英文资料及翻译英文料及翻译.doc

英文资料及中文翻译 PDIUSBD12----USB interface device with parallel bus The PDIUSBD12 is a cost and feature optimized USB device. It is normally used in microcontroller based systems and communicates with the system microcontroller over the high-speed general purpose parallel interface. It also supports local DMA transfer.This modular approach to implementing a USB interface allows the designer to choose the optimum system microcontroller from the available wide variety. This flexibility cuts down the development time, risks, and costs by allowing the use of the existing architecture and minimize firmware investments.This results in the fastest way to develop the most cost effective USB peripheral solution.The PDIUSBD12 fully conforms to the USB specification Rev. 2.0 (basic speed). It is also designed to be compliant with most device class specifications: Imaging Class, Mass Storage Devices, Communication Devices, Printing Devices, and Human Interface Devices.Assuch, the PDIUSBD 12 is ideally suited for many peripherals like Printer, Scanner, External Mass Storage (Zip Drive), Digital Still Camera, etc. It offers an immediate cost reduction for applications that currently use SCSI implementations.The PDIUSBD12 low suspend power consumption along with the Lazy Clock output allowsfor easy implementation of equipment that is compliant to the ACPI(TM),OnNOW(TM), and USB power management requirements. The low operating power allows the implementation of bus powered peripherals. In addition; it also incorporates features like SoftConnect(TM), GoodLink(TM), programmable clock output, low frequency crystal oscillator, and integration of termination resistors. All of these features contribute to significant cost savings in the system implementation and at the same time ease the implementation of advanced USB functionality into the peripherals. 1. DMA transfer Direct Memory Address (DMA) allows an efficient transfer of a block of data between thehostandlocalsharedmemory.UsingaDMAco