The usb hub is also called the USB Hub, a device that can extend a USB interface to multiple (usually four) and can use these interfaces simultaneously. To plug one of the computer chassis or other power supply equipment, U disk, USB data cable and then plugged into the usb hub on the line. usb hub mainly used as an extension USB interface; multi-card reader, although there are USB interface, USB Hub but the main function is to provide a number of different memory card interface.
usb hub can be connected with computer desk lamp, computer fan, MP3, U disk, recording pen, digital camera, etc.
* A USB interface can be extended into a number of independent working USB interface, each power supply up to 500MA
* Adoption of second generation USB HUB controller
* Directly connected with the computer, no external power supply, simple and easy to use
* Computer automatically identify the installation, no driver, plug and play, plug freely
* Support USB2.0, speed up to 480Mbps, backward compatible with USB1.1
* Built-in current overload short-circuit protection device
* System support: Win95 / 98 / Me / 2000 / XP, Linux2.4andMac os8.5 or above
The usb hub provides an electronic interface between the USB device and the host. The usb hub consists of a usb hub forwarding repeater and a usb hub controller. The usb hub forwarding repeater is responsible for connecting the work. It also supports exception handling such as bus error detection and recovery, USB Hub connection and no connection detection. The usb hub controller provides host-to-usb hubs for communication mechanisms. The usb hub specific status and control commands allow the host to configure the usb hub and monitor and control each of its downstream ports.
The usb hubs exhibit different connection behavior depending on whether they are in the transport packet, the wake-up signal, or the idle state. First, the packet signal connection. Packet signal connection is divided into two kinds of uplink and downlink connections. The uplink connection is host-oriented. USB Hub When an enabled downstream port detects an SOP, it establishes an upstream connection to an upstream port rather than any other downstream port. The downstream connection is device oriented. When the usb hub detects the SOP on the upstream port, USB Hub it establishes a connection to all enabled downstream ports. Ports that are not in the enabled state can not be transmitted in the downstream direction. usb hub also has no connection to the idle state. In the idle state, all ports of the usb hub are in receive mode and wait for the start of the next packet. Second, wake up connection. The suspended usb hub sends the wake-up signal received by the upstream port to all enabled downstream ports. USB Hub When a suspended usb hub is detected to cause a local call or enable a wake-up signal from the downstream port, the wake-up signal is reflected to the upstream port and all enabled downstream ports, including itself. The wake-up signal is not reflected to an un-enabled or pending downstream port. There will be more discussion later.
The usb hub is a very important USB component for establishing connections between the host and the device. It is important to detect and prevent any errors, especially those that can lead to deadlocks. USB Hub The usb hub must handle connection errors in forwarding mode. The usb hub must also be able to detect and recover packets sent to the usb hub controller.