Embedded Audio System Design

With smart phones, PDAs represented in the high-end embedded products terminal increasingly high prevalence, embedded system products of multimedia applications are more and more, in these multimedia applications, the requirements for the broadcast of audio files supported are becoming increasingly important.ARM (Advance RISC Machine), is the name of a corporation, the name of aseries of MCU and the name of a technology. At present, the MCU that have theARM IP core are used widely in industry control, consume electr onic product,communication system, network, wireless system and so on. The product used ARM technology is 75% in 32 bit RISC product market. ARM technology is infiltrating through our aspect of lives. Many semiconductor corporation purchase ARM core from ARM, and add appropriate peripherals depend on their used fields, then manufacture ARM MCU chip themselves. At present, tens of huge semiconductor corporation use ARM authorization, so there are more third party develop tools, software sustain ARM technology. Thus the products based on ARM are cost-effective, accepted easily by consumer and competitive.The main thesis of this work of this paper is to study the ARM XScale architecture based on the Intel XScale PXA270 processor basis, and to the processor core, the paper fully studies Philips audio codec chip and programs the audio recording and playback of the application in UP-TECHPXA270-S development platform.Firstly, the paper on embedded system explains a more details and UP-TECHPXA270-S development platform was introduced. UP-TECHPXA270-S is the main platform for teaching and research-oriented computer, electronics, automatic control of the high-end professional platform, microprocessor speeds in the 520 MHz stable operation can be run Linux 2.6.x, WinCE.net 5.0, Vxworks5.0 andμC / OS - II operating system, support for QT / E, and other embedded graphics interface, the drive and provide a complete application source code, not only for a computer, software, hardware and professional open embedded system design courses teaching platform, suitable for the broad masses in PMP, PDA, smart hand Machine manufacturers and research units as a reference design platform. UP-TECHPXA270-S platform for teaching and research by the processor core boards, motherboards and LCD composed of three parts. Core board and the motherboard interface design takes full account of the compatibility upgrade products, the core board can upgrade to PXA271, PXA272 microprocessor and motherboard resources unchanged. Moreover, in addition to the interface with rich resources, good scalability is UP-TECHPXA270-S platform is a major distinguishing feature. Secondly, the paper explains the audio codec system of relevant knowledge. Most of the market is now embedded processor support audio system, the hardware used is based on IIS bus or AC97 Bus Audio System Architecture. IIS (Inter-IC-Sound) Also known as I2S, which is PHILIPS company's proposed digital audio bus protocol, the adoption of the agreement can be directly embedded processors and external audio chips for data transmission. Now many of the audio chip and MCU are provided on IIS Bus support. In software, it is also an embedded system, embedded system with the characteristics, needs the support of the operating system. AC97 audio codec is (Audio Codec)'97 acronym. Intel AC97 is launched in 1997 specifically for audio equipment industry standards and design specifications. Its audio equipment in the general part of the figures (DSP) and analog segment (CODEC), left, which reduces electromagnetic interference, to obtain better sound quality. Current AC97 standard audio equipment in the PC is widely used. Along with the functions of handheld devices more powerful, AC97 standards have gradually entered the embedded system.Thirdly, after the analysis of the Linux operating system drivers work on the basis of principle, the paper studies the embedded linux driver for the development process and the establishment of a cross-compiler environment. As embedded systems hardware are unique, in general can not be installed distribution of Linux. So it is necessary specialized for specific target board Custom Linux operating system, which inevitably requires a corresponding development environment. Therefore we have adopted cross-development model. The so-called cross-compiler is: Using a machine running on the compiler compiler generating a source in another run on the target machine code process. Fourthly, the players are discussed in the design and realization in detail. The paper completes the development of a audio recording and playback applications. Through debugging, the application to the development board can work normally.Players design of the Common Interface Module visit, the realization of these interface to the player's visit to function module has brought convenience. When users running players, the players first initialization. After initialization, users will also be able to offer players the use of the recording and playback of WAV format audio files. The user interface will be called to operate nodes WavPlayer players in, WavPlayer nodes unified management File (File Operation nodes), the Splitter (file format parser), Codec (decoder / encoder nodes), Aio (audio input / output nodes). When users choose a WAV file player, the player part of the first reading of the paper and then proceed to the analytical document format, the paper received some information and pure data packets, WAV format for the judgment after decoding, audio decoding data received after basically drive directly through audio Fixed output to audio equipment. When users of sound recordings, the first player under the path specified by the creation of a WAV format, drive through audio equipment from the time of admission to be voice messages, and through encoder for encoding, and then encoded into the specified data and information in the document.Finally, the paper concluded. Embedded Audio System after a certain perfection and added can be used in many fields, such as digital multimedia terminals, voice recognition systems. The authors designed system can be extended on the basis of more applications, is the voice of the people-to-people exchange carriers, the reality of life is an indispensable and important component of the author's work is very meaningful.