Design of Network Communication Module Based on RMII

The hardware design of homing system in torpedo has adopted a way of DSP+FPGA. DSP is used to process system information and FPGA (field programmable gate array) is used to control the bottom hardware. Considering the great amount of DSP in the system, 100 M Ethernet switcher is used to set up the interconnection of DSP. So any two DSP network node can conveniently do the data communication. It is by RMII (reduced medium-independent interface) that the Ethernet switch completes the network communication, but DSP don´t have homologous peripherals to match with it. Apparently, it is required to design the module of network communication in the FPGA, who can complete the conversion from DSP data format to RMII data format. In the design, the communication module is divided into transmit state machine and receive state machine. Each state machine has two 2 k bytes dual-port block memories, which are used as ping-pong buffers. One port of dual-port block memory is RMII data interface, whose width is 2 bits. The other port is DSP data interface, whose width is 32 bits. Writing command word to the address appointed can start sending data. Reading from the address appointed can judge whether data have been received. This module works in full duplex mode. Communication speed of this module is above 11 MBytes/s through tests, and the resource which has been used up is small. So this module can attain the requirements of the system.