The Implementation And Optimization Of USB Data Communication On Embedded Platform Based On Intel Xscale Processor

Handheld embedded devices have been making great progress in recent years. Their ability to communicate with other devices is more emphasized than before. Compared with other data transfer technologies, the Universal Serial Bus (USB) seems to be more popular. Announced in 1994, USB has become the standard peripheral interface of PC. Now we have the new version, USB 2.0, with a transfer rate of 480Mbps.At the speed of 12Mbps of USB 1.1, it is insufferable to transport data between PC and a handheld device with large storage. So it is necessary to provide devices with USB 2.0 interface. There are many situations in which we have to transfer data between embedded devices without participance of PC, and for this reason, devices with USB host ability are developed.Aim of this research is to implement USB 2.0 device and USB 1.1 host on our handheld platform. This platform has an Intel PXA270 processor core, with a lot of peripherals, such as USB device controller and hard disk. OS of this platform is Microsoft WinCE 5.0.We use Netchip NET2272 as USB 2.0 device controller and designed its hardware schematic. USB device driver and Mass Storage device driver make up the software part of our USB device. Device driver for NET2272 focuses on bus configuration and USB data transfers, while Mass Storage device driver makes us a "mobile hard disk" to PC host.USB 1.1 host controller integrated in PXA270 is the hardware basis of our USB host and also, we used a power chip to manage USB power supply. Host software is divided into three categories, the OHCI compliant host controller driver, the USB system driver, and the Mass Storage client driver.After realizing basic functions, we optimized our platform in transfer rate and power consumption, and made some tests.