The Development Of The DSP Driver Program Of IP-Phone Based On The AC494 Soc Platform

VoIP is also known as IP-Phone, which is a kind of Internet real-time transmission of voice technology. Although Internet that uses packet switching technology may not provide the same voice communications services as traditional telecommunication networks, but the IP network has two outstanding advantages:low cost and wide coverage. This makes the VoIP technology is growing rapidly. Following the improvement of network environment, some problems such as latency, problems of jitter and high packet loss rate would no longer be the bottleneck of the development of IP-Phone, but the IP-Phone products do not occupy the market as expected. Although IP-Phone technology is advanced and outstanding, it is still unable to get the favor of customers. IP-Phone products were unattractive for private customers largely due to the high cost of customer device.SoC technology that is the gradual emergence of the field in the embedded is likely to change the IP-Phone's fate once again. SoC which stand for System On Chip, is a technology that is a microcontroller, DSP co-processor and other peripheral interfaces integrated in a chip. SoC device has small size, few power consumption and low cost. Due to the integration of many devices on the same piece of silicon, SoC can minimize the hardware costs; In addition, SoC is based on IP-multiplexing which can shorten the development time, thereby reducing software development costs.In this paper, the SoC skills will be applied to development of IP-Phone and would be considered as a method to resolve current problems. The article describes how to develop softwares of IP-Phone on the SoC. The whole task is divided into two parts:embedded systems transplantation and development of DSP driver program.The task of embedded systems transplantation includes bootloader program transplantation, operating systems transplantation and filesystem make. This paper describes how to setup the MontaVista's cross compiling tools, how to modify, compile, download and launch PSP_Boot and Linux kernel program and how to make CRAMFS filesystem in detail.DSP driver program include two parts:drivers in the kernel space and console command applications in the user space. In fact, DSP kernel drivers is designed to provide workspace and API for DSP core because DSP is contained by SoC. Its functions contain downloading firmware, initializing DSP and communicating with MIPS. The console command applications could be designed to provide man-machine interface and mechanism of exchanging messages between DSP and others.In addition, it might be depicted in this paper what would be done in the next stage to perfect this product and how IP-Phone mignt develop in future.