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USB based MPEG -based video card Design and Implementation circuit

Published on Aug 10 2010 // USB based circuits

USB based MPEG -based video card Design and Implementation circuits


USB based MPEG -based video card Design and Implementation circuit 1

Abstract : This paper describes a USB2.0 interface based on the design of MPEG video card and its hardware and software design . Keywords : USB; video card ; MPEG; WDM Universal Serial Bus (Universal Serial Bus, or USB) Plug and Play and hot swap of its convenient features , and high transmission rate , a widely used PC in the field of peripheral connectivity standard . At present, widely used at home and abroad is USB1.1 specification , it supports two transmission rate : 1.5Mbps and 12Mbps, mainly used in low-speed transmission is a requirement . USB2.0 specification published in 2000 provided a 480Mbs transfer rate to meet demands for faster data transfer . In order for MPEG video card to the PC, fast transmission of large amounts of data, we designed the MPEG video card and PC- interface with USB2.0 technology . Design and development of the USB , we are the company based CYPRESS EZ-USB FX2 and FX2 series CY7C68013 chip development kits . 1, the hardware design The traditional PCI interface with MPEG video cards, not only occupy a limited PCI slot , install the inconvenience, and does not support hot swap and plug and play . Therefore, in this design , we use USB2.0 interface chip on the traditional MPEG video card is improved. Improved USB2.0 interface program shown in Figure 1 . The USB2.0 interface MPEG video card works : audio and video signals by AK4550 audio processing chip and AA7113 video processing chip A / D conversion, the analog signal into a PCM format 8bit digital signal , the incoming sound SZ1510 Capture video compression chip for processing , the code modulation PCM format data into line with the mixed format MPEG-1 video file , the final MPEG-1 data sent to PC via USB interface chip machine for further processing , such as storage , display . Design, we use the USB interface chip is the EZ-USB FX2 CY7C68013 series chips . The chip is for USB2.0 , and USB1.1 compatible and it supports two transfer rate : full speed (Full_speed) 12Mbps and high-speed (High_speed) 480Mbps, it does not support low-speed (Low_speed) 1.5Mbps. The chip ‘s internal structure shown in Figure 2 . CY7C68013-128AC integrated within an enhanced 8051 core , both with the standard 8051 compatible , there are a number of improvements : a maximum operating frequency 48MHZ, one instruction cycle only four clock cycles than the standard 8051 was increased by 2.5 times ; 2 UARTS ports ; three timer / counter ; extended interrupt system and its additional I / O port and so on . CY7C68013 ‘s internal integrated USB2.0 USB2.0 SIE to complete most of the processing agreement , reducing the user on the complexity of the USB protocol handling . In addition , users in the development , you can use GPIF and the FIFO method and high-speed peripheral devices to achieve logical connections, and high-speed data transmission. In the improved scheme , we use the GPIF way communication between the implementation and Z1510 . 2, software design USB software design consists of three areas: the firmware (Fireware) design , driver design and the design of the host -side applications . (1 ) firmware design Design, we consider the MPEG video cards may require rapid transmission of large amounts of data continuously , and data integrity requirements are not too high , we are using ISO transmission . In addition, we work to CY7C68013 GPIF mode FIFO Read mode , can transfer up to 4G byte (WORDWIDE = 0) or word (WORDWIDE = 1). Peripheral data do not require a 8051 deal , the way we use automatic packaging (AUTOIN = 1), directly from the FIFO to the SIE, it will help improve transfer rates. The main implementation code as follows : void TD_Init( ) { CPUCS = 0X01; file://CLKSPD[1:0]=10; for 48MHz operation. GpifInit( ); …… SYNCDELAY; EP6CFG = 0XDA; file: / / endpoint configuration : Synchronization IN mode , the buffer size of 1024 bytes SYNCDELAY; FIFORESET = 0X80; // activate NAK_ALL to avoid race conditions SYNCDELAY; FIFORESET = 0X06; file://reset, FIFO 6 SYNCDELAY; FIFORESET = 0x00 ; file : / / deactivate NAK_ALL SYNCDELAY; EP6FIFOCFG = 0X0D; file://wordwide=1 SYNCDELAY; …… } (2 ) Driver In the WINDOWS platform , USB driver consists of three parts : USB device driver , USB bus driver and the USB host controller driver, they must follow the WIN32 Driver Model (WDM). Which , WINDOWS operating system has provided at the end of the USB driver stack bus driver and the USB host controller driver. The USB device driver developers to write by the device , it is through the USB bus driver to send a URB (USB Request Block) of the IRP (I / O Request Packet), to achieve the exchange of information between the USB peripherals . When the host application to be on the USB device I / O operation, it calls the Windows API function calls Win32 Win32 subsystem , the I / O Manager to request this construct into an appropriate IRP, and pass it to the USB Device driver . USB device driver receives the IRP , the IRP contains according to the specific operation code structure to respond to the URB and put it in a new IRP and then passes the IRP to the USB bus driver , USB bus driver under the IRP URB contained in the implementation of response operations , and return the result of the operation through the IRP to USB device drivers . USB device driver receiving this IRP , it will return the operating results through the IRP I / O Manager. Finally , I / O manager in this IRP operating results returned to the application , thus the application on a USB device I / O operation is complete . USB device driver development , the company’s development kit can be used Numega Driver Works and Microsoft Corporation 2000DDK, and to VC + +6.0 as a supplementary development environment. Driver Works to provide the driving guide , according to the needs of users , automatically generate code framework . Reduce the difficulty of development and shorten the development cycle. Companies in the CYPRESS EZ-USB FX2 Development Kit , there is a generic driver, the program without modification by the DDK compiled directly . In this design, due to time , we have adopted is the generic driver (GPD). (3 ) Application Programming USB host application is a computer program to complete a specific function , the key is read from a USB peripheral or send a specific amount of??, USB standard device request and specific orders . In addition , you can do further processing of data , such as: storage , display, fast Fourier transform . In the WINDOWS 2000 , we are using application development tools are VC + +6.0. 3, Conclusion The card is a conventional MPEG video card PCI interface improvements , it supports hot swap and plug and play . As a result of USB2.0 interface, transfer rate is also higher than the latter, to meet the requirements of high-speed transmission of data to solve the existing USB1.1 transmission bottlenecks . We believe that with the major motherboard supplier to the USB2.0 support , USB2.0 PC- bound applications in widely used in various fields .