USB interface ] OHCI, UHCI, EHCI and XHCI controllers

 

(1) OHCI (Open Host Controller Interface)

is a standard that supports USB 1.1, but it is not only for USB,

Other interfaces are also supported, such as Apple's Firewire (IEEE 1394) interface. Compared with UHCI, OHCI hardware is complex and hardware does more things, so it is relatively simple to implement the corresponding software-driven tasks. Mainly used for non-x86 USB, such as expansion card, USB host control of embedded development board.

 

 

(2) UHCI (Universal Host Controller Interface)

is an interface standard for USB 1.0 and 1.1 that is dominated by Intel and is not compatible with OHCI. UHCI's software-driven tasks are heavy and need to be done more complex, but you can use a cheaper, simpler hardware USB controller. Intel and VIA use UHCI, while the remaining hardware providers use OHCI.

 

 

(3) EHCI (Enhanced Host Controller Interface)

is the interface standard of Intel's leading USB 2.0. EHCI only provides high-speed functions for USB 2.0, while relying on UHCI or OHCI to provide support for full-speed or low-speed devices.

 

 

(4) xHCI (eXtensible Host Controller Interface)

is the latest and most popular USB 3.0 interface standard. It has greatly improved speed, energy saving and virtualization compared with the previous three. xHCI supports all kinds of speed USB devices (USB 3.0 SuperSpeed, USB 2.0 Low-, Full-, and High-speed, USB 1.1 Low- and Full-speed). The purpose of xHCI is to replace the previous 3 (UHCI/OHCI/EHCI).

 

 

USB	Standard	Special feature	Using
OHCI	USB 1.1 but other interfaces are also supported.	- it is complex and does more things than UHCI. - relatively simple to implement the corresponding software-driven tasks.	- non-x86 - USB host control of embedded development board.
UHCI	USB 1.0 & USB 1.1 by intel. it is not compatible with OHCI.	- it is heavy and need to be done more complex. - but it can use a cheaper, simpler hardware USB controller.	- intel and VIA use UHCI
EHCI	USB 2.0 by intel	- only provieds high-speed functions for USB 2.0 - while relying on UHCI or OHCI to provide support for full-speed or low-speed devices.
xHCI	USB 3.0 is the latest and most popular interface.	- improve speed, energy saving and virtualization compared with the previous three. - support aloo kinds of speed USB devices (USB 3.0 SuperSpeed, USB 2.0 Low-, Full- and High-speed, USB1.1 Low- and Full speed)	- the purpose is replace the UHCI, OHCI and EHCI.

 

 

 

[USB speed]

    Low speed(초당 1.5 메가비트)
    Full speed(초당 12 메가비트)
    High speed(초당 480 메가비트)
    SuperSpeed(초당 5 기가비트)
    SuperSpeedPlus(초당 10 기가비트)

 

 

USB와 썬더볼트의 이동 속도 비교

 

 

USB Basics---Introduction to OHCI, UHCI, EHCI and XHCI Controllers - Programmer Sought

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