Design And Implementation Of IP Voice Card

With the development of the technology of VOIP, Digital Signal Processor and PC bus interface, the IP Voice Card is getting more intelligent. However, the domestic IP Voice Card is not easy to upgrade due to the using earlier DSP and is not convenient to plug in or plug out due to using ISA or PCI bus. So, a kind of IP Voice Card where TI'S VC5416 is used is designed and implemented based on USB2.0 bus.Based on the having designed the system hardware and software structure, the functions of recording, playing and host's control are implemented by the way of software modularization on the DEC5416 general DSP board.According to the IP Voice Card total structure, the implementations of the hardware and software are presented distinguishingly. The AD/DA conversion, DMA transmission, system memory allocation and USB bus interface accessing are introduced. The software of IP Voice Card is composed by system program and application. Firstly, the system setting module, initialization module and CMD module related to the board are presented in detail. Secondly, the four modules of the application that are voice interface module, coding and decoding module, command parsing module and host control module are presented. Voice interface module implements the communication between DSP and Codec based on DMA transmission and the communication between DSP and host based on USB bus; Command parsing module parse the commands dispatched by the host control module; Coding and decoding voice are implemented by the coding and decoding module; Host control module sent user's request or dispatch command to board. In the last, system testing is presented.