Design of high-precision electronic scale based on 24-bit A/D conversion Introduction Material measurement is an important part of industrial production and trade circulation. Weighing devices are among the indispensable metrology tools. The electronic scale integrating modern sensor technology, electronic technology and computer technology has the advantages of fast weighing, intuitive display and easy wear, and can effectively eliminate human error and make it more in line with legal metrology management and industrial production process control. Application requirements are gradually replacing traditional mechanical lever measuring scales as mainstream products. This design uses AT89C52 single-chip microcomputer as the control core, combined with resistance strain type pressure sensor and A/D conversion chip HX711, designed a low-cost, high-performance electronic scale. The structure of the electronic scale in this design is shown in Figure 1. The principle is that the bridge varistor sensor converts the weight of the measured object into an analog voltage signal, and the strength of the voltage signal varies with the weight of the object. The NTC thermistor sensor measures the ambient temperature. The A/D converter chip HX711 is used as a metering and NTC temperature compensated converter to convert an analog voltage signal into a digital signal, and the resulting digital quantity is proportional to the weight of the object. The AT89C52 microcontroller is responsible for processing digital signals and displaying the quality of the object through the LCD. The unit price of the object to be measured is input by the button, and the single chip multiplies the object weight and the unit price to generate the total price, and displays it on the LCD display. In addition, the electronic scale can also print out information such as the quality, unit price, and total price of the measured object. Figure 1 Structure of the electronic scale Figure 2 shows a bridge varistor sensor. The bridge varistor sensor mainly uses the strain gauge deformation to convert the corresponding pressure into electrical parameters. The electrical parameters are filtered through a filter circuit and then input to an analog to digital converter. Figure 2 Bridge varistor sensor The complex filter circuit used is shown in Figure 3. The inductor of the component with high AC impedance is connected in series with the load to drop the large ripple voltage, and the component capacitor with low AC impedance is connected in parallel with the load to bypass the larger Ripple current. The filtering principle is similar to that of capacitor and inductor filtering. It is essentially a combination of capacitive filtering and primary LC filtering. It can reduce the pulsation component, make the output voltage smoother, and better resist external interference. Board To Board Connector,0.5Mm Floating Connectors,0.5Mm Dual Slot Board-To-Board Connector,20P Board To Board Connector Dongguan SOLEPIN Electronics Co., Ltd , https://www.wentae.com
