Wi-Fi High-fidelity Music Player Based On ARM9

With the enhancement of the embedded microcontroller processor’s performance and thepopularity of embedded operation system，embedded device based on the operating system isgradually applied to people’s life and work. The combination of digital audio technology andembedded computer technology has brought a broad prospect for the development ofembedded audio system.This subject focuses on high quality digital audio system and designs a high fidelitymusic player based on S3C2440A microprocessor. With embedded Linux operating system asa platform, this player realizes the high-quality playing of music. With the support of theoperating system, it can also realize the management and operation of the audio equipment bycalling the IIS equipment bottom drive. The IIS audio signal’s sending and interruptingservice is realized by the DMA controller, rather than by the interrupting inquires of CPU,which on the one hand saves CPU’s overhead, and on the other hand, greatly improves theefficiency of the signal’s transmission. The player will work in the proper environment byoperating the DSP digital signal processing equipment and the Mixer equipment and byconfiguring the system hardware, such as setting the frequency of the system’s IIS clock, etc.The difficulty as well as the focus of the subject is the design of the IIS audio driver dueto the close connection between the embedded system hardware driver and the bottomhardware and the high requirement of a good operating system as well as a good applicationprogramming interface. At the same time the player adds the USB signal decoding module, soit can be used as a USB sound card alone.DAC circuit of digital audio signal for eight times the oversampling digital inter-polation filtering process greatly improved the digital audio signal resolution.Digital interpolation filter is completed by the DF1706which is a product of TI company.The DAC converter PCM1704can support eight times digital interpolation filtering, and thehighest sampling frequency is96kHz. The DF1706is the ideal companion for TexasInstruments’ PCM170424-bit audio Digital-to-Analog (D/A) converter. This combinationallows for the construction of very high-performance audio systems and components.Oversampling processing lowers the requirements on the analog filter. Filtering circuit adoptsthree-level. GIC low-pass filter, for it has good noise and gain characteristic and good linearphase characteristic. Another important reason to choose the GIC filter is that it is designedbased on general impedance transforming topology structure, which, according to differentneeds, enables us to flexibly configure the circuit parameters and to easily design a filtermeeting various requirements. At present, since a lot of mobile phones have the function ofWi-Fi wireless Internet access, the player adds the88w8686Wi-Fi module so as to realize the wireless LAN.This paper, according to the general development process of embedded system,illustrates the detailed designing process of the system hardware and software. Meanwhile, itwill test the player, mainly including the timing analysis of the audio digital signal and thetest of the player’s function of restoring the original sound.