Standard
USB On-The-Go
The USB Implementers Forum (USB-IF) is responsible for the development of the USB standard. Its members include: Apple Computer, Hewlett-Packard, NEC, Microsoft, and Intel.
At the end of 2001, the USB-IF announced the USB 2.0 specification. Like the previous USB 0.9, USB 1.0, and USB 1.1, the specification is fully backward compatible. Subsequently, USB-IF announced USB On-The-Go (USB OTG, current version: 1.0a) as a complementary standard to the USB 2.0 specification, making it possible to directly exchange data between portable devices.
The USB connector is divided into two types, A and B, which are used for the host and the device respectively. The miniaturized connectors are Mini-A and Mini-B, and Mini-AB (which can support both Mini-A and The socket of Mini-B).
technical details
Currently, USB supports three kinds of data signal rates, and the USB device should correctly indicate the rate of its use on its housing or sometimes on its own. The USB-IF performs device authentication and provides basic rate (low-speed and full-speed) and high-speed special trademark licenses for devices that pass compatibility tests and pay a license fee.
1.5 Mbps low speed rate. It is mainly used for human interface devices (HID) such as keyboards, mice, joysticks, and the like.
12 Mbps full speed rate. Prior to USB 2.0, which was once the highest speed, the higher speed high speed interface from the back should be compatible with the full speed rate. Bandwidth can be divided between multiple full-speed devices on a first-come, first-served basis; it is not uncommon to use more than one isochronous device to exceed the upper bandwidth limit. All USB ports support full speed.
High speed rate of 480 Mbps. Not all USB 2.0 devices are high speed. High speed devices should be compatible with full speed when plugged into a full speed port. The high-speed port has a Transaction Translator function that is capable of isolating the data flow between full-speed and low-speed devices and high-speed, but does not affect the power supply and serial depth.
Ultra-high speed of 5Gbps. Compared to the highest theoretical speed of 480Mbps for existing USB 2.0, USB 3.0 can support up to 5.0Gbps, which is 10 times that of USB 2.0. If USB 3.0 is applied to a storage device such as an external hard disk, a pen drive, or a Blu-Ray burner, the data transfer time can be greatly reduced.
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Post time: Apr-10-2018