Characteristics of USB interface

Usb has the following notable features.

(1) high-speed data transmission

Usb 1. 1+0 supports the transmission rate of 1.5 ~ 12 Mbps, and version 2.0 supports the transmission rate as high as 120 ~ 240 Mbps, which is nearly 10 times faster than a standard parallel port.

(2) High degree of freedom connection/topological structure

The expansion interface can support as many as 127 devices on a computer at the same time, without occupying pc hardware resources (such as I/O address, memory, interrupt, dma, etc.). ). The tree topology structure is adopted between the master port and the usb slave port, which makes the expansion of peripherals more free.

(3) live plug/plug and play

The usb method realizes the expansion method of plug and play (hot plug) peripherals. All usb devices support hot plug, the system is automatically configured, and jumper and dip switch settings are completely abandoned.

(4) Built-in power supply

Usb power supply can provide 5v and 500ma (maximum) power supply for low-voltage equipment. Therefore, for the low-power input devices used, there is no need to use a separate power supply, which can reduce the cost of these devices and improve the cost performance.

(5) Support multiple transmission modes.

Usb provides four transmission modes to adapt to different transmission purposes and has strong versatility.

It is precisely because of the above outstanding characteristics that usb devices have been widely used in the expansion of arm embedded peripherals.