| In this paper, the system design of MP3 carried in the car is accomplished, based on the design and debugging of software and hardware, as well as the correct system integrated debugging. The system makes use of the ripe single chip microcomputer technology and expands the external circuits based on the P89LPC935 microcontroller. With the aid of driving control chip SL811HST, according to the USB1.1 protocol, the firmware of AT89C51SND1 microcontroller accomplishes the enumeration of the USB mass memory device, management of the FAT files, realization of the audio files with suffix MP3, decoding MP3 audio stream into audio signal, transition of the analog and digit and deal of the audio quality.The system consists of six modules such as control module, digital audio process module, analog audio process module, radio module, key control module, liquid crystal display module. The design of the whole system is based on the two CPU-chip, namely, the microcontroller AT89C51SND1 with MP3 decoder and P89LPC935microcontroller. The external management of the whole system is controlled by a microcontroller P89LPC935 with high performance, high integration, low-cost, short operation time.Digital audio process module employs the embedded USB Host/Slave controller SL811HS and microcontroller AT89C51SND1 with MP3 decoder.Analog audio process module uses the 4-channel digital control audio processor PT2313L with high performance and reliability, the least external components,3 stereo inputs, 4 independent speaker outputs.The radio module selects the single chip TEA5767HN with low-power FM stereo radio. FM band is 87.5 to 108 MHz. The control of key is finished by two 8-bit, 4-channel multiplexed successive approximation analog-to-digital converter modules in the chip P89LPC935. The liquid crystal display module is finished by the driving chip UPD16431 A.The functions of system design of MP3 carried in the car are to play the MP3 audio document on the USB mass memory device and to receive FM stereo. |
