In a large-scale underwater system, different communication protocols are typically adopted to suit the characteristics of various subsystems. Serial communication, with its strong anti-interference capability and long transmission distance, is suitable for subsystems requiring long-range communication. The MIL-STD-1553B bus offers extremely high reliability and real-time performance in data transmission, making it suitable for inertial navigation and fire control subsystems that demand high signal accuracy and real-time performance [1].

DSP can process data quickly and offers high integration and stability, making it a mainstream processing chip in the control field [2]. However, the DSP's on-chip communication resources are limited and fixed, which can lead to poor system scalability. Furthermore, frequent interrupt responses by the DSP can negatively impact its operational efficiency.

Compared to DSP, FPGA offers the following advantages: it supports parallel operations, can process multiple work units simultaneously, and can achieve real-time data transmission [3]. FPGA can implement logic interfaces found in traditional designs through its own programming, which greatly reduces the complexity of peripheral circuit design and hardware design, and significantly enhances system scalability.

This paper utilizes a DSP chip as the main processor, responsible for application layer design and information scheduling during system operation. An FPGA is employed as the system's coprocessor to acquire multi-channel RS-422 serial signals and cache data. Concurrently, the FPGA is used to implement the functions of BU61580 and extend them as required