoring + Fisheye and IMU fusion for sports monitoring. The difference is that the depth monitoring technology is different (Tango uses TOF, and Hololens uses structured light) and the number of Fisheye motion and feature point monitoring is different. Hololens' spatial positioning effect is more accurate and stable than Tango's, and Hololens' effect is in low light and glass light transmission. The current Tango victory, but Tango technology is not static, the next generation of Tango technology also supports multiple Fisheye camera.The Lenovo Phab2 Pro Tango phone uses a TOF depth camera, a 155-degree FOV Fisheye motion monitoring camera and an RGB camera, Fisheye motion monitoring camera with IMU data fusion, feature point matching, providing the device with a complete trajectory The monitoring, together with the cloud image information of the TOF depth camera, can plot the position of the device itself in space and the trajectory of the movement in real time. At the same time, through Tango's own zone learning function, when returning to the space that has already passed, once the Fisheye camera By detecting the stored feature points and matching them, it is possible to quickly perform spatial positioning. This is very important for AR equipment and it ensures that users can quickly use it anytime, anywhere. The working principle of Tango is not explained here. You can refer to Lin Shigong's another article for detailed understanding.The working principle of TangoThe Hololens design of Microsoft is very unique and very affluent. It has newly developed an HPU (Holographic Processing Unit) based on Intel's CPU and GPU technology. The device adopts the configuration of CPU+GPU+HPU. Like Tango, it does not need to External PCs look to achieve complete space monitoring and positioning. On the sensor side, depth monitoring uses two structured light cameras with four structured light-grating emitters for depth monitoring. In addition, there are two Fisheye cameras on the left and right of Hololens, so that more feature points in the space environment can be monitored. Hololens' space positioning accuracy and stability are therefore much higher than those of Tango.HPU（Holographic Processing Unit）The other type is based on the marker (pointer) space monitoring and positioning technology, simply put some like two-dimensional code, special color graphics patterns or light spots as markers in the actual space, equipment to monitor these markers The location of the point to determine their position and movement trends. The HTC Vive is a representative of this type. The following figure shows the working principle of spatial location of the HTC Vive.The working principle of spatial location of the HTC ViveVive emits laser light through two fixed laser emitters. Each base station has an infrared LED array. Two infrared laser emitters with rotating shafts perpendicular to each other are distributed. One is X-axis scanning, and the other is Y-axis scanning. The lasers have a fixed phase difference of 180 degrees. When one of the lasers emits an X-axis scan, the other laser emits a Y-axis scan.The HTC Vive has a shell that is densely covered with 32 light sensors, each oriented in different directions. These sensors are used to receive the infrared laser emitted by a fixed laser emitter. The computer connected to Vive controls all the devices to operate synchronously. The light sensor on the head reveals the time when the laser light reaches each sensor in the X-axis and Y-axis directions and the phase relationship between the two different laser emitters, and the phase difference of each light sensor can be calculated. Accurately locate the head position and trajectory.There are 24 light sensor on the Vive handle. The working principle and head of the handle are the same. It will not be repeated here.The HTC Vive ShellIn addition, it is necessary to mention that domestic Ximmerse, they also introduced a VR device for the Outside-in space positioning package design, through this space positioning package, can provide space-free VR devices with similar accuracy with the HTC Vive Space monitoring and positioning capabilities. The positioning package includes a dual camera module, two control handles with a light ball. When used, the dual camera module is externally mounted on the head display. The dual camera captures the light ball of the control handle to determine the position of the handle in the space, and the handle Through BT to transmit its 6DOF information to the module, the module fuses the 6DOF and the position information of the ball to achieve omni-directional positioning, thereby improving the interaction of the first hand. The advantage of this solution is that under any ambient lighting conditions, the positioning accuracy is not affected by the ambient light, and the positioning accuracy is high. However, this solution cannot monitor and locate the overall space environment in which the user is located. It can only monitor the spatial position information of the photo ball handle, but its advantage is that the original VR device without space positioning can have at least similar HTC Vive. Spatial positioning capabilities.Ximmerse2. Outside-in space monitoring and positioning technologyOutside-in space monitoring and positioning technology is currently the VR device is a relatively mature space positioning technology, Sony PSVR and Oculus are based on a similar program, but Oculus is in an external infrared camera plus point initiative marks the way to get Higher accuracy and faster response time. The PS VR directly uses the PS 3's MOVE system. The principle is similar to that of the Kinect. An external binocular depth camera is used for motion recognition and tracking. There is a light indication on the head, and a different color light ball is at the top of the handle. The external dual camera checks the trajectory of the headlight and the ball on the handle at any time. At the same time, the PS StaTIon receives the IMU information of the head display and handle returned by the BT. , Through the calculation you can get a complete headshot and handle movement trajectory and positioning in space.PS StaTIonFrom the principle and the effect of actual use, the space monitoring and positioning precision of HTC Vive is not high, although Sony's gaming and PSVR wearing wearing their own moderate than Vive better, but the spatial positioning accuracy is not high, it affects the VR The overall experience of the game. So we see from Sony's official website a new spatial orientation of Sony patent, this patent is to be ready for the next generation of PVSR, from the description of the patent point of view should be similar to HTC's fixed laser emitters way, with this program The current practice of PSVR is the opposite. Instead of using an external camera to take pictures (outside-in positioning), the external VR signal is used to locate the direction of the VR helmet in space. This can provide similar HTC Vive usage accuracy (probably higher), and can capture the user's various poses and trajectories 360 degrees without dead ends.Outside-In positioningOculus space monitoring and positioning technology with Sony PSVR similar difference is PSVR camera uses a dual monitor visible external program, and is an active Oculus uses infrared light to the head and the handle are placed significant infrared emitting LED , Through an external infrared camera for shooting and capturing the headlights and infrared light spot information on the handle, so as to obtain head trajectory and handle movement trajectory and spatial position information.Whether it is Sony PSRV or Oculus's Outside-in program, there is a problem, that is, the external camera is fixed, and when the user is back to the camera, the camera can not detect the head and the handle on the light, may There is a possibility of missed supervision, thus affecting the user experience, which does not exist on the HTC Vive.Another Marker point-based Outside-in space monitoring and positioning technology is Ximmerse's photosphere with dual-camera solution. This is contrary to their previously mentioned Inside-out solution, where dual camera monitors have been placed. Indoor fixed position, and then put the ball in the VR head and handle, head and handle during the movement of a dual camera monitor recorded head and handle in the space of the three-dimensional position and their movement data, through BT or WiFi is passed to VR heads to perform related operations and processing, and feedback is implemented on the screen to allow them to freely move around in the virtual environment and interact with things in the virtual world.Lightball + Dual Camera SolutionAnalog of Lightball + Dual Camera SolutionHere is a video about Augmented Reality vs Virtual Reality:Augmented Reality vs Virtual Reality - AR vs VR | The Future ! | Tamil Tech  Book RecommendationVirtual, Augmented, and Mixed Realities in EducationThis book describes the current state of the art of various types of immersive learning: in research, in practice, and in the marketplace. It discusses advanced approaches in the design and development for various forms of immersive learning environments, and also the emerging innovations in assessment and research in the field.--by Dejian Liu, Chris Dede, Ronghuai Huang, John Richards Experience on Demand: What Virtual Reality Is, How It Works, and What It Can DoVirtual reality is able to effectively blur the line between reality and illusion, pushing the limits of our imagination and granting us access to any experience imaginable. With well-crafted simulations, these experiences, which are so immersive that the brain believes they’re real, are already widely available with a VR headset and will only become more accessible and commonplace. But how does this new medium affect its users, and does it have a future beyond fantasy and escapism?--by Jeremy Bailenson  Relevant information about "Research on Space Monitoring and Location Technology of AR&VR Equipment"About the article " Research on Space Monitoring and Location Technology of AR&VR Equipment", If you have better ideas, don't hesitate to  write your thoughts in the following comment area. You also can find more articles about electronic semiconductor through Google search engine, or refer to the following related articles. 

Warm hints: The word in this article is about 5400 words and  reading time is about 25 minutes This article is equal to a comprehensive course about automobile sensors which including the basic introduction of automobile sensors, their types, applications, functions, and market analysis, etc.   Electronic technology has become the leading factor in the direction of the development of a new generation of automobiles, and sensors are the core components of electronic technology. More and more modern cars have used sensors more and more, in order to improve the economic, dynamic and emission performance of automobile engines, improve the braking performance, steering performance and safety performance of the vehicle. The key to achieve these goals lies in the electronic and intelligent vehicle, the prerequisite is the timely acquisition of all kinds of information, which is bound to require a large number of sensors in the car.   Catalogs I. An Overview of Automobile Sensors II. The Development History of Automobile Sensors III. Types of Automobile Sensors and Their Functions IV. Sensors Used in Automobile Engines and Their Functions 4.1 Automobile Temperature Sensor 4.2 Automobile Pressure Sensor 4.3 Air Flow Sensor 4.4 Fuel Flow Sensor 4.5 Engine Speed Sensor 4.6 Gas Concentration Sensor-oxygen Sensor V. Application of Vehicle Sensor in Vehicle Chassis Electronic Control   System VI. Sensor Application in Automobile Safety System VII. Other Major Automotive Sensors VIII. Automotive Sensors Market Size--Its Market Trend FAQ I. An Overview of Automobile Sensors   The automobile sensor is the input device of the automobile computer system. It takes all kinds of working condition information in the car, such as speed, temperature of various medium, engine operation condition and so on, and convert it into the device or device that can be input signal according to certain law. Simply speaking, the sensor transfers the non electric quantity to the electrical signal to transmit to the ECU, so that the car is in the best working state.     An Overview of Automobile Sensors In modern automotive electronic control, sensors are widely used in various systems of engine, chassis, and body. Automobile sensors are responsible for the acquisition and transmission of information in these systems. The information collected by the sensors is processed by the computer (electronic control unit), and the instructions sent to the actuator are formed to complete the electronic control. The sensor is a very important device in the electronic control and self-diagnosis system. It can identify the changes in the outside world and the changes of the system itself in time and then control the work of the system itself according to the information of the change. Each system control process relies on sensors to feedback information and achieves automatic control. Automotive sensors usually consist of three parts: sensing element, converting element, and measuring circuit.   （1）the sensitive element is the part that can be measured directly (or response), and is about to be converted into a non electric or other quantity that is determined to be determined by the sensing element of the sensor. （2）the conversion element converts the above non electric quantity into electrical parameters. （3）The function of the measurement circuit is to convert the electrical parameters input by the conversion element to the measurable quantity of voltage, current, or frequency, in order to display, record, control and handle the parts. Measurement circuit The sensor is at the interface between the research object and the test system, namely the first of detection and control. The sensor is a window to perceive, obtain and detect information. All the information obtained in the process of scientific research and automated production must be obtained by the sensor and converted into an easy transmission and processing electrical signal. Its role and status are particularly important. The following figure is the list of correspondence between the human body and machine, which helps us further understand its function.   In modern automotive electronic control, sensors are widely used in various systems of engine, chassis, and body. The vehicle sensors are responsible for the acquisition and transmission of information in these systems. The computer (electronic control unit ECU) sends out instructions to the actuator after the signal is processed in a hurry, and the electronic control is implemented. The sensor is a very important device in the electronic control and self-diagnosis system. It can identify the changes in the outside world and the changes of the system itself in time and then control the work of the system according to the information of the change. Each system control process relies on sensors to feedback information and achieves automatic control.     II. The Development History of Automobile Sensors   In the 1960s, there were only oil pressure sensors, oil sensors, and water temperature sensors on cars. They were connected with meters or indicator lights. After the 1970s, in order to control emissions, a number of sensors were added to help control the vehicle's power system, as the catalytic converters, electronic ignition, and fuel injection devices needed to maintain a certain air-fuel ratio to control emissions during the same period. Until the 1980s, ABS and airbags improved vehicle safety.   The Development History of Automobile Sensors Sensors are used today to determine the temperature and pressure of various fluids, such as intake temperature, air inlet pressure, cooling water temperature, and fuel injection pressure, and sensors used to determine the speed and position of various parts (such as speed, throttle opening, camshaft, crankshaft, angle and speed of the transmission, the position of the exhaust recirculation valve (EGR), etc.); and for measurement.   Sensors for engine load, detonation, broken fire, and oxygen content in exhaust gas; sensors to determine the seat position; sensors to determine wheel speed, road elevation difference, and tire pressure in the anti-lock braking system and suspension control device; and to protect the airbags of the front occupants, not only need more collision sensors and acceleration sensors.   The researchers also use the anti-collision sensors (ranging radar or other ranging sensors) to determine and control the lateral acceleration of the car, the instantaneous speed of each wheel and the required torque, so that the braking system is a part of the vehicle stability control system.   III. Types of Automobile Sensors and Their Functions   （1）According to the relationship of energy, sensors can be classified into two types: active and passive based on their energy relations. Most of the sensors used in cars belong to passive sensors, which require additional input power to produce electrical signals, so the sensor is actually an energy controller.    （2）According to the classification of signal conversion according to the signal conversion classification, it can be divided into one kind of non electricity conversion into another kind of non electricity, such as elastic sensitive element and pneumatic sensor; the other is the transducer converted from non electricity to electricity, such as thermocouple temperature sensor, piezoelectric accelerometer and so on.    （3）Classification according to input quantity according to input quantity is classified according to the measurement, which can be divided into displacement, velocity, acceleration, angular displacement, angular velocity, force, torque, pressure, vacuum degree, temperature, current, gas composition, concentration sensor and so on. For example, the following air flow sensor: Air flow sensor （4）According to the working principle classification according to the working principle of the sensor, there are resistance, capacitance, strain, inductance, photoelectric, photosensitive, piezoelectric, thermoelectric sensor, etc.   （5）According to the output signal classification, according to the sensor output signal, there are analog and digital sensors. Simulation system adoption and digital system adoption   IV. Sensors Used in Automobile Engines and Their Functions Electronic control of engines has been considered to be one of the main technology fields of automobiles. The sensor of engine control system is the core of the whole automobile sensor, and there are many kinds, including temperature sensor, pressure sensor, position and speed sensor, flow sensor, gas concentration sensor and detonation sensor, etc. These sensors provide the engine's work condition information to the engine's electronic control unit for accurate control of the engine working condition, in order to improve engine power, reduce fuel consumption, reduce exhaust emissions and perform fault detection. Sensors Used in Automatic Inductive Door   4.1 Automobile Temperature Sensor   Temperature sensor like automobile temperature sensor is mainly used to detect engine temperature, suction gas temperature, cooling water temperature, fuel temperature, and catalytic temperature. Water temperature state indicatior The temperature sensor has three main types: thermistor, wire wound resistor, and thermal couple resistor. These three types of sensors have their own characteristics, and their applications are also slightly different. The thermistor temperature sensor has high sensitivity and good response characteristics, but it has poor linearity and low temperature.   Among them, the universal temperature range is -50 C to 30 C, the precision is 1.5%, the response time is 10ms, the high-temperature type is 600 to 1000, the precision is 5%, the response time is 10ms; the precision of the wire-wound resistance temperature sensor is high, but the response characteristic is poor; the precision of the thermocouple resistance temperature sensor is high and the temperature range is wide, but it needs to be used together with the amplifier and cold end treatment.   Other practical products have ferric oxygen sensor (temperature range from -40 to 120, 2%), metal or semiconductor membrane air temperature sensor (temperature range from -40 to 150, 2%, 5%, response time 20ms).   4.2 Automobile Pressure Sensor The pressure sensor is the most used sensor in automobiles. It is mainly used to detect air pressure of airbags, the fluid pressure of transmission system, injection pressure, engine oil pressure, inlet pipe pressure, the fluid pressure of air filtration system, and so on. At present, the more commonly used vehicle pressure sensors are capacitive, piezoresistive, differential transformer, and surface acoustic wave.   The capacitive pressure sensor is mainly used to detect negative pressure, hydraulic pressure, and air pressure. The measurement range is 20kPa to 100kPa. Its characteristics are high input energy, good dynamic response characteristics, and good environmental adaptability.   The performance of the piezoresistive pressure sensor is affected by temperature, and it needs another temperature compensation circuit, but it is suitable for mass production; the differential transformer type pressure sensor has a large loss. The acoustic surface wave pressure sensor has the characteristics of small volume, lightweight, low power, low power, high reliability, high sensitivity, high resolution, and digital output. It can be used in the pressure detection of the automobile air suction valve and can work steadily at high temperatures.   4.3 Air Flow Sensor The flow sensor is mainly used for measuring the airflow and fuel flow of the engine. The intake volume is one of the basic parameters for fuel injection calculation. The Mass Air Flow Sensor (MAF) is a computer-controlled sensor that calculates the volume and density of the air taken in by the engine. This in turn ensures the right amount of fuel is used for optimized operating conditions. If this sensor is faulty, the car may stall and the fuel usage will be higher than necessary.   The function of the airflow sensor is to perceive the size of the airflow and transform it into an electrical signal to transmit to the electronic control unit of the engine. The measurement of airflow is used in the engine control system to determine combustion conditions, control air-fuel ratio, start, and ignition. There are 4 types of airflow sensors: rotary wing, Carmen vortex, hot wire, and hot film. The main technical indicators of the airflow sensor are: the working range is 0.11m3/min to 103m3/min, the working temperature is -40 to 120 degrees, and the accuracy is more than 1%.   4.4 Fuel Flow Sensor The fuel flow sensor is used to detect the flow rate of fuel, mainly with a water wheel and circulating ball. The dynamic range is 0 ~ 60kg/h, the working temperature is -40 to 120, the precision is 1%, and the response time is < 10ms. The position and speed sensor of position and speed sensor crankshaft and speed sensor is mainly used to detect engine crankshaft angle, engine speed, throttle opening, speed, and so on. It provides a reference point signal for ignition time and injection time and provides an engine speed signal at the same time.   4.5 Engine Speed Sensor Engine Speed Sensor is attached to the crankshaft and monitors the spinning speed of the crankshaft, which controls the fuel injection and timing of the engine.    Electromagnetic crankshaft position sensor At present, the position and speed sensors used in automobile are mainly AC generator type, magnetoresistance type, Holzer effect type, reed switch type, optical type, semiconductor magnetic transistor and so on. The measurement range is from 0 to 360 degrees, the precision is better than 0.5 degrees, and the bending angle is up to 0.1 degrees. There are many kinds of speed sensors, such as sensitive wheel rotation, sensitive power transmission shaft and sensitive differential driven shaft. When the speed of the vehicle is higher than 100km/h, the general measurement error is larger. The non contact photoelectric speed sensor should be used, the speed range is 0.5km/h to 250km/h, the repetition precision is 0.1%, and the distance measurement error is better than 0.3%.   4.6 Gas Concentration Sensor-oxygen Sensor A gas concentration sensor is mainly used to detect gas and exhaust emissions in vehicle bodies. The most important thing is the oxygen sensor. It detects the oxygen content in the exhaust gas of the car. According to the oxygen concentration in the exhaust, the air-fuel ratio is measured, and the feedback signal is sent to the microcomputer control device to control the air-fuel ratio to converge to the theoretical value.   The commonly used germanium oxide sensors (using the temperature of -40 to 900, 1%), chromium oxide concentration cell type gas sensor (using temperature 300 to 800 C), solid electrolyte chromium oxide gas sensor (using temperature 0~400, precision 0.5%), and two oxide oxygen sensor and two oxidation oxygen sensor. The Oxygen sensor measures the amount of unburdening oxygen that is present in the exhaust pipe and will indicate if the fuel is burning rich or lean. A faulty oxygen sensor will cause the car to idle poorly and jerk as well as cause high fuel consumption. Gas concentration sensor Compared with the germanium oxide sensor, the titanium dioxide oxygen sensor has characteristics like basic structure, lightness, cheapness, and strong resistance to lead pollution. The two zirconia micro ion sensor consists of calcium oxide stable oxidation plasma, porous platinum thick film working electrode, palladium/oxidation, and thick film parameter electrode, water layer, electrode contact, and guard layer. titanium dioxide oxygen sensor Among them, the stable oxidation of calcium oxide is deposited by reactive sputtering. Working electrodes and reference electrodes are made by thick film technology. The output voltage of the ideal A/F point is abrupt, the ratio of air to air is higher, the output voltage of the oxygen sensor decreases when the oxygen concentration is added in the exhaust gas; when the air-fuel ratio becomes lower and the oxygen concentration in the exhaust gas decreases, the output voltage of the oxygen sensor is increased.    The electronic control unit recognizes the mutation signal and corrections the injection volume, so as to adjust the air-fuel ratio accordingly and make it change near the ideal air-fuel ratio. At present, the NOx sensor is more and more strict for the diesel exhaust emission of NOx and PM. To cope with this limitation, it is not enough to improve the combustion mode of diesel engines. Therefore, post-processing technology is more and more valued. The selective reduction catalyst (SCR) method is one of the NOx purification techniques. The NOx in the tail gas can be selectively adsorbed to the catalyst. By spraying urea to the catalyst, the NOx can be decomposed into nitrogen, water, and discharge by reduction reaction.    The sensor in urea SCR can detect whether the dosage of urea water needed for SCR is suitable. This sensor is essential for reducing agents using nitrogen oxides (NOx) as urea water purifiers. Knock sensor detonation sensor is used to detect engine vibration, by adjusting ignition advance angle and avoiding detonation. Detonation can be detected in three ways, namely cylinder pressure detection, engine block vibration, and combustion noise.    The detonation sensors have magnetostrictive and piezoelectricity. The use temperature of the magnetostrictive detonation sensor is -40 C ~125 C and the frequency range is 5~10kHz; the piezoelectric detonation sensor has a sensitivity of 200mV/g at the center frequency 5.417kHz and has good linearity in the range of 0.1g~10g. titanium dioxide oxygen sensor has characteristics like basic structure, lightness, cheapness, and strong resistance to lead pollution. The two zirconia micro ion sensor consists of calcium oxide stable oxidation plasma, porous platinum thick film working electrode, palladium/oxidation, and thick film parameter electrode, water layer, electrode contact, and guard layer.     V. Application of Vehicle Sensor in Vehicle Chassis Electronic Control  System   Chassis sensors are sensors distributed in the transmission control system, the suspension control system, the power steering system, and the braking system. They are different in different systems, but the working principle is the same as the sensor in the engine, which is mainly used in the following.   Suspension sensors are used to control and control vehicle dynamics by interfering and adjusting the characteristics of vehicle suspension components. The continuous damping control system (ADC) consists of 4 control units, CAN, 4 wheel vertical acceleration sensors, 4 body vertical acceleration sensors, and 4 damper proportional valves.    According to the vehicle movement and the information detected by these sensors, the optimal damping coefficient of each wheel suspension damper is calculated, the height of the car is adjusted automatically, the change of the vehicle posture is suppressed, and the control of vehicle comfort, handling stability and driving stability is realized. The system is realized by the electronic control of the steering angle of the wheel.    The common system has the active front-wheel power steering system ESP, the active front-wheel superposition steering system AFS, and the active rear-wheel steering system RWS. The sensors used mainly include the speed sensor, engine speed sensor, torque sensor, and so on, which make use of these sensors to make the power steering control system realize steering control light, improve response characteristic, reduce engine loss, increase output power, save fuel and so on.   Whether it is ESP, AFS, or RWS, the principle of it is the driver's manipulation instruction, which senses the condition of the road surface by the sensor, and passes the network to the electronic controller and the actuator in the form of the electrical signal.   （1）The anti-lock braking sensor of the ABS system mainly uses the wheel angular velocity sensor to detect wheel speed. When the slip rate of each wheel is 20%, the brake oil pressure is controlled, the braking performance is improved, and the vehicle handling and stability are ensured. In this system, the wheel speed sensor is a very important part of ABS. It needs to provide reliable and precise wheel speed to ECU in time. The sensors have electromagnetic, Holzer, and magnetoresistance.   （2）TCS system, when the driving torque of the vehicle driving wheel is too large, the driving wheel will move relative to the ground. It is generally hoped that the slip rate of the driving wheel should not exceed 20%. This system of control for driving wheel skating is called the TCS system. It is developed on the basis of ABS. In most cars, TCS and ABS share an ECU. They identify and judge the driving condition of a vehicle based on the signal input by sensors.   （3）ESP electronic stabilization system ESP is an active safety system with good maneuverability and direction stability by adjusting the size and matching of the longitudinal force of the wheel to control the yaw motion of the car. The basic principle of ESP is to identify the expected motion state of a driver by means of sensors and operational logic. In order to identify the driver's expectation of the car and know the actual motion state of the car, the ESP system needs more sensors than ABS and TCS. They are hydraulic sensors of steering wheel sensor, vehicle yaw rate sensor, lateral acceleration sensor, and brake master cylinder.     VI. Sensor Application in Automobile Safety System   Safety is the primary factor for automobile consideration, and there are many sensors for safety, such as micro accelerometers for automobile airbags, surface micromachined gyroscopes of angle measurement rate, etc. Microaccelerometer micro accelerometer is usually composed of a parallel cantilever beam, one end of the beam is fixed on the frame and a small mass block (about 10mg) is suspended at the other end.    When there is no acceleration, the mass block is not moving. When there is a vertical acceleration, the mass block is moving, the acceleration is sensitive to the acceleration, and the signal is converted to the output by C/V transformation and phase-sensitive demodulation. According to the detection mode, the micro accelerometer has several kinds of piezoresistive, capacitive, tunnel, resonant, and thermal forms.   The capacitance micro accelerometer has high sensitivity, low noise, small drift and a simple structure. It is widely used in automobile airbag systems and anti-skid systems. The mass of capacitance micro accelerometer mass block moves downward when it has acceleration and changes the distance from another electrode on the frame. The displacement of mass movement can be obtained by measuring the change of capacitance.    The main structure is divided into suspension. The arm swing type and comb-like folded beam type are changed into other types. The structure of the former is relatively simple, and the bulk silicon processing method is mostly used. The simple pendulum type structure consists of the upper and lower fixed electrodes and the movable sensitive silicon cantilever beam electrode, the anisotropic corrosion of the semiconductor plane process, and the encapsulation of the electrostatic sealing technology. The latter can be regarded as the combination of the cantilever beam and the combination.    The design is much more complicated. The micromachining method is mainly based on surface sacrificial layer technology. The isotropic properties of the polysilicon material can guarantee the symmetry of the micromechanical properties, the precision of the batch processing is high, and the sensitive parts of this structure are small in size, and the monolithic integration of the peripheral circuits is realized. Micromachined gyroscope (MEMS) micromachined gyroscope (MEMS) is a vibrational angular rate sensor, which has attracted much attention in the application and development of automobiles. It is mainly used in GPS signal compensation and chassis control system for automobile navigation.   There are two vibration modes in the micromechanical gyroscope, one is the transverse vibration mode, that is, the mode of driving vibration, which is usually called the reference vibration, which will produce additional motion under the action of the Coriolis force; the other is the normal vibration mode, the sensitive vibration mode, the detection of the additional movement of the Coriolis force, and the angular rate information contained in the Coriolis force. According to the material used, the micromachined gyroscope is divided into two kinds of quartz and silicon vibrating beams. The quality factor of quartz material has the highest Q value, the top characteristic of the gyroscope is the best, but the quartz processing is difficult and the cost is very high.    Silicon material has complete structure, good elasticity, and easy to get high Q value micromechanical structure, which has become the mainstream of low-cost research and development at present. The structure of the silicon micromachined gyroscope, the vibration beam structure, the double frame structure, the plane-symmetric structure, the transverse fork structure, the comb tuning fork structure, the beam island structure are used. The driving modes for the reference vibration are electrostatic, piezoelectric, and electromagnetic driving. The detection methods of additional vibration caused by the Coriolis force are capacitive detection, piezo detection, and piezoresistive. Testing.    The gyroscope design with electrostatic drive and capacitance detection are the most common. Some of the products have been developed successfully. Vehicle monitoring and self-diagnosis sensor in-vehicle monitoring and self-diagnosis, the main application of vehicle sensors will be tire pressure monitoring, followed by sensors applied to cooling, braking, and other systems.    In addition, such as the use of light sensors in the luminance control system, the use of magnetic sensors and airflow velocity sensors in the driving system, the use of indoor temperature sensors, suction temperature sensors, air volume sensors, sunshine sensors, and humidity sensors in the automatic air conditioning system, and the use of azimuth sensors and speed sensors in the steering system.    The collision sensor is the main control signal input device in the airbag system. The effect is when the vehicle collides on the road, the collision sensor is used to detect the intensity signal of the car collision, and the signal is entered into the airbag computer. The airbag computer determines whether the inflatable element is detonated to inflate the airbag according to the signal of the collision sensor. After the transformation of many countries, many cars are also equipped with side airbags. When the car has a lateral collision, the airbag will also be inflated, so a system equipped with a lateral airbag is equipped with a collision sensor on the left and right sides of the car.    This is more humane in ensuring the safety of vehicle users. The lateral tilt angle sensor is an effective method to prevent the car from turning over the car during driving. It is an important measure to improve the safety of the car, especially the high gravity cars, such as the off-road vehicle and the double-deck passenger car, which is more necessary.   Take an example, an angle sensor made with the principle of gravity. The mass of the swing part is m, and the distance between the center of gravity and the shaft is L. When the car body tilts or curves, it can make the swing part deflect. The force analysis in Figure 1 is an ideal state without any friction. The force F is the result of the joint action of the sliding force F1 and the centripetal force F2. The force F is proportional to the tilting force, and the beta-generated deflection angle is proportional to the tilting force. The resultant force T of the gravitational G and F in the oscillating part is the tension of the pendulum, and the swing angle of beta =tg-1 (F/G) is independent of L. When the mass m is fixed, the beta is only related to F and is proportional.   In fact, due to the existence of friction on the shaft, the longer the L is, the larger the swing torque is, the higher the accuracy. Angle sensor is usually used as a sampling element in the control system, and its performance plays an important role in the whole system. The potentiometer angle sensor has been widely used in all kinds of control systems, but its disadvantage is the existence of sliding wear and electrical noise of the contact. The magnetic sensitive resistance angle sensor is a new pure resistive element made of semiconductor technology. It is characterized by no contact.    When the swing partial deflection, the flux of the magnetic resistor is changed to make the resistance of the magnetic sensitive resistance several times. The above changes fundamentally eliminate the electrical noise and improve the accuracy. All kinds of angle sensors have a damping function so that there is a short delay in response to the measured angle, which is beneficial for the control system.   VII. Other Major Automotive Sensors   Alcohol detection MEMS system is a new type of integrated alcohol sensor, which can adsorb oxygen according to the oxygen concentration in the environment and change the resistance value. In normal conditions, the element can keep a certain resistance value after the oxygen is adsorbed in the air, and once the air contains alcohol, the oxygen element on the surface of the element will react with the alcohol to reduce the resistance value.    By measuring the resistance value, we can detect the alcohol concentration in the breath. The alcohol detection MEMS sensor will be embedded in the sealed shell of the diameter 8mm, together with the signal processing circuit and so on, and will be embedded in the steering wheel together. Once the driver's exhaled gas contains alcohol, a safety alarm will be issued.    When the raindrop is hit on the glass of the induction zone, the intensity of the light reflected by the raindrop will change because of the rainfall or moisture content on the glass and changes the brushing frequency of the wiper. Or through the infrared electronic rainfall sensor to induce the amount of rainfall, and automatically adjust the speed of the wiper with the change of speed to improve the driver's driving convenience to make the driving safer.    The tire pressure monitoring system installs highly sensitive sensors on each tire to monitor the tire condition at any time in the driving state and transmit it wireless to the receiver through a sensor to enable the driver to grasp the condition of the tire at any time, to ensure the safety of the car, to prolong the service life of the tire and to reduce the consumption of the fuel. The most advanced direct tire pressure monitoring solutions include advanced warning systems, pressure, temperature, voltage and motion detection.   When the oil viscosity sensor changes the oil, it usually depends on the time or mileage specified by the manufacturer. A few manufacturers have adopted a more advanced way to calculate the oil exchange interval by recording engine speed and temperature.     VIII. Automotive Sensors Market Size--Its Market Trend   Because of the important role of automotive sensors in the automotive electronic control system and the rapid growth of the market demand, all countries in the world have paid great attention to its theoretical research, new material application, and new product development. The development trend of automotive sensor technology in the future is miniaturization, multi-function, integration, and intelligence.   The microsensor with low cost and high performance can be designed by means of micro electro mechanical system (MEMS) technology and computer-aided design technology. At the current level of technology, micromachining technology has been able to produce microstructures with different levels of 3D, and then produce tiny sensor sensors with very small sizes. Because the components are relatively small, the use is relatively convenient and efficient, making the economy improved.    Multifunction means that a sensor can detect 2 or more two characteristic parameters or chemical parameters, thus reducing the number of sensors and improving the reliability of the system. Integration refers to the use of IC manufacturing technology and fine processing technology to make IC sensors. Intelligentization refers to the combination of sensors and large-scale integrated circuits with CPU, which is intelligent, to reduce the complexity of ECU, to reduce its volume, and to reduce the cost.    In addition, the development of new materials is an important basis for sensor technology. Now new materials, such as optical fiber, nanomaterials, superconducting materials, have opened a new world for the development of sensors. With the development of research, more and more new sensor materials will be developed. The function of the sensor is not only related to its material, but also to its processing technology.    Micromachining technology has been increasingly used in the sensor manufacturing process. With the development of modern manufacturing technology, more advanced manufacturing technologies will be applied to the manufacture of automotive sensors. The principle of the sensor is based on various physical, chemical, biological effects, and laws, which enlightens people to further explore sensitive functional materials with new effects and to develop new sensors with new principles. This is an important way to develop low-cost, high-performance, multi-functional, and miniaturized sensors. FAQ   1. What is a sensor in automobile? Automobile sensors are intelligent sensors which can be used to control and process the pressure of oil, temperature, level of emission, coolant levels, etc. There are different types of sensors used in automobiles, but knowing the working of these sensors is essential.   2. How many sensors does a car have? Currently, each vehicle has from 60 to 100 sensors on board and we can expect that number to rise as cars get 'smarter'.” In fact, recent industry figures suggest the number of sensors is projected to reach as many as 200 per car based on current trends.   3. What is the importance of sensors in the automobile? Sensors monitor vehicle engines, fuel consumption and emissions, along with aiding and protecting drivers and passengers. These allow car manufacturers to launch cars that are safer, more fuel efficient and comfortable to drive.   4. How do vehicle sensors work? Using echo-times from sound waves that bounce off nearby objects, the sensors can identify how far away the vehicle is from said object, and alert the driver the closer the vehicle gets. Electromagnetic sensors create an electromagnetic field around the bumper, and offer an alert whenever objects enter it.   5. How many sensors does a F1 car have? 300 sensors. With help from over 300 sensors on each car, McLaren's F1 ECU deals with over 1000 input parameters and transmits more than 1.5GB of live data back to the garage during an average 300km grand prix.   6. Where are sensors located on cars? Depending on the vehicle engine model, you often have 1 to 4 exhaust gas temperature sensors. The sensors are installed on the exhaust pipe and the exhaust manifold, and sometimes also on the turbocharger. The sensors are often quite expensive and can be difficult to reach and replace; they often rust and get stuck.   7. How long do car sensors last? Newer oxygen sensors are supposed to work efficiently for 60,000 to 90,000 miles, depending on the model of your car. If your mechanic determines that your car's problem is due to a bad or failing oxygen sensor, the replacement shouldn't take long and you'll be ready to tackle many more miles on the road.   8. Do all cars have sensors? Modern cars have an increasing amount of sensors. Most cars have an oxygen sensor and a throttle position sensor, but parking sensors are optional. Professional mechanics agree that one of the most important evolutions to come about in recent years is the expansion of sensors to monitor mechanical systems.   9. How do I know if my upstream or downstream oxygen sensor is bad? A decrease in fuel efficiency can be a telltale sign that an O2 sensor is not performing as it should. This can happen because of a fuel mixture that is either too lean or too rich. Such a swing in A/F ratio is a sign that an upstream or control sensor is faulty.   10. What does a car do when the oxygen sensor is bad? If your oxygen sensor is failing, then its readings will be inaccurate, again, resulting in a sub-optimal fuel-to-air composition. Your car's performance isn't the only thing that is harmed by a malfunctioning oxygen sensor - it can do damage to the environment as your car's emissions will increase drastically.  

Warm hints: The word in this article is about 4000 words and  reading time is about 20 minutes.SummaryThe clock is the most important and special signal in the entire circuit. The movement of most of the devices in the system is performed on the edge of the clock. This requires that the delay of the clock signal is very small, otherwise it may cause an error in the timing logic. Therefore, it is very important for the design of FPGA to determine the factors of system clock and the delay of clock to ensure the stability of design. CoreClock in FPGA designPurposeDetermining the influencing factors of clock to ensure the stability of designEnglish nameField Programmable Gate ArrayCategoryDigital electronic circuitFunctionCreating digital circuitsFeatureTotally up to the designer to create a bit fileCatalogsCatalogsⅠ. What is Setup time and Hold timeⅢ. Analyzing with the help of timing diagram3. The composition of the state machine1. Synchronization between single bits and each pulse transmitted has at least 1 cycle width1. Setup timeⅣ. How to increase the clock working frequencyⅤ. An example showing a good method for state machine design2. The input pulse could be less than a synchronous circuit under a clock cycle width 2. Hold time1. Changing the line type for circuit wiringⅥ. The introduction of state machine Ⅱ. A basic model of synchronous design using a single clock2. Splitting the combinational logicⅦ. What we should pay attention when designing the clock in FPGA  IntroductionⅠ. What is Setup time and Hold timeThe clock is the most important and special signal in the entire circuit. The movement of most of the devices in the system is performed on the edge of the clock. This requires that the delay of the clock signal is very small, otherwise it may cause an error in the timing logic. Therefore, it is very important for the design of FPGA to determine the factors of the system clock and the delay of the clock to ensure the stability of the design.Learn how a clock drives all sequential logic in FPGA, from Flip-Flops to Block RAMs; The clock tells you how fast you can run your FPGA;This video demonstrates how to properly deal with multiple clock domains inside your design.1. Setup timeSetup time(Tsu) is defined as the minimum amount of time before the clock's active edge that the data must be stable for it to be latched correctly. Any violation may cause incorrect data to be captured, which is known as setup violation.2. Hold timeHold time(Thd) is defined as the minimum amount of time after the clock's active edge during which data must be stable. Violation in this case may cause incorrect data to be latched, which is known as a hold violation. Note that setup and hold time is measured with respect to the active clock edge only.Figure 1 Shows setup time and hold timeFigure 2 If data will change in tsu then it will cause setup violation and if data will change in thd then it will cause hold violation  DtailⅡ. A basic model of synchronous design using a single clockIn the same module of FPGA design, it often contains the combinational logic and the sequential logic. In order to guarantee the data in this logic interface can be processed steadily, then figuring out the concept of setup time and hold time is very important. Then we could be able to think about this following question:Figure 3 Shows a basic model of synchronous design using a single clockTco: Delay of the data output of the trigger;Tdelay: Delay of the combinational logic;Tsetup: The trigger's setup time;Tpd: Delay of the clock (negligible).T: clock cycleT3: D2 setup timeT4: D2 hold timeIf the first trigger D1 has a maximum setup time of T1max and a minimum of T1min, the combinational logic has a maximum delay of T2max and a minimum of T2min. The question is what conditions setup time T3 and hold time T4 of the second trigger D2 should be met, or what the maximum clock cycle given T3 and T4. This is the thing must be carefully considered in the process of design, because only by clarifying this issue can we ensure that the delay of the  combinational logic designed meets the requirements.Ⅲ. Analyzing with the help of timing diagramNow let us analyze this question with the help of timing diagram: let the input of the first flip-flop be D1, the output be Q1; the input of the second flip-flop be D2, the output be Q2;Given the clock is uniformly sampled on the rising edge, for ease of analysis we would discuss two cases, the first one: Assume that the delay of the clock Tpd is zero, which in fact, is often met in the FPGA design where the unified system clock it is generally adopted and the clock be input through the global clock pin, therefore the internal clock delay can be completely ignored. In this case, it is not necessary to consider the hold time, because each data maintains one clock tick while there is also delay line, that is, the delay based on CLOCK is much smaller than the delay based on data, so the hold time can meet the requirement. The setup time is what we should care about. If the setup time D2 meets the requirement, the timing diagram should be as shown as Figure 4.Figure 4 Shows the timing chart that meets the requirementsFrom the figure 4 we can see:T-Tco-Tdelay>T3That is Tdelay< T-Tco-T3During the setup time D2, the signal can reach D2 through the combinational logic D1, i.e. the data is already in Tsup before the second CLK arrive.Then it meets the requirement of setup time, where T as the clock period, the second flip-flop can pick up D2 on the rising edge of the second clock in this case. {D1 => setup time => hold time => trigger data output delay => combinational logic delay => D2 => ...}If the delay time of the combinational logic is too largeT-Tco-Tdelay < T3 (Tcox<D2 setup time)Then it will not meet the requirements. The second trigger will pick up an unstable state on the rising edge of the second clock, as shown in Figure 5, then the circuit will not work properly.Figure 5 The delay time of the combinational logic is too large to meet the requirementsSo you can deriveT - the Tco - T2max > = T3This is the setup time for D2.From the timing diagram above, it also can be seen that the setup time and hold time of D2 are not related to the setup and hold time of D1, except the combinational logic in front of D2 and the data transmission delay of D1. This is also a Very important conclusion, which shows that the delay has no additive effect.However, if there is a delay in the clock instead, the hold time must be considered in this case, together with the setup time. Most clocks with large delays are designed using asynchronous clocks, which is difficult to guarantee the data synchronization, so it is rarely used in actual designs. At this point, if the setup time and hold time all meet the requirements, you will see the output timing as shown in Figure 6.Figure 6. Clock has a delay but meets the timingIt can be easily seen from figure 5 that the Tpd is relaxed for the setup time, so the setup time of D2 must meet the requirements:Tpd+T-Tco-T2max>=T3 (T3 is the setup time of D2, T2max is the maximum delay of  combinatorial logic, Tpd is the clock delay)As shown in the FIG. 6, since the sum of setup time and hold time is a stable clock period (T), if the clock has a delay and the data delay is small, then the setup time will increase inevitably,  and the decrease of hold time goes with it. If it is reduced to not meet the requirement of hold time D2 , the correct data cannot be collected.That is T-(Tpd-Tco-T2min)T-(Tpd+T-Tco-T2min)>=T4 i.e. Tco+T2min-Tpd>=T4 (D2 hold time )From the formula above we could also figure out that if Tpd = 0, that is to say the delay of the clock is 0, then the same requirements goes with Tco + T2min> T4, however in practical applications the delay of T2 i.e. the delay of line is much larger than the trigger's hold time T4, it becomes not necessary to take the hold time into consideration.Figure 7 The clock has a delay and the hold time does not meet requirementsIn summary, if you do not consider the delay of the clock, the only thing you need to care about is the setup time, or the hold time instead. Then let us think about in FPGA design, how to increase the working clock in the synchronous system. AnalysisⅣ. How to increase the clock working frequencyFrom the above analysis, we can see that the requirements of setup time T3 for the D2 in the synchronization system is as follows:T-Tco-T2max>=T3So it is easy to derive:T>=T3+Tco+T2maxwhere T3 is the setup time Tset of D2, and T2 is the delay time of the combinational logic. In a design, T3 and Tco are both fixed values determined by the device, the only factor that we could control is the input delay of the combination logic T2. Therefore, by reducing T2 as much as possible, the clock working frequency can be increased. In order to achieve the reduction of T2 in the design, there are different comprehensive methods we can use.1. Changing the line type for circuit wiringAltera devices, for example, there are many bars in the quartus timing closure floorplan, so we can slice and dice them into rows and columns: Each bar represents 1 LAB, each LAB has 8 or 10 LEs in. The relationship of their routing delay is as follows: the same LAB (fastest) < the same row and column < different row and column. We could add appropriate constraints to the synthesizer (this should be given appropriate, generally 5% margin adding, for example, if the circuit works at 100Mhz, then adding constraints to 105Mhz is sufficient, because the excessive constraint could do a bad effect instead, and greatly increases the integration time) to make the relevant logic circuit wiring be placed as close as possible, thereby reducing the routing delay.2. Splitting the combinational logicSince the general synchronous circuits are more than a?single?stage latch (as shown in Figure 9), and to make the circuit stable, the clock period must meet the maximum delay requirement, and the maximum?delay of the longest path can be shortened before the operating frequency of the circuit be increased.As shown in Figure 8, we can decompose the larger combinatorial logic into smaller blocks and insert flip-flops in the middle, which can increase the operating frequency of the circuit. This is also the basic principle of the so-called "pipelining" technology.For the upper part of Figure 9, its clock frequency is subject to the delay of the second larger combinational logic. By appropriately distributing the combinational logic, excessive delay between the two flip-flops can be avoided and speed bottlenecks can be eliminated.Figure 8 Splitting combination logicFigure 9 Transferring Combination LogicHow to split the combinatorial logic in design, the better method should be accumulated in practice, but some good design ideas and methods also need to be mastered. We know that at present most of the FPGAs based on 4-input LUTs, if an output criteria corresponding is more than four inputs, then the multiple LUT cascade will be needed, thus introducing the delay of one-stage combinational logic. That is we want to reduce the number of combinational logic, the logic is nothing more than to make the input conditions as few as possible, so that less multiple LUT cascade need to be use, thereby reducing the time delay caused by combinational logic.The pipelining that we usually hear is a way to increase the operating frequency by splitting a large combinational logic (in the middle of which a singer or multiple stages of D flip-flops are inserted, thereby reducing the number of combinatorial logic between registers) to a smaller one. For example, a 32-bit counter, with a very long carry chain, will inevitably reduce the operating frequency, so we can split it into a 4-bit and a 8-bit one, whenever the 4-bit counter counts to 15 and triggers an 8-bit one, which enable the counter to be split and increases the operating frequency.Just as the same, large counters are generally moved out of the state machine, because if they, with usually more than 4 inputs, are used as state transition criteria with other conditions, they will increase the multiple LUT cascade, and then increasing the combination logic.Taking a 6-input counter as an example, we wanted to make a state transition after the counter counted to 111100, now because we put the counter out of the state machine, when it counts to 111011, a signal of "enable" is generated and then trigger the state transition, which obviously reduces the combinatorial logic.3. The composition of the state machineThe state machine generally contains three modules:An output moduleA module that determines what the next state isA module that saves the current stateThe logic used to form these three modules is also different. The output module usually contains both combinatorial logic and sequential logic; the module that determines the next state is usually composed of combinatorial logic; and the module that saves the current state is usually composed of sequential logic. The relationship between these three modules is shown in Figure 10.Figure 10 The composition of the state machineⅤ. An example showing a good method for state machine designThat is why when writing the state machine, the state machine is always divided into three parts according to these three modules. The following example shows a good method of state machine design: -----------------------------------------------------*/module arbiter2 (                    clock , // clock                    reset , // Active high, syn reset                    req_0 , // Request 0                    req_1 , // Request 1                    gnt_0 ,                    gnt_1                );//-------------Input Ports-----------------------------input    clock ;input    reset ;input    req_0 ;input    req_1 ;//-------------Output Ports----------------------------output    gnt_0 ;output    gnt_1 ;//-------------Input ports Data Type-------------------wire    clock ;wire    reset ;wire    req_0 ;wire    req_1 ;//-------------Output Ports Data Type------------------reg        gnt_0 ;reg        gnt_1 ;//-------------Internal Constants--------------------------parameter     SIZE = 3 ;parameter     IDLE = 3'b001 ,            GNT0 = 3'b010 ,            GNT1 = 3'b100 ;//-------------Internal Variables---------------------------reg        [SIZE-1:0] state ;        // Seq part of the FSMwire    [SIZE-1:0] next_state ;    // combo part of FSM //----------Code startes Here------------------------assign    next_state = fsm_function(req_0, req_1);//------------fsm_function--------------//function [SIZE-1:0] fsm_function;input     req_0;    //parameterinput     req_1;    //parameterbegin    case(state)        IDLE :                if (req_0 == 1'b1)                    fsm_function = GNT0;            else if (req_1 == 1'b1)                fsm_function = GNT1;            else                fsm_function = IDLE;        GNT0 :             if (req_0 == 1'b1)                fsm_function = GNT0;            else                fsm_function = IDLE;        GNT1 :            if (req_1 == 1'b1)                fsm_function = GNT1;            else                fsm_function =IDLE;        default : fsm_function = IDLE;        endcaseendendfunction always@(posedge clock)begin    if (reset == 1'b1)        state <= IDLE;    else        state <= next_state;end//----------Output Logic-----------------------------always @ (posedge clock)begin    if (reset == 1'b1)         begin        gnt_0 <= #1 1'b0;        gnt_1 <= #1 1'b0;        end    else         begin        case(state)            IDLE :                 begin                gnt_0 <= #1 1'b0;                gnt_1 <= #1 1'b0;                end            GNT0 :                 begin                gnt_0 <= #1 1'b1;                gnt_1 <= #1 1'b0;                end            GNT1 :                 begin                gnt_0 <= #1 1'b0;                gnt_1 <= #1 1'b1;                end            default :                 begin                gnt_0 <= #1 1'b0;                gnt_1 <= #1 1'b0;                end        endcase        endend // End Of Block OUTPUT_Endmodule Ⅵ. The introduction of state machineState machines are usually written in three segments to avoid excessive combinational logic.All we mentioned above shows how we could use the way of pipelining to split the combinational logic, but in some cases it is difficult for us to do that, and then what should we do?The state machine is such an example that we cannot add assembly line in the state decoding combinational logic. If there is a design of state machine with dozens of states, there is no doubt that its state decoding logic will be very large and this will be the critical path in the design. So what should we do?Just the same way, reducing the combinatorial logic. We can analyze the output of the state, reclassify and redefine them into a group of small state machines. By selecting the input (case statement) and triggering the corresponding small state machine, we can achieve a large state machine splitting into several small state machines. In the ATA6 specification (hard disk standard), there are about 20 kinds of input commands, and each piece of command corresponds to a variety of states. It is unthinkable to do it with a large state machine (nesting), however in the contrary, if you use the case statement to decode the command and trigger the corresponding state machine, in this way the module can run very fast.The key to increasing the operating frequency is to reduce the time delay from register to register, and the most effective method for reduction is to avoid large combinational logic, that is, to try to meet the four-input condition, reducing the number of LUT cascades, that’s mean that we could increase the working frequency by adding constraints, using a way of pipelining and splitting states.Ⅶ. What we should pay attention when designing the clock in FPGA1.Try to use only one clock in a module, and a module here means a module or an entity. In the design of multi-clock domain, it is better to have an extra special module for the isolation of clock domain. This allows the synthesizer to get a better results.2. Unless it is a low-power design, otherwise do not use the gated clock (gllobal Clock buffer such as IBUFG within FPGA) to control the input of clock edge of flip-flop, but use combinational logic and other timing logic (such as frequency divider) to generate signals used as the input of clock edge of flip-flop---all this is to reduce the instability of the design.3. Do not use the signals divided by counter as the clock of other modules, but  with the help of clock enable(CE). Otherwise, this clock-like manner is extremely unfavorable to the reliability of the design, and greatly increases the complexity of the static timing analysis .Ⅷ. Synchronization Between Different Clock DomainsIf two modules in a design using two respective operating clock, then at their interfaces there would emerge a phenomenon which called as Asynchronous Patterns. In order to ensure data correct processed, the two modules must be synchronized.There are usually two cases of different clock domains here (discrete clock source):1. the frequency of two clocks is different;2. the two clocks share a same frequency, but they are actually two separate clocks with no relation to the phase.Just as shown in the following two figures:Figure 11 The frequencies of two clocks are completely differentFigure 12 The frequencies of the two clocks are the same, but the phases are irrelevantThe data transmission between two clock domains usually adopts different synchronization methods according to different bit widths.1. Synchronization between single bits and each pulse transmitted has at least 1 cycle widthThis kind of synchronization is mainly used for the synchronization of some control signals. As shown in Figure 13 below:Figure 13 One bit synchronizer designThe following points are required to be explained for this synchronization:(1) synchronous circuit of figure 12 is actually called "one bit synchronizer", it can only be used for one bit asynchronous signal which must be wider than that of the Current stage’s clock, otherwise it may be unable to adopt this asynchronous signal.(2) why is the circuit in figure 13 can only be used in one bit asynchronous signals?When two or more asynchronous signals (control or address) simultaneously get into the current time domain and take control the circuit of current time domain, problems arise if these signals are all synchronized using the same circuit in FIG. 13. Skews has arisen between two or more asynchronous signals (control or address) due to connection delays or other delays, and then the skew is greatly enlarged via the synchronizer in Figure 13 when getting into the current time domain, or competition may caused and finally leading to an error in the time domain circuit.Figure 14 Problem-passing multiple control signals between clock domainsIf the asynchronous data bus is to enter the current time domain, the circuit in Figure 13 cannot be used either, because data change very randomly and the width of 0 or 1 has nothing to do with the clock pulse of the current time domain, so the circuit in Figure 13 may be unable to adopt the correct data.(3) Please note that the second trigger is not used for avoiding the occurrence of "metastable state", on the contrary, it can prevent the transmission of metastable state. In other words, once the first flip-flop becomes metastable (possibly), due to the second flip-flop, the metastability will not be transmitted to the circuit following.(4) The first-stage trigger has a metastable state, which means it will require a recovery time to stabilize again, or it is also called Withdrawal from metastable state. The recovery time plus the establishment time of the second-stage flip-flop (say more precisely, maybe also minus the clock skew) is less than or equal to the clock period, which can be easily satisfied. This is means thees two stages of flip-flop should be put together as close as possible, without any combinatorial logic between them or excessive skews to the clock, and then the second-stage flip-flop can adopt data stably and preventing the transmission of metastable state.(5) FF1 is the sampling output of FF2, so of course, what is output by FF1 is  what output by FF2, everything is the same except one cycle of delay. Note that “meta-stableit” means that once the data of FF1 enters, its electrical level would be indefinite and maybe incorrect. So although this method can prevent transmission of metastable state, it does not guarantee the data after the two-stage flip-flop is correct. Therefore, this kind of circuit always has a certain amount of fault-tolerance. This applies only to a some error-insensitive cases, but for other sensitive circuits, dual-port RAM or FIFO are better choices.2. The input pulse could be less than a synchronous circuit under a clock cycle width How is that possible? Has it not less than the original clock? For this case, the Feedback shown in Figure 15 below may usually be taken into consideration. The analysis of this circuit is as follows: Assume that the input data is high level, because the first flip-flop FF1 is high-level cleared, then all outputs should also be high and correctly adopted. On the other hand, if the input is low-level, data of FF1 would be forced to clear and the output level is zero, which ensures the correctness of the output.Figure 15 Synchronous circuit--input pulse may be less than one clock cycle width  Book SuggestionBuilding Embedded Systems: Programmable Hardware 1st ed. EditionThis is a book for embedded-system engineers and intermediate electronics enthusiasts who are seeking tighter integration between software and hardware. Those who favor the System on a Programmable Chip (SOPC) approach will in particular benefit from this book. Students in both Electrical Engineering and Computer Science can also benefit from this book and the real-life industry practice it provides.--Changyi GuDigital Integrated Circuit Design Using Verilog and Systemverilog 1st Edition, Kindle EditionFor those with a basic understanding of digital design, this book teaches the essential skills to design digital integrated circuits using Verilog and the relevant extensions of SystemVerilog. In addition to covering the syntax of Verilog and SystemVerilog, the author provides an appreciation of design challenges and solutions for producing working circuits. --Ronald W. MehlerPower Converters with Digital Filter Feedback Control 1st Edition, Kindle EditionThis book builds a bridge for moving a power converter with conventional analog feedback to one with modern digital filter control and enlists the state space averaging technique to identify the core control function in analytical, close form in s-domain (Laplace). It is a useful reference for all professionals and electrical engineers engaged in electrical power equipment/systems design, integration, and management.--Keng C. Wu Relevant information "Discussion on the influencing factors of clock in FPGA design"About the article "Discussion on the influencing factors of clock in FPGA design", If you have better ideas, don't hesitate to  write your thoughts in the following comment area. You also can find more articles about electronic semiconductor through Google search engine, or refer to the following related articles.To Solve the Problems of Cloud Skyrocket--Edge ProcessingFPGAs Power Facial Recognition Technology Was Issued by NECNew Software for C2000 MCUs Eliminates the FPGA in industrial designsCustomisable Ethernet switch designed for embedded applicationsMouser signs Intel FPGA board firm ReFLEX CES

Radio Frequency Identification (RFID) technology has been developed rapidly in recent years. The key is an automatic identification technology which uses radio waves to communicate. Compared with the traditional recognition technology, it has the advantages of fast recognition, large data storage and data updatable.  This is a video about brief introduction to RFIDThe basic principle of the data communication is the electromagnetic coupling between the reader and the electronic tag affixed to the object. This article will take the RFID technology as the research object, analyzing the basic definition of RFID, the components of the system, the working principle, operating frequency, the main application examples and development trend of RFID technology. In this article, we will make some intorduction to RFID and analyze how it will develop in the future.  CatalogI What is RFID?II Structure of RFID system2.1 Basic components of RFID2.2 RFID middlewareIII Basic working principle of RFID   technologyIV RFID operating frequency4.1 Low frequency 4.2 High Frequency4.3 Ultra-high frequency4.4 Active RFID technologyV RFID practical application examples5.1 Necessity of applying RFID technology   to retail logistics5.2 Why to use RFID technology instead of   existing technology5.3 Application of RFID technology in   retail industryVI Development trend of RFID application   system6.1 More powerful system compatibility6.2 System networking6.3 Greater system data volume6.4 High frequency systemFAQI What is RFID?Radio Frequency Identification (RFID) technology, also known as electronic tag, is a communication technology that uses radio signals to identify specific targets and read and write related data. And there is no need to identify the mechanical or optical contact between the system and the specific target. It can achieve fast reading and writing, non-visual recognition, mobile recognition, multi-target recognition, locating and long-term tracking management. The recognition work is not affected by bad environment, and it can achieve fast reading speed, read information safe and reliable. Therefore, RFID technology has a wide range of application prospects. Radio frequency identification is a non-contact automatic identification technology. It can automatically identify the target object and obtain the relevant data through the radio frequency signal. The identification work can be applied to all kinds of bad environment. RFID is a simple wireless system with only two basic devices. It is used to control, detect and track objects. The system consists of an interrogator and many transponders.Due to the rapid development of RF technology, transponders are also called smart tags or tags. The RFID reader can communicate wirelessly with the electronic tag through the antennas, and can read and write the tag identification code and memory data. A typical reader includes a high-frequency module, a control unit and a reader antenna. II Structure of RFID system2.1 Basic components of RFIDRFID system mainly includes four parts: electronic tag, reader, antenna and application software. The following picture is the block diagram of the system:RFID system structureFrom the above diagram, we can see that there are input and output of data in the module of reader and electronic tag, and the energy and clock are also transmitted in the two modules.2.1.1 ReaderReader is a device for reading (or writing) tag information that can be designed to be hand-held or fixed type. Hand-held is a smaller type used by supermarket cashiers; Fixed is a stationary reader placed by a logistics company at the door when goods are stored in a warehouse. As soon as the object swept by, the scan was completed in an instant.Reader working model2.1.2 AntennaAntenna is used to transmit RF signals between tags and readers.2.1.3 TagsTags are made up of coupling elements and chips. Each tag has a unique electronic code attached to an object to identify the target object. The following picture is the query tag diagram of readers. Reader query tag diagram2.1.4 Application softwareApplication software is a part of RFID system, which is software developed for different needs. It can read, write and control electronic tags through readers, and process and count the collected data. 2.2 RFID middlewareIn the application program, the API can connect to the RFID reader and retrieve the data from the RFID tag through the universal application program interface which can be provided by middleware. RFID middleware acts as a bridge between RFID tags and applications.In this way, even when the FRID reader category or application changes, the application still doesn't need to make any changes. It just need to configure the middleware accordingly. This can reflect the flexibility and importance of middleware.Practical application of RFID middlewareThe benefits that the application of RFID middleware can be brought to an enterprise are as follows:- According to their own business requirements and actual usage, enterprises can import the required data into the application software by self-configuring the RFID middleware parameters, which can fully reflect the flexible characteristics of RFID middleware.- The import of RFID data only needs to change the setting of RFID middleware when some changes occur in enterprise application software.- If you need to increase the number of RFID readers, then enterprises only need to do some related RFID middleware settings. It doesn’t need to change any related procedures, which reduce unnecessary trouble, and save time.- It shortens the implementation cycle of RFID application, and enterprises can directly import the relevant data of RFID.  III Basic working principle of RFID technologyA complete RFID system is composed of three parts: reader, tag with transponder and application software system. Its working principle is: Reader sends out the energy of a radio wave at a specific frequency to drive the transponder, and the circuit will send out the internal data. At this time, the reader will receive the data in order and interpret them, then send it to the application for some corresponding processing.RFID working principleThe information exchange between the reader and the transponder is usually half-duplex communication mode. In this case, the reader can provide the passive transponder with energy, timing and other related contents by coupling. In practical application, the object recognition information can be collected, processed and transmitted remotely through Ethernet and so on. Transponder is the main information carrier of its system. At present, most of the transponders in the market are composed of coupling elements (including coils, microstrip antennas, etc.) and passive application units composed of microchips. The reader can control and process the information center according to the structure and technology of RFID system information. Its reader is usually composed of a transceiver module, a coupling module, an interface unit and a control module. IV RFID operating frequencyAt present, the operating frequencies of RFID products are divided into low frequency, high frequency, ultra high frequency and so on. RFID products with different frequencies will have different characteristics. 4.1 Low frequency (125KHz ~ 135KHz)Related operation at this frequency is mainly done by inductive coupling. There is a transformer coupling between the inductor coil and the reader coil. The voltage which can be induced in the antenna of the inductor can be rectified by the action of the relative alternating field of the reader. Features:- Apart from some related effects of metal materials, the general low-frequency system can penetrate any material, but it will not reduce its maximum possible reading distance.- Readers working at low frequencies have no special licensing restrictions on the entire planet.- Low-frequency products have different packaging forms. The disadvantage of the best package is that it is too expensive, but it has a service life of more than 10 years.- The frequency of the sensor working in low frequency ranges from 120KHz to 134 kHz. The wavelength of this band is about 2500m. 4.2 High frequencySensors at this frequency will no longer need a coil to wrap it up. Antennas can be made by etching or printing. The related operations of sensors are usually done by load modulation. That is, by turning on and off the load resistance on the inductor, the voltage on the reader antenna will be changed, which can realize the amplitude modulation of the antenna voltage with the remote inductor. If people use data to control load voltages on and off, the data can be transmitted quickly from the sensor to the reader.Features: - Apart from metallic materials, the wavelength of this frequency can pass through most materials, but it will reduce the reading distance. Sensors often need a distance away from the metal.- Although the magnetic field region at this frequency decreases rapidly , a relatively uniform read - write region can be produced.- The system has good anti-collision property and can read many electronic tags at the same time.- Sensors usually exist in the form of electronic tags. 4.3 Ultra-high frequencyThe ultra-high frequency system will transmit energy by electric field. The energy of the electric field will not decrease rapidly. The reading distance of UHF is relatively long, and the passive system can reach about 10m. It is mainly realized by capacitive coupling.Features: - This frequency band has a good reading distance, but it is difficult to define the reading region.- It has a particularly high rate of data transmission and can read a large number of related electronic tags in a very short time.- The radio waves in the UHF band cannot pass through many kinds of application materials, especially water, dust and other substances. For high-frequency electronic tags, however, the tags need not be separated from metals.- Tag antennas are usually in two forms: long stripes and tags. The antenna has two different shapes: linear and circular polarization. It is designed to meet the needs of different applications in the market. 4.4 Active RFID technologyActive RFID is characterized by large amount of data transmission, long communication distance, high reliability, low transmitting power and good compatibility. Compared with passive RFID, it has obvious technical advantages.The basic ideas of RFID technology are: By adopting advanced technical means, people can automatically identify and manage all kinds of objects and equipment in different states.As a new kind of automatic identification technology, RFID technology has a great potential space for development in China, and it has been applied and developed in radio technology. V RFID practical application examplesIn this chapter, we will mainly expound the logistics analysis of retail industry based on RFID technology.5.1 Necessity of applying RFID technology to retail logisticsThe benefits of using RFID technology are not limited to the benefits of retail itself. With the use of RFID technology to create a new revenue stream, government institutions can reduce the loss and enhance the safety and security. At the same time, logistics companies, library systems can also reduce inventory costs.The application of RFID technology in retail can obtain the following benefits:   - Increase project securityTag items only allow objects to be tracked in a specified range or device. RFID technology can also improve the efficiency of inventory management. After all, inventory management is often a time-consuming and exhausting business for retailers.  - Serialization DataEach item has its unique identification number, so it is convenient to distinguish it from other items.  - Real time information flowThe changing state of a project can be quickly updated throughout the supply chain.  - Reduced manual participationRFID technology can track objects automatically without manual counting , data acquisition and bar code scanning , which can save labor cost and human error. The RFID technology provides a real-time visualization technology that allows inventory managers to monitor inventory supplies in real time. This reduces inventory costs and keeps inventory at an optimal level, which avoids shortage and other phenomena at the same time. 5.2 Why to use RFID technology instead of existing technologyThe question now is: why did retail change existing technology by adopting RFID? RFID technology is very similar to the existing bar code technology and non-contact memory. The use of new technologies can bring financial benefits (such as saving money) and can solve some practical problems that can not be solved by the existing technology. Compared with other automatic recognition techniques, RFID has significant advantages. 5.3 Application of RFID Technology in Retail industryRFID technology has been used in the retail industry such as smart shelf. The smart shelf is a kind of shelf which can prevent the phenomenon of product shortage. The shelf combines the RFID reader. Each unit shelf has a RFID tag that allows readers to track the inventory of their products. The main purpose of smart shelf is to support the replenishment at any time and to keep the shelves never out of stock, thus it has been widely used in retail industry and libraries. On one hand, it provides customers with information about the products; on the other hand, it provides inventory information for retail owners and can accurately locate the goods. The purpose of these applications is to offer better and more effective service to them. The use of these technologies will not be limited. It can make customers feel more effective and easier to shop.VI Development Trend of RFID Application systemIt can be predicted that future RFID systems will have the following technological trends: 6.1 More Powerful System CompatibilityAt present, because of the disunity of standards, products from many manufacturers are incompatible with each other. Therefore, it is required that the system should have a very strong compatibility, so that it can deal with the products of multiple manufacturers. 6.2 System NetworkingIn many applications, the data collected by different systems need to be processed uniformly, and then provided to users for use, which requires the management of RFID systems on a networked basis. The aim is to realize the remote control management of the system. 6.3 Greater System Data VolumeThe future RFID system will deal with a large amount of data, so it is necessary for the system to have a stronger data storage capacity and data processing capacity. 6.4 High frequency systemThe UHF RFID system has many advantages compared with the low frequency system, such as small size, long recognition distance, repeatable reading and writing, and no forgery. Therefore, with the decrease of manufacturing cost, the application of UHF system will be more extensive.  FAQ 1. What is RFID used for?Radio Frequency Identification (RFID) is the wireless non-contact use of radio frequency waves to transfer data. Tagging items with RFID tags allows users to automatically and uniquely identify and track inventory and assets. 2. What is RFID and how it works?RFID is a method of data collection that involves automatically identifying objects through low-power radio waves. Data is sent and received with a system consisting of RFID tags, an antenna, an RFID reader, and a transceiver. 3. What RFID means?Radio Frequency Identification (RFID) refers to a wireless system comprised of two components: tags and readers. The reader is a device that has one or more antennas that emit radio waves and receive signals back from the RFID tag. 4. Is RFID harmful to human?It is a non-ionizing type of radiation, but some researches show that it could have a negative impact on the human body in a long-term period [11, 12]. So, for the safety reasons, manufacturers of the RFID systems have limited the range of the RFID antennas used in their systems. 5. Is RFID tag and FASTag same?FASTag is a device that employs Radio Frequency Identification (RFID) technology for making toll payments directly while the vehicle is in motion. FASTag (RFID Tag) is affixed on the windscreen of the vehicle and enables a customer to make the toll payments directly from the account which is linked to FASTag. 6.What is RFID and its advantages?RFID technology automates data collection and vastly reduces human effort and error. RFID supports tag reading with no line-of-sight or item-by-item scans required. RFID readers can read multiple RFID tags simultaneously, offering increases in efficiency. 7. Why is RFID bad?Some negative effects are that its deadly, if RFID tags combine with static electricity you can die. Another negative effect is that the government is slowly taking away surviving resources and giving ultimatums, such as if you don't get the RFID tracking chip your public assistance will be terminated. 8.What are the disadvantages of RFID?a. Materials like metal & liquid can impact signal.b. Sometimes not as accurate or reliable as barcode scanners.c. Cost – RFID readers can be 10x more expensive than barcode readers.d. Implementation can be difficult & time consuming. 9.How do I charge my RFID FASTag?In order to recharge your FASTag sticker, just hit the Add Money option in your Paytm app. FASTag will automatically reserve some amount from your wallet, which can be used at toll plazas later. Do note that FASTag can be used only after 20 mins of adding money to the Paytm Wallet. 10. Can I use existing RFID for FASTag?If a vehicle already has an RFID tag, it might already be activated. When you buy the vehicle, RFID tag payment was also done. It might also have a minimum balance of INR 100 or 200 as is required by the bank. You can recharge it with your Customer ID or Wallet ID of FASTag. 11. How does RFID work without power?Passive RFID tags have no power of their own and are powered by the radio frequency energy transmitted from RFID readers/antennas. The signal sent by the reader and antenna is used to power on the tag and reflect the energy back to the reader. 12. What are the types of RFID tags?RFID tags can be grouped into three categories based on the range of frequencies they use to communicate data: low frequency (LF), high frequency (HF) and ultra-high frequency (UHF). Generally speaking, the lower the frequency of the RFID system, the shorter the read range and slower the data read rate. 13.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. 14. Does RFID require power?Active RFID tags possess their own power source – an internal battery that enables them to have extremely long read ranges as well as large memory banks. Typically, active RFID tags are powered by a battery that will last between 3 - 5 years, but when the battery fails, the active tag will need to be replaced. 15. What is the difference between a QR code and RFID?QR codes must always be “read-only”, whereas RFID tags can be “read-write”, depending on the radio frequency that's being used. ... So, not only are RFID tags futuristic and have more uses than QR tags, they also have many more applications. The read range is far superior for an RFID tag.  

Expo electronica--21st International Exhibition of electronic componentsFrom Apr. 17th to 19th in 2018, the EXPO ELECTRONICA,the 21st International Exhibition of electronic components,modules and systems will be held in CROCUS EXPO,MOSCOW,RUSSIA. As an exhibitor of the exhibiton, Kynix Semiconductor sincerely invites you to visit this exhibition. It is believed that you can have a better understanding of our company and we can form a stabler partnership.Following are some information about the EXPO ELECTRONICA. OverviewAs one of the largest international exhibition of electronic components,modules and systems both in terms of the number and importance of its exhibitors in Russia,ExpoElectronica exhibitions holds the title of the “Best exhibition in Russia” on the subject of electronics and accessories in all categories according to the Russian National Exhibition Rating. ExpoElectronica is an effective business platform to attract new clients and increase sales of electronic components, modules and systems to existing clients in Russia. Over 400 companies from 20 countries will take part in 2018 exhibition. More than 11 000 specialists from different regions of Russia and foreign countries are expected to visit the exhibition. expoelectronica-plan Exhibition profileSemiconductors;PCBs; Sensors and control devices; Micro- and nanosystems; Passive components; Displays; Electromechanics and connector technology; Embedded systems; Power suppliers; Electronics manufacturing services (EMS); Wireless components and modules; Automation systems; Microelectromechanical systems; Testing and measurement; Circuit design services; Software; LED products and components; NEW! Industry 4.0 solutionsAddressMoscow, 65-66km MKAD (International Exhibition Centre "Crocus Expo")ThemeBest exhibition in RussiaVenuepavilion 3, 65-66 km Moscow City Ring (MKAD), Moscow, RussiaScaletotal exhibitions area was 14 661 sq.mVisitorsOver 400 companies from 20 countries and more than 11 000 specialists from different regions of RussiaDateApril 17 (Tue.) - 19 (Thu.), 2018Well-Know ExhibitorsState Corporate ‘Rostechnologii’, Roselectronics , RAO ‘UES of Russia’, RUSNANO, Almaz-Antey, Zelenograd Innovation and Technology Centre (ZITT), Skolkovo Innovation Center and other.Russia represented electornic organisationsAngstrem, Micron, Svetlana, Meteor plant, JSC Moscow Electrolamp Plant, scientific research institute of gas-discharge devices Plasma, NPP Istok, NPP Pulsar and other.Our Booth Number D411 How to get to EXPO ELECTRONICAUrban transport:  Myakinino metro station (Arbatsko-Pokrovskaya line) - exit to Pavilion 3.By car: On the outer side of MKAD (66 km) - exit to the territory of Crocus City after the Volokolamsk highway, the index "Crocus City". On the inner side of the Moscow Ring Road (66 km) - the exit under the bridge in front of the Volokolamsk highway, the "Crocus City" signpost.ExpoElectronica mapAbout kynixKynix Semiconductor has founded over 10 years since 2008. These 10 years have witnessed our company's trials of becoming a better and better distributor and supplier in electronic components industry.In 2009, our company established the International Sales Department and became members of TBF and HKInventory. In 2010, we established cooperative relationships with accredited testing organizations like CECCLab, White Horse Lab, AAA...In 2013, we established a strategic partnership with dozens of well-known electronic components manufacturers including TI.In 2015,we reached an electronic components supply strategic partnership with Foxconn.Also ,our B2B trading platform was launched officially,whose members have exceeded 15,000 in 2017. Our partners in electronics field have increased to 700 up to now.In 2017, We attended Korea Electronic Show(KES), we won a lot of new partners and opened up kynix’s world market. Our advantages1.Strong operation system2. Good warehouse management3. Cooperation with advanced international testing companies4. Cooperation with international high standard logistics companies like UPS, DHL, TNT, FedEx5. Competitive supply from SumSung / Micron / BroadCom / Freescale / Atmel / Cypress and etc... After-sales ServicesGurantee1.Each product from Kynix has been given a  warranty period of 1 YEAR .During this period , we could provide free technical maintenance if there are any problems about our products.2.If you find quality problems about our products after receiving them , you could test them and apply for unconditional refund if it can be proved.But it's just on this premise that the product is not used and the packing is not damaged .Commitment to QualityKynix has always been laying emphasis on the quality of its products and maintaining a sound cooperative relation with electronic components manufacturers since its founding. It has been conducting quality-monitoring system following the rigid rules in terms of the quality of the product, delivery, and it's after-sales service.  It is claimed by Kynix that all products sold are 100% authentic. Each product has been tested carefully before being sent to the customer. It is our aim to be responsible for our customers and make them satisfactory. The 2017 Electronic Shows We have attened:In 2017,we attened the Korean Electronic Show whic held from 17 October to 20th October 2017 at the COEX Korea Exhibition Center in Seoul, Korea. Under the theme--Where the Creative Things are, there are more well-known exhibitors such as UNION SEIMITSU CO., LTD.; SILICONE VALLEY CO., LTD.; SANYO DENKI (THAILAND) CO.,LTD.; MORNSUN took part in KES. 2017 Korea Electronic ShowIt is  kynix’s honor to witness KES’s great success.We gained great benefits from KES.Over 10 thousand visitors from all the world saw kynix’s stand and asked about electronic semiconductors every day between exhibition period. What's more,we made cooperations with over 60 partners in the exhibition including Sumsung and LG. Kynix gained great benefits from KES ContactIf you have any questions, please contact us through our emails! Hope the exhibition finishes perfectly! We will be there and waiting for your coming! Want hintOpening hours of the EXPO ELECTRONICA is :April 17 from 10:00 to 18:00 on April 18 from 10:00 to 18:00 on April 19 from 10:00 to 16:00For a free visit you need to register and  receive an e-ticket at https://www.expoelectronica.ru . Without registration, the entrance fee is  500 rubles. 

Warm hints: The word in this article is about 2600 words and  reading time is about 15 minutes. In this article, we will mainly introduce the classification, performance, and development trends of electrical connectors. Connectors, as key components of current or signal connections, are also an important part of the industrial system. Not only in aircraft, rockets, connectors are also used in microphones and televisions, which all come in various forms. It builds bridges between circuits or other components that act as current or signal connections. Catalogs I. What Is A Connector?II. Classification of Electrical ConnectorIII. Basic Performance of ConnectorsIV. The Basic Structure of ConnectorV. Development trend of Electronic Connector Technology in the FutureFAQ  I. What Is A Connector?  Connectors, an electro-mechanical device, generally refers to electrical connectors. That is, a device connects two active devices and transmits current or signal.(Connector)Connectors are a kind of component that electronic engineers often come into contact with. Its function is very simple: to bridge the communication between the blocked or isolated circuits in the circuit, so that the current can circulate. The connector is an indispensable part of an electronic device. If you look at the path of the current flow, you will always find one or more connectors. The form and structure of connectors vary greatly, which is depending on the object, frequency, power, environment, etc. For example, connectors for on-court lights and hard drives, and connectors for rocket ignition are very different. But no matter what kind of connector is, it should ensure that the current flowing smoothly, continuously, and reliably. In general terms, the connector is not just used to connected current. With the rapid development of optoelectronic technology, the carrier of signal transmission in optical fiber system is light, glass and plastic also replaced the wire in the ordinary circuit. However, connectors are also used in optical signal pathways, which act the same as circuit connectors.   (Connector)The birth of the connector came from the manufacturing technology of fighter planes. Aircraft in battle had to be refueled and repaired on the ground, and the duration of stay on the ground was an important factor in the victory or defeat of a battle. Therefore, in World War II, the US authorities are determined to reduce ground maintenance time and increase the combat time for fighter jets. They first unitized the various control instruments and machine parts, and then connect them with the connectors to form a complete system. During repair, the faulty units are taken apart and the new units are replaced and the plane will soon be able to fly into combat. After the war, AT-T Bell Labs successfully developed the Bell telephone system, followed by the rise of industries such as computers, communications, and so on, which gives more opportunities for the development of connectors derived from stand-alone technology. II. Classification of Electrical Connector Due to the increasing diversity of connectors and the emergence of new structures and applications, it is difficult to classify and name the connectors by using a fixed pattern. Here we will discuss the classification of connectors on different basis.   1. By nature of useExternal connectors (for external housing), internal connectors (for internal housing). 2. By level of connectors> Level 1  DEVICE TO PACKING : Refers to the connection between IC chips and pins(Level 1)> Level 2 COMPONENT LEAD TO CIRCCUITRY: Refers to the connection between components and PC boards(Level 2)> Level 3 BOARD To BOARD: Refers to the interconnection of PC boards(Level 3)> Level 4 SUBASSEMBLY TO SUBASSEMBLY: Refers to the connection of subsystems to subsystems(Level 4)> Level 5 SUBASSEMBLY TO I/O PORT: Refers to the connection between subsystems to I/O port(Level 5)> Level 6 SYSTEM TO SYSTEM: Refers to the connection between system to system(Level 6) 3. By Processing MethodCrimp Type, I.D.C Type, Solder Type, Z.I.F Type 4. By Usage ModeWire to Board connector, Board to Board Connectors, Wire to Wire connector, socket, Input / output connector 5. By FormsPCB board connector, Flat cable connector, Coaxial cable connector, Embedded connector, Axial connector, Circular connector, Angular connector, Connectors for printed wiring boards 6. By StructureGeneral connector, Waterproof connector, Environment-resistant connector, Airtight connector, Refractory connector 7. By Operating FrequencyLow frequency connector, High frequency connector(Bounded at 3MHz) 8. By the Universality and Related Technical StandardsLow frequency circular connector, Rectangular connector, Printed circuit connector, RF connector, Fibre connector  (This video illustrates various types of electrical connectors or "Terminals" how they are used and how to connect them.) III. Basic Performance of Connectors The basic performance of the connector can be divided into three major categories: mechanical performance, electrical performance and environmental performance. 1. Mechanical performanceAs far as the connection function is concerned, the insertion force is an important mechanical performance. Insertion force is divided into insertion force and withdrawal force (withdrawal force is also called separating force), whose requirements are different. The maximum insertion force and the minimum separating force are stipulated in relevant standards, which indicates that the insertion force should be small from the application (thus having the structure of low insertion force LIF and no insertion force ZIF), but if the separating force is too small, the contact reliability will be affected. The insertion force and mechanical life of the connectors are related to the coating quality (sliding friction coefficient) of the contact structure (positive pressure) and the alignment accuracy (alignability). 2. Electrical performanceThe main electrical performance of connectors include contact resistance, insulation resistance and dielectric strength. > Contact resistance: High quality electrical connectors should have low and stable contact resistance. The contact resistance of connectors ranges from a few mOhms to tens of mOhms. > Insulation resistance: Insulation resistance is an index of insulation performance between contacts of electrical connectors and between contacts and shells, and its order of magnitude ranges from hundreds of megohms to thousands of megohms. > Dielectric strength: Also called withstand voltage or dielectric voltage, which refers to the ability to withstand rated test voltage between connector contacts or between contacts and housing. > Other electrical performanceElectromagnetic interference (EMI) leakage attenuation is used to evaluate the shielding effect of electromagnetic interference (EMI) of connectors, which is generally measured in the frequency range of 100MHz~10GHz. For RF coaxial connectors, there are also electrical indexes such as characteristic impedance, insertion loss, reflection coefficient, VSWR, etc. Because of the development of digital technology, in order to connect and transmit high-speed digital pulse signal, a new type of connectors, i.e. high-speed signal connectors, have emerged. Correspondingly, in addition to the characteristic impedance, some new electrical indexes have appeared, such as crosstalk, delay skew and so on. 3. Environmental performanceCommon environmental performance includes temperature resistance, moisture resistance, salt spray resistance, vibration and shock resistance, etc. > Temperature resistanceAt present, the maximum operating temperature of connectors is 200℃ (except for a few special high-temperature connectors), and the lowest temperature is-65 ℃). As the current produces heat at the point of contact, resulting in temperature rise when the connector is working. Therefore, it is generally believed that the working temperature should be equal to the sum of ambient temperature and contact temperature rise. In some specifications, the maximum allowable temperature rise for connectors at rated operating currents is classified. > Moisture resistanceThe invasion of moisture will affect the insulation performance of connectors and corrode the metal parts. The constant hygrothermal test conditions are as follows: relative humidity 90%~95% (according to the product specification, up to 98 ℃), temperature 40 ±20 ℃, the test time is prescribed by the product, minimum 96 hours.  > Salt spray resistanceWhen the connector works in an environment containing moisture and salt, its metal structure and contact surface treatment layer may produce electrochemical corrosion, which will affect the physical and electrical performance of the connector. In order to evaluate the ability of electrical connectors to withstand this environment, a salt spray test was prescribed. The connector is suspended in a temperature-controlled test box and ejected with compressed air with a specified concentration of sodium chloride solution to form a salt fog atmosphere. The exposure time is prescribed by the product specification for at least 48 hours. > Vibration and shock resistance They are the important performance of electrical connectors, especially in special application environments such as aviation and aerospace, rail, and road transport. It is an important index to test the mechanical structure of the electrical connector and the reliability of electrical contact. It is clearly stipulated in the relevant test methods. The peak acceleration, duration, impulse waveform, and the time of electrical continuity interruption should be specified in the impact test. > Other environmental performanceAccording to the operation requirements, the other environmental performance of electrical connectors includes leak proofness(Air leakage, liquid pressure), liquid impregnation(the ability of a specific liquid to resist the evil habit) and low pressure, etc.   IV. The Basic Structure of Connector The basic structure of connector includes: contacts, insulator, housing, accessories. (Basic Structure)1. ContactsContact is the core part of the connector to complete the function of an electrical connection. the contact pair is usually made up of positive contact and negative contact, which is electrically connected through the insertion of negative and positive contacts.Positive contacts are rigid parts with cylindrical shapes (round pins), Square column shape (square pins), or flat shapes (inserts). Positive contacts are generally made of brass and phosphor bronze. 2. InsulatorThe insulator, also known as the base or mounting panel (insert), is used to arrange the contacts according to the required position and spacing, and to ensure the insulation between the contacts or between the contacts and the housing. Good insulation resistance, voltage resistance, and processability are the basic requirements of insulator selection. 3. HousingHousing, also called a shell, is the cover of connectors. It provides mechanical protection for built-in insulating mounting panels and pins, and alignment when plugs and sockets are plugged in, thereby securing connectors to the device. 4. AccessoriesAccessories are divided into structural accessories and mounting accessories. Structural accessories are such as rand, positioning keys, dowel pins, guide pins, connecting rings, cable clamps, sealing rings, gaskets, etc. Mounting accessories are blots, nuts, screws, spring coil, etc. Coils, etc. Most of the accessories have standard parts and general parts.  V. Development Trend of Electronic Connector Technology in the Future Connectors, as a key component of current or signal connections, are also an important part of the industrial system. With the rapid development of personal mobile terminals, home intelligent appliances, information and communication industry, transportation and new energy industry, aerospace technology, artificial intelligence, medical electronic devices, and other fields, there are higher requirements for connectors in function, appearance, performance, and use environment. 1. Development trend of miniaturization and integrationIn order to meet the requirements of portable, digital and multifunctional electronic machines, as well as production and assembly automation, electronic connectors must adjust their product structure. Products are developed to small size, low height, narrow distance, multi-function, long life, surface installation, and other directions. Miniaturization means that the center spacing of electronic connectors is smaller, and the high density is the realization of a large core number. The miniaturization of consumer electronics requires miniaturization of components, thinness, and high performance, which also promotes the development of connector products towards miniaturization and small spacing. The miniaturization of components requires higher technical requirements. This requires a strong industrial mold base to effectively support. 2. Development trend of intellectualizationToday is a world of rapid information, no matter what kind of information or technology, people are demanding more and more. With the rapid development of information and communication data, wireless interconnection has come into our daily life. From the application of smartphones, smart wearable, UAVs, unmanned reality, intelligent robot, and so on, the development of electronic connector with IC chip and control circuit is an inevitable trend. This will enable the electronic connector to master the use of electronic devices more intelligently and improve the performance of the connector itself to achieve intelligent wireless bridging. 3. Development trend of high performanceHigh-speed transmission means that modern computers, information technology, and networking technology require the time scale rate of signal transmission to reach the MHz band and pulse time to sub-millisecond, so a high-speed transmission electronic connector (connector) is required.  In order to adapt to the development of millimeter-wave technology, RF coaxial electronic connector has entered the millimeter-wave working frequency band. High current is also an important development direction of many electronic connectors. In the modern high-tech industry, there are many connectors that are used under extreme environmental conditions.  Under the conditions of ultra-high temperature, low temperature, vibration, dampness, and heat, corrosive environment, electronic connectors can be used effectively and normally. This makes connectors more demanding in the selection of raw materials, structural design, processing techniques, new high-temperature-resistant materials, and the new electroplating coating processes.  FAQ 1. What are the 3 types of connectors?Electrical connectors are classified into three types based on their termination ends: board-to-board connectors, cable/wire-to-cable/wire connectors, and cable/wire-to-board connectors. Six levels of interconnection are normally seen in electrical connectors. 2. What are electrical connectors called?Twist-on connectors are also known as wire nuts, wire connectors, cone connectors, or thimble connectors. 3. What is the use of electrical connector?An electrical connector is an electromechanical device used to join electrical conductors and create an electrical circuit. Most electrical connectors have a gender – i.e. the male component, called a plug, connects to the female component, or socket. 4. Which tool is used to attach connectors to wires?PLIERS. ⟹Pliers are tools for gripping and cutting wires or connectors. 5. How many types of electrical connections are there?There are three categories of electrical connectors: light-duty, medium-duty, and heavy-duty. Each category heading refers to how much voltage the connector can handle. A light-duty electrical power connector can carry up to 250 volts (V) of a low current. 6. What are different types of connectors?Types of Connectors:Box-to-box or input/output.Wire-to-board.Chip-to-package.Package-to-board.PC board-to-board. 7. What is a connector?A connector is essentially the social equivalent of a computer network hub. Connectors usually know people across an array of social, cultural, professional, and economic circles, and make a habit of introducing people who work or live in different circles. 8. Why do we use connectors?Connectors are an important tool for writing proficiently in English. Their purpose is to join information together within a sentence. Using connectors correctly will help ensure the meaning of your sentences are clear for readers to understand. 9. How many types of electrical connections are there? There are three categories of electrical connectors: light-duty, medium-duty, and heavy-duty. Each category heading refers to how much voltage the connector can handle. A light-duty electrical power connector can carry up to 250 volts (V) of a low current. 10.What is the most popular type of connector?In the USA for networking and audio/video, the three most popular styles are LC, SC, and ST. LC and SC tend to be the most commonly used styles. Today, ST connectors are seeing more limited usage. You May Also Like:As the Development of Technology ,Connectors Should be Linghter,Smaller and SmarterHeavy Duty Connectors from TE Connectivity Offer A Range of Connectivity Solutions for InstallationHybrid Connector Combines Floating Contact Alignment with High Speed Transmission