基于单片机的电子秤设计(同名13236).doc

电子秤Electronic scales are weighing technology in a new type of instrument is widely used in various occasions. Electronic scales and mechanical scales have more small size, light weight, simple structure, low price and practical value of strong, convenient maintenance and so on can be in a variety of environmental work, the weight of the signal can be Remote, the weight of display is easy to implement digital, easy-to-computer network, production automation, higher labor productivity. Scale labels in the supermarket is in the application of face value. A small label contains: name, price, weight, etc. 11 list in this small electronic label. Greatly accelerated the use of label machine sales pace, but also convenient for customers. Top barcode labels have many remarkable features of scale, Ethernet feature makes the management more convenient. Electronic Scale Classification (scales can be divided into mechanical and electronic type)1 How it works: electronic works in electronic components (weighing sensor, AD conversion circuit, microcontroller circuits, display circuit, keyboard circuitry, communications interface circuits, regulated power supply circuit circuit. 2 using the function: electronic weighing the use of modern sensor technology, electronics and computer technology integration, electronic weighing devices, in order to meet and solve real lifes fast, accurate, continuous, automatic weighing requirements, while effectively eliminating human error, to make it more in line with the management of legal metrology and industrial production process control applications. Three health scales are weighing the use of features in a category (divided into mechanical and electronic), inexpensive, it can help people to effectively monitor their own body weight changes, new products also can detect their fat content, but also Some human-oriented subsidiary functions. May not be part of measuring equipment. 4 Electronic Scale is a measurement of the state compulsory test apparatus, and his qualified products are test indexing the value of D values of e and subdivision standards, is subject to the protection of the national metrology products. In the electronic weighing there is a category called human scale products, which can test in the measurement sector, weighing very precise. Block diagram interpretation of the principle of electronic balance The first part of the electronic scale principle block diagram: Program K / B (button) Fx Sensors OP Zoom A / D converter CPU display driver display memory Workflow Note: When an object on the pan when the pressure facilities to the sensor that occurred deformation, so that resistance to change, while the use of excitation voltage changes, the output of a change in analog signal. This signal amplification by the amplifier output to the ADC. Converted to facilitate the processing of the digital signal output to the CPU operator control. CPU under the keyboard commands and program output to display this result. Until the show such a result. The second part of the scale of the classification: 1. According to principles of points: E-scale mechanical scale mechanical and electrical integration scales 2. According to the functions sub: Counting Scales Weighing Scale Pricing Scale 3. Purpose: Industrial Commercial Scales Special Scales Balance The third part of the scale types: 1. The full name of the desktop Scale refers to the volume of less than 30Kg electronic scale 2. The full name of platform scale refers to the volume within the 30-300Kg Electronic Scale 3. Loadometer full name refers to the volume of more than 300Kg Electronic Scale 4. Precision Balance 4th Part of the accuracy of classification: I Class: Special scales precision 1 / 10 Wan II level: high-precision scale 1 / 10000 precision of 1 / 100,000 III: the accuracy of scale 1 / 1000 precision of 1 / 10000 Class IV: Common Scale 1 / 100 precision of 1 / 1000 Part V of professional terminology: 1. Maximum weighing: an electron balance, excluding tare weight, the maximum load can weigh; 2. Minimum weigh: a electronic scales below the value that would have occurred when a relatively error; 3. safe load: 120% of the normal weighing range; 4. Rated load: normal weighing range; 5. permissible error: class test when the maximum deviation; 6. a sense of quantity: a single electronic scales can show the smallest scale; usually d to represent; 7. analytic capacity: a function with a count of the electronic scales, can distinguish the smallest scale; 8. Resolution: a counting function with an electronic scale, the internal capacity of a Resolution of a parameter; 9. Warm-up time: a scale used to achieve the targets of the time; 10. Accuracy: The full name of a sense of volume and volume ratios; 11. electronic scale use of environmental temperature: -10 degrees Celsius to 40 degrees Celsius 12. platform scale The table size: 25cm X 30cm 30cm X 40cm 40cm X 50cm 42cm X 52cm 45cm X 60cm Part VI electronic scale features: 1. To achieve long-distance operations; 2. To achieve automatic control; 3. Figures show that an intuitive, reduce human error; 4. High accuracy and resolution strong; 5. Weighing range is wide; 6 . unique features: buckle weight, withholding weight, zero, accumulated, warning, etc.; 7. maintenance simple; 8. size is small; 9. installation, calibration simple; 10. special industry, can be accessed by the printer or computer-driven; 11. Intelligent electronic scale, quick reaction, high efficiency; Part VII of the electronic scale inspection process: 1. First, the overall examination: whether the wear and tear; 2. Whether the boot: the boot sequence is from 0 to 9 in turn shows that figures are vague, can zero; 3. Whether the backlight ; 4. with the weight tests in weighing; 5. chargers is intact, can use; 6. parts are complete; Part VIII sensor type: 1. Resistive: affordable, high accuracy, widely used; 2. Capacitive: small size, low precision; 3. Maglev-style: special high-precision, high cost; 4. Hydraulic formula: the current the market has been eliminated; Display Type: 1.LCD (liquid crystal display): free electricity, energy-saving, with backlight; 2.LED: free electricity, power consumption, very bright; 3. Lamp: electricity, power consumption , high; K / B (button) type: 1. film button: contact type; 2. mechanical buttons: made up of many individual combinations of keys together; sensor characteristics: 1. rated load; 2. output sensitivity; 3. non-linear; 4. hysteresis; 5. repeatable; 6. creep; 7. 12:00 output effects; 8. rated output temperature; 9. 12:00 input; 10. input impedance; 11. output impedance; 12. Insulation Resistance ; 13. to allow excitation voltage; (5-18V) Part IX sensor damaged phenomenon: 1. Weighing not allowed; 2. Shows no return to zero; 3. Shows the number of bounce to judge the sensor + E,-E, + S,-S 1. The first to use resistance profile measurement 4-line 22 This resistance value, a total of 6 groups. The case of 400-450, compared with Europe + E,-E; if it is 350 in Europe, compared to + S,-S; for the 290 in Europe, compared to R-arm; 2. + E,-E terminated on the + _5V voltage Sensor correctly to exert a pressure, such as the output + _S increase, then the red table pens as + S, the contrary-S; 10th part of the high-precision counting scale features: 1.Kg/Ib unit conversion functions; 2. 12:00 display range adjustment function (GLH series does not) 3. Sampling speed adjustment function; 4. There are 10 groups memory function singlet; 5. may be at the same time the weight, quantity, the cumulative function (GLH only the number of cumulative) 6. can set the weight, the maximum amount of warning function; 7. automatic zero tracking, temperature linear correction; 8. deduction of withholding heavy weight and function; 9. Standby function; 10. there is zero shows zero tracking range and scope; 11. there is the battery voltage control to limit the function; Electronic scales are weighing technology in a new type of instrument is widely used in various occasions. Electronic scales and mechanical scales have more small size, light weight, simple structure, low price and practical value of strong, convenient maintenance and so on can be in a variety of environmental work, the weight of the signal can be Remote, the weight of display is easy to implement digital, easy-to-computer networking, process automation of production and improve labor productivity. Electronic Scale also has an automatic zero tracking, overload display of self-extinguishing characteristics. Mechanical scales, floor scale / land in the value (car value), weigh-bridges and other fitted force-sensitive sensors and microcomputer-controlled intelligent weighing instruments become intelligent digital electrical and mechanical balance (or the mechanical and electrical dual-use scales), to improve the mechanical balance of the measurement accuracy, with low cost, high reliability, simple installation and so on, without prejudice to the original mechanical scales to any transmission bearing structure. There are peeled, set to zero, the cumulative number of times, the cumulative weight (cumulative amount of valuation-based), auto-zeroing, auto-tracking and other functions. Weighing data can be directly printed or transmitted via computer networks, industrial processes can improve the level of scale and product quality, trade clearing with the scale can improve the credibility of incalculable social and economic benefits. Electronic Scale is basically a sensor, amplifier circuit, A / D conversion circuit, microcontroller control of display parts, switch matrix circuit, the keyboard circuit and power circuit. Weight sensor signals are converted to a corresponding electrical signal, after amplified into the A / D converted into pulses weight, through the SCM under the control of the analog voltage signals into digital. The digital conversion by the SCM program in line with the actual weight of the value of sending the number of display windows. MCU at the same time the keyboard and switch matrix for monitoring. According to the input parameter values, the program handled accordingly. Power circuit to provide the various parts of the operating voltage. Microprocessors such as 8050, HD404418F, 8031, etc. CPU. Highly versatile motherboard, different values of range and sub-degree scales, just adjust the jumpers on the motherboard and the DIP switch can be achieved, the only difference is that the sensor used with a rated carrying capacitySensor is a physical device or biological organ that can detect and feel the outside of the signal, physical condition (such as light, heat, humidity) or chemical composition (such as smoke), and Discovery of information to other devices or organs. Definition of sensorNational standard GB7665-87 sensor is defined as: can feel the requirements are measured and converted in accordance with the laws of certain signal device or devices available, usually composed of sensitive components and conversion devices. Sensor is a detection device, can feel the information being measured, and can detect sense of information, according to certain laws of transformation into electrical signals, or other forms of information required for output to meet the information transmission, processing, storage, display, recording and control requirements. It is the automatic detection and control of the primary link.The role of sensorPeople in order to obtain information from the outside world must help of sense organs. And rely on peoples own sense organs, the study of natural phenomena and laws, and production activities in their functions on far enough. To meet this situation, we need sensors. It can be said sensor is an extension of human senses, also known as electronic features.The arrival of the new technological revolution, the world entered the information age. In the course of the use of information, we must first resolve is to obtain accurate and reliable information, and sensors is to obtain information in the field of natural and production of the main ways and means.In modern industrial production, especially automated production process, the use of various sensors to monitor and control the various parameters of the production process, so that devices work best in the normal state or condition, and to achieve the best quality products. Therefore we can say, without a large number of good sensors, modern production base will be lost.In the basic science research, a more prominent position sensor. The development of modern science and technology into many new areas: for example, thousands of light years to observe the macro level of the vast universe, to observe microscopically small particles cm the world, vertical, to observe the evolution over hundreds of years of celestial bodies , a short response to the s moment. In addition, there was even a matter of deepening understanding, developing new energy, new materials, play an important role in a variety of extreme technology such as ultra-high temperature, ultra-low temperature, high pressure, ultra-high vacuum, powerful magnetic field, ultra-weak magnetic bagging, etc. . Obviously, to obtain a large number of human senses can not directly access the information,Not compatible with sensors is impossible. Many basic scientific research obstacles, first of all to obtain information on the object is difficult, and a new highly sensitive detection mechanism and the emergence of sensors, often lead to breakthroughs in the field. The development of a number of sensors is often a pioneer in the development of marginal subjects.Sensor has already penetrated into, such as industrial production, space development, marine exploration, environmental protection, resource survey, medical diagnostics, biotechnology, and even conservation areas and so most of the pan. It is no exaggeration to say that, from the vast space, the vastness of the ocean, as well as a variety of complex engineering systems, almost every modern project, are inseparable from a variety of sensors.Thus, the sensor technology in economic development, promote the important role of social progress is very clear. Countries in the world attach great importance to the development of this area. I believe in the near future, there will be a leap in sensor technology, to achieve status commensurate with its important new level.Sensor classificationDifferent views can be classified on the sensors: they transform principle (Transducer on the basic physical or chemical effect); their purpose; their output signal types and the production of their materials and processes.Working principle of the sensor can be divided into physical sensors and chemical sensors two categories:Sensor working principle of the classification of physical sensors that physical effects, such as the piezoelectric effect, magnetostriction, ionization, polarization, thermal, optical, magnetic and electric effects. Small changes in the amount of the measured signal will be converted into electrical signals.Chemical sensors, including those with chemical adsorption, electrochemical reaction, a causal relationship between the phenomenon of the sensor, the measured signal will be small changes in volume converted to electrical signals.Some sensors can not divided into physics, can not be divided into chemical classes. Most of the physics-based sensor is functioning. Many problems of chemical sensor technology, such as reliability issues, the possibility of mass production, prices, etc., solve such problems, the application of chemical sensors will have tremendous growth.Common sensor applications and the operating principle in the table below.1. In accordance with its purpose, the sensor can be classified as:Pressure sensitivity and the force sensor position sensorLiquid level sensor energy sensorSpeed Sensor accelerometer Ray radiation sensor thermal sensors2. In accordance with its principles, the sensor can be classified as:Vibration sensor humidity sensorGas Sensors Magnetic Sensors Vacuum sensor biosensors. Its output signal as the standard sensors can be divided into:Analog sensors - will be measured amount of non-electrical converted to analog signals. Digital sensors - will be measured non-electrical quantity into a digital output signal (including direct and indirect conversions). Ying digital sensors - will be measuring the amount of signal into frequency signal or short-period signal output (including direct or indirect conversion). Switch sensor - when a signal is measured to achieve a particular threshold, the sensor output corresponding to a specified low or high signal.In the role of external factors, all materials will be made accordingly, with the characteristic response. Them in the role of those outside the most sensitive material, that is, those with functional properties of the materials, and is used to make the sensor sensitive element. Material from the application point of view of the sensor can be divided into the following categories:(1) according to their type of materials used Metal mixture of polymer ceramic (2) by the physical properties of materials, sub- conductor insulator magnetic semiconductor (3) The crystal structure of materials, sub Crystal polycrystalline amorphous materials Sensor static characteristicsStatic characteristics of the sensor is on the static input signal, the sensor output and input between a relationship. Since then input and output quantity and time-independent, so their relationship, that is, the sensor can be a static characteristic algebraic equation without the time variable, or input for the horizontal, to its corresponding output for vertical axis and draw the characteristic curve. Characterization of the static sensors, the main parameters are: l