USB interface development process
USB2.0 specification is evolved from the USB1.1 specification. Its transfer rate reached 480Mbps, converted to MB 60MB / s, enough to meet the requirements of most peripherals. The Enhanced Host Controller Interface (EHCI) in USB 2.0 defines a architecture that is compatible with USB 1.1. It can drive USB 1.1 devices with USB 2.0 drivers. In other words, all devices that support USB 1.1 can be used directly on the USB 2.0 interface without worrying about compatibility issues, and attachments like USB cable, plug, and so on can also be used directly.
The use of USB for the printer application is a significant increase in speed, USB interface provides a 12Mbps connection speed, compared to the parallel port speed increase of more than 10 times, at this speed under the print file transfer time greatly reduced. USB 2.0 standard to further increase the interface speed to 480Mbps, 20 times the speed of ordinary USB, more significantly reduce the print file transfer time.
USB 3.0Promoter Group, comprised of Intel, Microsoft, Hewlett-Packard, Texas Instruments, NEC, ST-NXP and other industry giants, announced that the organization's new generation of USB 3.0 standards has been officially completed and publicly available. USB 3.0 theoretical speed of 5.0Gb / s, in fact, can only reach the theoretical value of 5 percent, it is close to USB 2.0 10 times. USB3.0 physical layer using 8b / 10b encoding, so that the theoretical speed will be 4Gb / s, the actual speed but also deduct the cost of the agreement, in the 4Gb / s basis to be less. Can be widely used in PC peripherals and consumer electronics products.
USB 3.0 will be referred to as "USB SuperSpeed" in actual device applications, conforming to previous USB 1.1 FullSpeed and USB 2.0 HighSpeed. Business controllers that are expected to support the new specification will be available in the second half of 2009, with consumer products already on the market.