Design And Research Of The Weighing Module In The Household Economic Smart Electronic Scales

The weighing technology, as a means of measurement, has been widely used in various fields since ancient time. The electronic weighing is the product of the combination of Weighing technology and Electronic technology, and its development has gone through three stages:analogous, digital and intelligent. Although the digital type is far better than the analog type, there are still some problems in it:non-unified interface causes difficult interconnection; the internal structure is complicated; inaccuracy caused by the lack of environmental compensation. In order to overcome these problems, intelligent electronic weighing emerged. Besides digital outputs, they usually include standard communication interfaces and inherently algorithms for compensation of non-linear, temperature, and creep.According to the evolution and the development trend of the electronic weighing, this paper selects household electronic scales as the study object, and puts the focus on economy intelligent electronic scales that are one direction of this future development of household electronic scales, and then committed to the research of the most critical intelligence weighing module. Resistance strain sensor technology is mature, low-cost, accuracy and its range is suitable and very suitable for household electronic scales, so this article selects resistance strain sensors for the intelligence weighing module.In this study, using highly sensitive resistance strain sensors, we explore suitable circuit connection, signal amplification processing, denoising and signal compensation. Sensors data were converted to digital form using high precision AD converter chip and send to upper computer by serial port. The weight value of the measured object is calculated by the software of upper computer. In accordance with the basic requirements of the design, the system can be divided into three modules, includes data acquisition modules, controller module and human-machine interaction module.The data acquisition module is composed of the pressure sensor, the signal amplification denoising processor, hardware compensation circuit and AD converter. Digital signal is sent to the controller after processed by AD converter, and then data is uploaded to PC through the serial port, and processed by PC. MCU AT89S52was selected for controller module, which communicates with data acquisition module by SPI bus and connects with upper computer by RS-232serial port. Software of MCU provides driver of SPI bus and serial port, and data calculating is processed in upper computer. The human-computer interaction module, software of upper computer, is to exchange the information between the man and the machine and to process the collected digital signal to get results. The design also provides overload alarm function that makes the design more humane and intelligent.The entire system module has main functions of intelligent scales:the simple intelligent sensor compensation (including circuit and algorithm), and standardized communication interfaces and protocols (RS232serial port and custom protocols). The module is simple and economic. Additionally, it can be built into a complete home economy smart electronic scale after adding the appropriate host table and display instrumentation. Because the entire system design concept is generic, low-cost and intelligent, it has broad market prospects for the production of this design.