Why is Apple's fast charging data line so expensive?
USB B interface has various shapes, but in fact, it supports few protocols. Many users have formed the inherent impression that a shape of interface corresponds to a protocol.
But in fact, no matter USB 2 or USB 3 protocol, in addition to the common type-A, micro-b and type-C interfaces, there are many interfaces that are not often contacted, and the shape of the type-A ports of the two protocols is almost the same. Therefore, the shape of USB interface has nothing to do with the protocol it supports.
USB type-C is just an interface form and cable specification. The protocol behind it may be USB 3 protocol, USB 2 protocol, or even thunderbolt 3 and future USB 4 protocol.
The main purpose of USB protocol is to transmit data. The essential difference brought by different USB standards is the transmission rate. Generally speaking, in the same series of naming, the larger the number, the faster the transmission of numbers.
The USB type-C interface can also be used for display transmission. Due to the large number of pins, it can enter alt mode to transmit the display image.
However, not all usb-c devices support alt mode, image transmission is only an option for major manufacturers, so it is necessary to know whether the cable supports it when purchasing the device.
USB also supports the transmission protocol for audio, which is convenient for devices like microphone, speaker, headset and telephone to transfer audio stream directly to other devices by using analog signal, and even can be used across platforms without any driver.
In addition, with the help of USB type-C, the player can directly transmit the digital signal of audio information to the supported audio output devices such as headphones, so as to ensure the minimum interference in the transmission process. In daily use, you may need to pay attention to the specific audio protocol used in the output of the device. If the device only supports digital mode output audio devices, then the adapter must have a digital to analog converter and an operational amplifier, otherwise you will not hear any sound.
In order to ensure the maximum compatibility, usb-if stipulates that the headset with USB type-C interface as input must support both digital audio mode and audio adapter mode.
The standard power supply protocol of USB itself is now incorporated into USB power delivery. At present, USB power delivery has been updated to 3.0 protocol, which supports four voltage levels of 5V, 9V, 15V and 20V, with a maximum power output of 100W.