Universal Serial Buses USB is a fairly 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 is not necessary. The connected devices can be powered directly via the USB bus, which eliminates the need for additional power supplies. Today we’ll talk about such a scheme as a universal serial bus USB controller. We will consider its purpose and the types that exist today.
Why do I need a universal serial bus USB controller?
These devices are part of the computer platform, providing the message of external devices connected to the USB-bus. The universal USB serial bus controller is an intelligent device that can interact, bypassing the central processor, with the computer's RAM in end-to-end 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 card). By the method of connection, the controllers of the universal USB serial bus are distinguished into devices for PCI buses and for PCI Express buses.
Specifications and types of USB controllers
For the USB1.1 specification, there are two types of implementations of such devices. For example, for USB1.0, Intel has developed two types of USB serial bus controller - UHCI and OHCI. Their difference lies only in the method of access to the registers: the registers of the first type are structurally located in the space of system ports responsible for input-output of information, and the logic circuits of the second type are located in the memory space of a personal computer. Note that a USB OHCI controller is considered more intelligent than UHCI, since it can free the main processor from the need to perform routine operations related to transferring data via USB buses. Both controllers use 32-bit addressing.
For USB2.0, a universal USB serial bus controller of the EHCI type has been developed, which is capable of supporting operation at high speeds (480 Mbps). Thanks to the split transaction, it supports the low-speed USB1.1 interface, which is very important for slower devices.
USB3.0 needs a universal controller like XHCI. He is able to maintain the exchange of information at any speed.
Conclusion
So, if you are the owner of an old computer that does not have USB ports, do not worry: through a minor upgrade, you can install a USB controller. Such devices are implemented in the form of a PCI-type expansion card or PC-cards for laptops. These controllers come with support for USB1.0, 2.0, and 3.0. If you decide to install one of these devices for yourself, opt for a faster one, fortunately, their cost is almost the same. Another example: if only USB versions 1.0 or 1.1 are supported on your PC, you can install a controller that will provide version 3.0.