IP Addressable Audio Playback System Based On The Network Microcontroller

The digital audio technology that rapidly develop greatly impact on the field of traditional audio transmission brought. In view of the traditional audio transmission has shortcoming that overcome difficultly, such as not manageable, cabling complex, difficult to achieve automatic switching, and so on , digital network specify in the right direction for the future undoubtedly the audio transmission,which has advantages of manageability, control, and strong data transmission capabilitiesBecause Internet network technology continue to expand, network more widly apply, the existing network facilities has been everywhere , network that is mature and widely popular provide the facilitation for data transmission. In addition, for the network communication protocol which ripely develop, it become possible that different hardware devices and applications to facilitate communicate conveniently. And applications, and rapid development of broadcasting technologies and multicast technology further promote the network multimedia transmission technology.DS80C400 is a network microcontrollers produced DALLAS, which is a high-performance structure network microcontrollers. DS80C400 has features of multi-node network, flexible I / O interface and stable ROM firmware, network protocol supports TCP IPV4/IPV6 and implement TCP, UDP, DHCP, ICMP and IGMP agreement. At the same time network protocol stack supports up to 32 TCP connections, and provides a good alternative of programme for the network interface.According to the basis of the DS80C400, with CPLD technology, network multicast technology and digital audio technology, the design complete IP addressable playback system. The system receive streaming audio multicast packets from the network and get audio data are processed by DS80C400. Under the control of CPLD , analog audio signal was played according to 44.1 kHz sampling rate, 16-bit sampling accuracy converted . Transmission of digital improve audio signals to a better controllability, confidentiality and anti-jamming capability. broadcast in the terminal as a node of Internet, has facture of only IP address, a addressable functions of good realization, allowing easy management and control.The first part of this paper introduced related knowledge of the streaming audio broadcast systems and package design.The second part introduce hardware design of network audio player terminal, which is divided into two modules of network access and streaming audio data processing. According to the core of DS80C400, the network access module implement the terminals with Ethernet interface, and receive streaming audio data packets; audio streaming data processing module as the core of CPLD, read data from the buffer zone, transmitted to the DAC line according to a certain amount of the total Timing. CPLD design use top-down methods, and apply VHDL language, which divided into MCU interface, the interface module RAM, DAC interface module.The third part introduce the software design, using assembly language to achieve, which include system initialization, join the multicast group, receive multicast packets, read and write data cache control.