1 Introduction
In today's fast-paced society, with the continuous growth of the economy, people's living standards have significantly improved. However, this progress has also led to an increasing number of health issues, particularly obesity, which is now a major concern. As a result, more and more individuals are becoming aware of the importance of maintaining good health. Among various forms of physical activity, walking has emerged as one of the most effective and accessible methods for staying fit. Walking not only helps in improving cardiovascular health but also contributes to weight management and overall well-being. To make walking more efficient and measurable, pedometers have become increasingly popular. These devices allow users to track their daily steps, helping them stay motivated and monitor their progress. A pedometer based on a single-chip microcontroller offers high accuracy, reliability, and convenience, making it a widely accepted choice among users. By providing real-time feedback on step counts, these devices encourage consistent physical activity and promote a healthier lifestyle.
2 Overall Design
The pedometer system consists of several key components: an oscillating circuit, a reset circuit, a display circuit, and a button circuit, all powered by a battery. The system architecture is illustrated in Figure 1, showing how each component interacts to ensure accurate and reliable operation. This design allows the device to function efficiently, providing users with precise step counts and ensuring stability over time.
3 Hardware Design
3.1 Oscillation Circuit
The AT89C51 microcontroller features an internal oscillating circuit composed of an inverting amplifier. This circuit is essential for the proper functioning of the microcontroller. Without a stable oscillation, the system would fail to operate correctly. Any irregularities in the oscillation could lead to timing errors, especially in communication tasks. The oscillating circuit includes a crystal oscillator and two ceramic capacitors, which help stabilize the frequency and improve the performance of the system. As shown in Figure 2, this configuration ensures accurate timing and reliable operation.
3.2 Reset Circuit
To ensure the microcontroller operates reliably, a reset circuit is necessary. The primary function of this circuit is power-on reset, which initializes the system when the power is turned on. For the microcontroller to start properly, the power supply must be within the range of 4.75V to 5.25V, and the crystal oscillator must be fully stabilized before the reset signal is released. During the power-up phase, the microcontroller’s reset pin must remain high for at least 10 milliseconds to guarantee a complete reset. This setup is illustrated in Figure 3.
3.3 Display Circuit
This design utilizes a 4-digit LED common cathode display as the output interface. Each digit is made up of seven segments (plus a decimal point), allowing the display to show numbers and symbols. In a common cathode configuration, the cathodes of all LEDs are connected together and grounded. When a segment receives a high voltage, it lights up, forming the desired digit. To display different characters, specific segment codes are used, which activate the corresponding LEDs. This method is commonly referred to as a "segment code" or "font code." The display circuit is shown in Figure 4.
3.4 Button Circuit
Instead of using a sensor to detect movement, this design uses a mechanical button to simulate each step. Every time the button is pressed, the system increments the step count. This approach is simple and cost-effective, making it suitable for basic pedometer applications. The circuit is illustrated in Figure 5.
3.5 ADXL202 Sensor Circuit
For more advanced functionality, the ADXL202 sensor can be integrated into the system. This accelerometer detects motion and provides data that can be used to calculate steps accurately. The sensor module is connected to the microcontroller, and its circuit is shown in Figure 6.
4 System Software
The software of the pedometer begins by initializing the system and setting up the necessary interrupts. When a step is detected, the sensor captures the peak value, and after processing through four circuits, the step count is displayed on the LED screen. Each step increases the accumulator, and the updated count is shown in real time. Additionally, the microcontroller resets the display when an external interrupt is triggered. The overall process is depicted in the system flowchart shown in Figure 7.
5 Software Simulation
During simulation, the button K1 in the button circuit is connected to the P4.4 port of the microcontroller. The button generates an oscillating signal, which is converted into a digital signal and processed by the microcontroller. After conversion, the current step count is displayed on the LED. When the button is pressed once, the display shows "1," and subsequent presses increment the number accordingly. The simulation results are shown in Figure 8, demonstrating the effectiveness of the system.
6 Conclusion
This paper presents the design of a pedometer system based on a single-chip microcontroller. The system includes the microcontroller itself, display components, input mechanisms, and a real-time clock. Through careful analysis of each module, the hardware and software were designed and tested. The final simulation confirmed the system's functionality, proving that it can accurately track steps and provide real-time feedback to the user. This project highlights the potential of microcontroller-based systems in promoting a healthier lifestyle through simple yet effective technology.
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