High precision electronic balance based on STM32

FAN Yi， QIN Hui-bin
（College of Electronic Information， Hangzhou Dianzi University， Hangzhou 310018， China）

Abstract： The electronic balances on the market have some defects，such as high cost，low precision and low operation speed. Aiming at solving these problems of electronic balances，the STM32 which has high operating frequency and enhanced functions was used as a controller to design a high precision electronic balance.  The stability of circuits was improved by using HX711 which integrates a 24 bit A/D converter and an amplifier. In order to reduce the complexity of circuits，the digital filtering method was used to filter，and the moving average filter was used to filter digital analog signal from the A/D converter. Verification experiments and error analysis were carried out. The relation between true value and measured value was built. Based on the error analysis，the accuracy was estimated. The experimental results indicate that，this design has a maximum range of 300 g and a precision of 0.01 g. Its repeatability error and indication error are less than or equal to 0.02 g and it reaches a stable reading in about 10 seconds.
Key words： high precision； electronic balance； STM32； HX711