Abstract: The Ethernet interface is the communication foundation for nodes in an Ethernet network. Located at the data link layer of the TCP/IP protocol stack, it is a crucial link in information transmission and management. This paper proposes the design and implementation of an embedded Ethernet interface. The hardware design utilizes the STR710 microcontroller and the CS8900A Ethernet control chip, and communication is achieved via TCP/UDP protocol. Relevant hardware connection diagrams and software implementation are provided, along with a case study of a voltage harmonic intelligent monitoring and harmonic suppression device based on ARM7. Keywords: Embedded system; ARM7; Ethernet interface; TwIP protocol stack; CS8900A Introduction With the rapid development of networks, the application of embedded systems is becoming increasingly widespread. Not only PCs can access the internet, but various embedded devices can also connect. Internet-connected embedded devices require the TCP/IP network protocol, which places higher demands on instruments and equipment used for monitoring the operation of power systems. Embedded systems, with their small kernel, strong specialization, system simplicity, and high real-time performance, have been widely used in various fields. Therefore, the networking of embedded devices is a current trend in technological development. In today's economic society, electricity load is increasing dramatically, and harmonic pollution of the power system is becoming increasingly serious, arguably the most significant indicator affecting the power grid. This paper, based on a case study of an ARM-based intelligent voltage harmonic monitoring and cancellation device, focuses on the design and implementation of an embedded Ethernet interface based on the STR710 processor with an ARM7 core. For details, please click: Design and Implementation of an Ethernet Interface Based on ARM7.