Why you need a USB controller

Universal USB buses are a popular interface for a personal computer. They allow the serial connection of various devices up to 127 units. Universal USB-bus supports the function of connecting / disconnecting devices without turning off the power of the personal computer. In this case, the connected devices can be powered directly through the USB interface, which eliminates the need to use additional power supplies. This article will discuss a device such as a USB-controller. We will review its purpose, specifications and types.

Why do I need a USB controller?

This device provides communication of all peripheral devices connected to the bus. USB-controller is an intelligent device that is able to interact around the CPU with the RAM of the personal computer in the mode of through access to memory. By the type of integration, such devices can be used in the system logic or in the form of separate chips (chips) both on the motherboard of the computer itself and on the external boards (expansion card). Using the PCI connection method, the USB controller can be configured for PCI and PCI Express buses.

Specifications and types of devices

For specification USB1.1 two types of such devices are developed. So for USB1.0, Intel developed USB-controllers such as UHCI and OHCI. The difference between these devices is only in the method of access to registers. In the first case, the registers are structurally located in the space of the system ports responsible for information I / O, and in the second case they are located in the memory section of the personal computer. USB controller type OHCI is considered more intelligent than the type of UHCI. This advantage lies in its ability 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, a Universal Serial Bus controller type EHCI has been developed. It is capable of supporting work at high speeds (480 Mbit / s). In this controller, thanks to a split transaction, the low-speed USB1.1 interface is supported to support slower devices.

For USB3.0, a high-speed USB HOST controller type XHCI is designed, which is capable of supporting information exchange at all three speeds.

Conclusion

To sum it up, let's say that if your computer does not have USB ports, then thanks to a minor upgrade to it, you can install a USB-controller. Such devices are implemented in the form of PCI-type expansion cards or PC-cards for laptops. Remote controllers are available with support for USB1.0, 2.0 and 3.0. If you decide to install such a device, it is better to choose a faster one, since their cost is almost the same. By this principle, you can replace an existing controller with a faster one. However, with this upgrade, we should not forget that for the full operation of the device you will need to reinstall the drivers for this controller.