Universal Serial Bus Controller: Description and Purpose of the Logic IC
Universal serial USB buses arerather popular PC interface. With it, you can connect 127 different devices at the same time. They support the function of connecting / disconnecting devices, while turning off the computer there is no need. The connected devices can be powered directly via the USB bus, eliminating the need for additional power supplies. Today we will talk about such a scheme as a Universal Serial Bus controller USB. We will consider its purpose and existing types today.
What is the purpose of a Universal Serial Bus controller?
These devices are part of the platformcomputer, providing a message connected to the USB-bus external devices. Universal Serial Bus Controller USB is an intelligent device capable of interacting, bypassing the central processor, with the computer's RAM in the through access mode. By the type of integration, these devices can be used as part of the system logic or as a separate chip both on the motherboard itself and on the remote (expansion board). By the method of connection, Universal Serial Bus controllers differ in the devices for PCI buses and for PCI Express buses.
Specifications and types of USB-controllers
For USB1 specification.1 there are two types of implementation of such devices. For example, for USB1.0, Intel has developed a serial USB bus controller of two types - UHCI and OHCI. Their difference is only in the method of access to registers: registers of the first type are structurally located in the space of system ports responsible for input-output of information, and logical chips of the second type are located in the memory space of the personal computer. Note that the USB controller type OHCI is considered more intelligent than UHCI, since it is able to free the main processor from the need to perform routine operations associated with data transfer via USB buses. Both controllers use 32-bit addressing.
For USB2.0 developed the controller of universal serial USB bus type EHCI, which is capable of supporting work at high speeds (480 mbps). In it, thanks to the split transaction, support for the low-speed USB1.1 interface is implemented, which is very important for slower devices.
For USB3.0 you need a universal controller type XHCI. It is capable of supporting the exchange of information at any speed.
So, if you own the oldcomputer that does not have USB ports, do not worry: you can install a USB controller with a minor upgrade. Such devices are implemented in the form of PCI-type expansion cards or PC-cards for laptops. These controllers are available with support for USB1.0, 2.0 and 3.0. If you decide to install yourself one of these devices, stop your choice for a faster, better, their cost is almost the same. Another example: if on your PC only USB versions 1.0 or 1.1 are supported, you can install a controller that will provide version 3.0.