The electronic scale is an advanced weighing device that integrates modern sensor technology, electronic systems, and computer science to meet the growing demand for fast, accurate, continuous, and automated weighing in real-world applications. By eliminating human error, it aligns well with legal metrology standards and industrial process control requirements. This system is designed around a 51-series single-chip microcontroller and uses the HX711 analog-to-digital (A/D) converter chip, which is known for its high precision and stability.
The load cell senses the weight and generates a weak millivolt-level voltage signal. This signal is then processed by the HX711, a 24-bit A/D converter chip specifically designed for high-precision electronic scales. It communicates with the microcontroller via a two-wire serial interface, allowing the MCU to read, calculate, and convert the data before displaying it on the LCD screen.
A matrix keyboard allows users to input unit prices, enabling the scale to automatically calculate the total cost and display it on the screen. The power supply provides stable energy to the microcontroller, the HX711 circuit, and the sensor.
The HX711 circuit is crucial for converting the analog signals from the load cell into digital values. It features built-in gain control and high accuracy, making it ideal for precise measurements. The STC89C52 microcontroller serves as the brain of the system, handling all the processing tasks. The LCD display provides a clear visual output of the measured weight, unit price, and total amount.
The matrix keyboard includes digits 0–9, a decimal point, and five function keys. Its scanning mechanism uses ROW1–ROW4 and COL1–COL4 signals, allowing the system to detect key presses accurately. When a key is pressed, the corresponding column outputs a low signal, enabling the system to determine the exact key pressed.
A sound and light alarm circuit is integrated to alert users when the measured weight exceeds the set range. In such cases, the buzzer sounds, and the alarm light turns on. The power circuit is powered through a USB interface, providing a 5V supply. The PL2303 chip facilitates programming and communication via the USB port.
In terms of software design, the main program utilizes a timer to perform weighing every 0.5 seconds. The flowchart outlines the process, including the clock interrupt, keyboard scanner, and main program execution. Key functions include initializing the system, handling interrupts, and managing user inputs.
The code includes header files, macro definitions, and variable declarations. Functions like `int2str` convert integers to strings for display, while `To_Zero` calibrates the system before each measurement. Other functions handle the display of weight, unit price, and total cost, ensuring accurate and user-friendly output.
The program also manages the keyboard input, triggering actions based on user interaction. A timer interrupt ensures periodic weighing, and the system checks if the weight exceeds the threshold, activating the alarm if necessary. The software is structured to be efficient, reliable, and easy to modify for different applications.
Shenzhen Essenvape Technology Co., Ltd. , https://www.essenvape.com