The USB3.0 root hub provides multiple USB 3.0 interfaces for expanding a certain number of host USB ports, which can be connected to the host through the downstream ports of USB devices (including functional devices and other hubs).
USB3.0HUB is commonly known as usb3.0 splitter, also known as usb3.0 hub. USB 3.0 is relative to usb2.0. The maximum transmission rate of USB2.0 is 480Mbps, which is 60mb/s.
The USB3.0 interface has a transmission protocol.
USB bus protocol:
The USB (Universal Serial Bus) bus protocol is a serial interface standard developed by seven companies including Intel, Compaq, Microsoft, IBM, DEC, Northern Telecom and Japan's NEC.
The USB bus is a polling bus, and the host control port initiates all data transfers. Each bus action transmits up to three packets, including token, data and handshake.
According to the pre-transmission principle, at the beginning of each transmission, the host sends a USB data packet describing the type, direction, USB device address and terminal number of the transmission action. Such packets are often called token packets. The USB device fetches its own data from the appropriate location in the decoded packet. The direction of data transfer is either from the host to the device or from the device to the host.
At the beginning of the transmission, the direction of data transmission is marked by a flag packet, and then the sender starts sending packets containing information or indicating that there is no data transmission. The receiver should also send a handshake packet to indicate whether the transfer was successful. USB data transfer between sender and receiver, host port and device can be considered as a channel. There is a special channel in USB - the default control channel, which is a message channel. It exists as soon as the device is started, providing an entrance for device settings, status query, and input control information.
USB contains four basic data transfer types:
Transmission control: used to set the device when the device is connected, and can also control the specified device.
Transmitting large amounts of generated and used batch data, with a large dynamic range under transmission constraints.
Interrupt 3360 is used to describe or match people's feelings or feedback in response to features.
Sync: Fills the predetermined USB bandwidth with the predetermined transmission delay.
Standard recipe:
transfer speed
The actual transmission rate of this new ultra-high-speed interface is approximately 3.2Gbps (ie 320MB/S). The theoretical maximum rate is 5.0Gbps (ie 640MB/S).
data transmission
USB3.0 introduces full-duplex data transmission. Two of the five wires are used to send data, the other two are used to receive data, and the other is a ground wire. In other words, USB 3.0 can read and write simultaneously at full speed. Previous USB versions did not support full-duplex data transfer.
power supply
The USB3.0 standard requires that the power capacity of the USB 3.0 interface is 1A, while the power capacity of USB 2.0 is 0.5A.
Power management
USB 3.0 does not use device polling, but uses an interrupt-driven protocol. Therefore, the standby device consumes no power until an interrupt occurs requesting data transfer. In short, USB 3.0 supports standby, hibernate and suspend states.
