An intelligent interface audio system design (1)

0 introduction

With modern electronic technology development, interface technologies are more and more rapidly, and the USB interface it is in this context develop and grow up.

In a traditional hardware architecture, the interface is considered to be part of the external device, each interface is generally can only connect to the same device. Although the adoption of the so-called "daisy chain" (daisyohain) ways to put some of the same device connected to the same interface, but you cannot mix different types of devices connected to the same interface, since the USB device is getting more and more abundant species, in order to meet this demand, here a USB 2.O interface solutions, through the USB interface to read the various USB devices via SD card interface, read various mainstream storage card. The programme supports the commonly used USB storage devices (including USB flash drive hard disk/USB/USB/USB Reader) and SD card (including the standard capacity SD cards and high-capacity HC-SD card and Protocol compatible MMC card and TF card). This article presents an intelligent interface for all hardware audio system solutions that enable audio system extensibility further enhanced, in principle, can be connected to the current most popular storage devices, a device to multiple extensions. To further integrate existing resource utilization, has certain economic and social benefits, and uses the entire hardware decoding and SCM block work-power control mode, the power consumption of the entire system down to traditional similar equipments for 50 per cent, in line with the theme of energy saving and environmental protection in China.

1 hardware system design

1.1 chip overview

ATmegal28 is based on enhanced AVR RISC architecture and low-power 8-bit CMOS microcontroller.

Because of its advanced instruction set, and single clock cycle instruction execution time, ATmegal28 data throughput rates up to 1 MHz MIPS/. AVR kernel with rich instruction set and 32 universal working registers. All the registers are direct and arithmetic logic unit (ALU), makes 1 instruction can be in one clock cycle to access two separate registers. This structure has greatly enhanced the efficiency of the code, and has more than ordinary CISC microcontrollers up to 10 times higher data throughput rates.

CH3768 is file management control chip for SCM system read and write u disk or SD card file.

CH376S supports USB device and USB host mode, and built-in USB communication protocol of the firmware. Processing Mass-Storage mass storage device of a private communication protocol firmware; SD card communication interface firmware and FATl6, FAT32 file system, as well as FATl2 management firmware support common USB storage device and SD card.

VSl053B is 1 single MP3/Ogg Vorbis/WMA/AAC/MIDI audio decoder and IMA ADPCM/Vorbis audio encoder user-loadableOgg, support CD-audio

Frequency playback and recording, the chip contains a high-performance, low-power DSP processor core VS_DSP containing 16 KB instruction RAM and RAM 0.5 KB of data.

VSl053B internal has 1 serial control and data input/output interfaces, 8 GPIO interfaces, high-performance variable sampling rate of ADC, DAC and stereo audio input interface and stereo audio output interface. PL2303 USB to achieve with standard RS 232 serial port, 2 separate large buffer for 2 bus connections, large data buffer used for USB bulk data transfers, automatic handshake mode can be used for serial communication, so that you can achieve much more than standard UART baud rate of the controller. PL2303 USB power management and remote wake-up agreement. The design, the PL2303 chipset is mainly used in the control unit and the power supply module download lines into one, greatly simplifies system design complexity, NOKlA 5llO LCD monitor for traditional matrix LCD, built-in English and Chinese character fonts, so NOKIA 5llO LCD display of the process, the need for single-chip reads from memory to the ASCII code value converted to the corresponding English and Chinese characters dot matrix information, and then through the serial port to dot matrix information transmitted to the LCD monitor in the display.

1.2 hardware design diagrams

The hardware system is mainly composed of the master module and a smart extension interface, audio coding/decoding module, LCD display module, keyboard LED indicates that the module, JTAG/ISP/RS 232 download interface, logical connection diagram shown in Figure 1.

1.3 interface design

1.3.1 VSl053B and keyboard and LCD display interface design

KEYl ~ KEY7 as system keyboard control unit corresponds to the function as shown in table 1.

Corresponding key LEDl ~ LED7, such as the press led KEYl is pressed, the LEDl lights. Peripheral interface as shown in Figure 2.

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