Electronic Scale Product
Since July 2021, after about two months of intermittent efforts, the author has finally completed the installation and debugging of the smartphone electronic scale, which can measure up to 10 kilograms.
During the long installation and debugging process, two technical articles from the WeChat public account “A Xuan Physics Teaching Research Room” were referenced. The author, Teacher Mei Xiaoxuan from Beijing He Ping Street No. 1 Middle School, also provided continuous and strong technical support, for which I express my gratitude.
A Xuan Physics Teaching Research Room
HX711 Weighing/Tension Sensor Experiment
Phyphox HX711 Impact Force Measurement Experiment
During the experiment, the connection of HX711 was always wrong, which was caused by the difference in wire color distribution provided by the manufacturer and that in the reference literature; at first, I stubbornly adhered to the absolute correspondence of colors, which always resulted in errors; later, I thought that the product must have been tested at the factory and should be foolproof, plug and play; I decisively abandoned the color correspondence and connected directly, and it worked on the first try.
HX711 Connection Method
When connecting the ESP32, there were also many errors for a long time; following the connection method in the reference literature, the data output was always wrong, and the quality time function graph on the smartphone continuously output periodic spikes. After multiple attempts, I accidentally discovered that when the HX711 was connected to a 3.3-volt power supply, the data output was normal.
ESP32 Connection Method
Although the electronic scale had data output, the output value of the electronic scale was inconsistent with the 500-gram weight used for testing. Therefore, I performed calibration within the applet, and when placing a 500-gram weight on the electronic scale, the reading was exactly 500 grams.
Curve and Value Display Method
It should be noted that after calibration, the electronic scale is accurate around 500 grams, but when the measured value deviates from 500 grams, there is a measurement error of about ±3 grams.
Thus, we have added a force sensor to the Phyphox mobile experimental design field, and in the future, we can conduct scientific inquiry experiments related to mechanics.