Research And Design Of Embeded IPPBX Based On ADSP-BF533

Today,as the rapid development in communications technology,a variety of communications technologies and communications standards have emerged. People put forward higher requirements on the communication technology integration.VoIP (Voice over IP) technology based on SIP (Session Initiation Protocol) protocol is to digital an analog voice signal and compressed through the VoIP network routed to its destination and then restore the speech.IPPBX (Private Branch Exchange Over IP) core softswitch technology is an open system theory, architecture, protocol and signaling, etc. to achieve PBX-based voice services and data communication.Softswitch IPPBX system can transmit data, voice and vedio as well as IP phone,regular telephone voice communication between terminals.This article topics from Anhui Sun Create Electronics Co., Ltd. R& D projects, the project aims to develop support for FXS (Foreign Exchange Station), FXO (Foreign Exchange Office), El and other interfaces embedded IPPBX, and the flexibility to select the configuration interface way.This article is based on the project.Firstly,Introduce the research background of this article and principle structure on the IPPBX were analyzed.In this section,I describ the SIP protocol,ananlog and digital interface,voice codec,etc.focus on the research and analysis of SIP process.Secondly, IPPBX structure and modular are designed and researched, including the hardware module master CPU Blackfin533, analog interface FXS, FXO, El control interface circuit design.And gives the FXS, FXO, E1 and other multi-interface model of the hardware design.in the design using the FPGA to mute voice identification system greatly reduces the processing load, the voice packet data transmission in savings on network bandwidth. Then on the IPPBX software architecture analysis,we introduced the transplant of U-boot on BF533 chip and uClinux systems hardware device drivers, we made assurance of voice quality by software when networking environment is poor. Finally, we made lots of tests for the function of the IPPBX for assuring the stability.the tests show that the IPPBX support FXS,FXO,and E1 better.and it is flexibility to choose the interface style.It can support 30 simultaneous calls.As mute control is done in the FPGA and we add adaptive voice cache in the software,we can still meet the needs of normal conversation when network environment is relatively poor.