**Introduction**
With the growing awareness of environmental protection in China, issues such as urban pollution and energy shortages have become more prominent. According to recent surveys, the adoption of electric vehicles (EVs) is on the rise. As the number of EVs increases, so does the demand for efficient and cost-effective charging solutions. Currently, most community-based EV charging systems rely on coin-operated or time-based methods, which often result in high and unfair charging costs for users. This not only places an unnecessary financial burden on EV owners but also leads to inefficient resource utilization. To address these problems, a smart charging system has been developed. It allows users to charge based on actual power consumption, ensuring fair pricing. The system uses the SPI protocol to communicate with a computer, transferring critical data such as power usage, voltage, current, and electricity consumption for storage and analysis. This enables remote monitoring and control, significantly reducing the need for manual intervention.
**1. Overall System Block Diagram**
The device consists of several key modules: a power collection module, an A/D conversion module, a microcontroller unit (MCU) minimum system, a storage module, a display module, a payment module, and a charging module. The overall block diagram of the system is shown in Figure 1. The RN8208G single-phase power metering chip collects the power used by the user and converts the analog signal into a digital format through the A/D conversion module. The collected data is then stored on a TF card for long-term use and can be accessed by the MCU. Finally, the power usage and final electricity rate are displayed on a digital tube. Users can make payments using either an IC card or coins. The system's overall architecture is illustrated in Figure 1.
Figure 1: System Overall Block Diagram
**2. System Design** **2.1 Hardware Design** Based on the overall system design model, the embedded control system for the intelligent charging station has been optimized. The hardware design is built around embedded technology and includes modules such as power collection and measurement, payment, and communication. Below is a detailed description: (1) The power collection and measurement module is responsible for collecting, calculating, and transmitting power data. It features full digital gain, phase, and offset correction, ensuring accurate measurements even in the presence of external noise such as PCB or transformer interference. By improving the accuracy of small signals, the internal circuit interference is significantly reduced, resulting in more reliable and precise power measurements. This module supports SPI and USART communication protocols. Communication with the main microcontroller is simplified by controlling the high or low level of the IS pin on the RN8208G single-phase power metering chip. Additionally, an internal power supply monitoring circuit ensures stable operation during power-on and power-off events. The working circuit of the power collection and measurement module is shown in Figure 2.
Figure 2: Working Circuit of the Power Collection and Measurement Module
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