USB Type-C
Usbtype-c is A new form of USB interface (USB interface as well as type A and type B), which is introduced with the latest USB3.1 standard. Released by usb-if in August 2014, it is a new interface developed by USB standardization organization to solve the defects of USB interface, such as non-uniform physical interface specification and one-way transmission of power. It integrates charging, display, data transfer and other functions.
The most important feature of the c-type interface is that it supports insertion in both positive and negative directions, which officially solves the worldwide problem of "USB never inserts "and inserts both positive and negative sides at will.
Various IT and 3C devices vary by design power, input and output voltages, interfaces, and jack apertures; Their exclusive power/charging accessories, sizes, wire lengths and transformer sizes vary; This leads to continuous carrying and waste of equipment and eliminates environmental protection problems. In 2011, the European Union and China legislated to unify the charging standard of mobile phones, taking micro-usb as the only charging standard. In 2012, the usb-if association also introduced the charging/power specification for PowerDelivery(PD)1. 0 is based on USB, while in 2014 usb-if released revolutionary type-c1. 0 interface standard and USBPD 2. The 0 standard is based on the usbtype-c interface standard, revolutionizing new devices in the USB interface and future power transmission.
To understand the principle of type-c, you first need to understand its PIN definition. As shown in figure 1, port type-c has four pairs of TX/RX difference lines, two pairs of USBD+/D-, one pair of SBU, 2 CC, four VBUS and four ground wires.
Under normal circumstances, USB3.1 only USES two pairs of TX/RX difference lines as the data line, which are connected to TX2/RX2 when connected to TX1/RX1. As you can see, in any case, there are two pairs of unused difference lines. The DP alternate mode loads the DP signal into two pairs of "redundant" difference lines so that the USB3.1+DP can work simultaneously.
Of course, if the receiver only need DP signal, don't need USB3.1 signal, the DP can use all 4 of TX/RX difference line output, so as to realize the DP output of up to four lanes, provided the total output of up to 32.4 Gbps bandwidth (each lane can output 8. IGbps), 5 kx3k60 auxiliary video easily, even up to 8 k x 4 k60 frame video (4:2:0 data), the pattern is DPonly mode, in addition to compatible with usb, Type-c also retains the USBD+/D- signal for USB2.0 devices, so just switch to the type-c interface, and USB2.0 or even USB1.0 devices can support both front and back ports. It is worth mentioning that the DP+USB2.0 mode can be realized by using USBD+/D- in conjunction with the above DPonly mode. DP occupies 4 pairs of TX/RX difference lines, while USB only USES D+/D-.
Figure 1 shows that type-c also provides two CC lines and two SBU lines. CCline is mainly used for the communication of the PowerDelivery module. CCline is first used to insert the direction of the interrupter: if inserted, the host USES CC1 to communicate with the device. CC2, it can be seen that CC USES the single-line protocol. When the SBU function is opened, it is embodied as the aux_P/aux_N difference line in the DP protocol. Responsible for transmitting DPCD, EDID and other key information of the equipment.
The five main features of the C type make usbtype-c a flexible and extensible interface.
The usbtype-c interface's default 5V power supply is backwards compatible with the previous USB interface. Not only that, the new usbtype-c interface contains four pins specifically for power supply and grounding. USB power supply specifications allows USBType - C interface support and 5 a current up to 20 v voltage.
The usbtype-c interface is symmetric, so its insertion and cable direction are both positive and negative. The release of the insertion direction resolves the main fault caused by the front interface. Previous interface types predicted the capabilities of the auxiliary device. The usbtype-c interface can access either end of the two ends, and the function is defined by the hardware being accessed. The interfaces at both ends of the usbtype-c cable are the same, so cable insertion is simplified.
Usbtype-c supports USB2.0, USB3.1Genl and USB3.1Gen2 data transfer rates. USB2.0 and USB3.1 are defined by separate specifications. The SuperSpeedUSB differential signal pair is allocated on both sides of the interface, so a set of SuperSpeedUSB signal transmission connections are used when inserting the interface in either direction.
The usbtype-c interface contains two channels for configuring the signal pins for function negotiation. This signal determines the insertion direction of the interface and is used to negotiate the power function, alternative mode, and peripheral mode on the interface.
The usbtype-c interface supports various OEM product customization patterns to extend device functionality. Signal redistribution is achieved through negotiation on CC channel. The interface can be divided into peripheral mode and alternative mode. To go into peripheral mode, perform a simple logical check on the CC channel to determine which peripheral mode is required. To enter the alternative mode, the link will be properly set up using BiphaseMarkCode two-way communication on the CC channel. During this negotiation, the two devices need to agree on the redistribution of signals before any changes can be made. All usbtype-c interfaces need to be used as usb-compatible interfaces in non-alternate or non-peripheral modes.
The characteristics of c-type hardware interface are obvious, mainly including the following points:
(1) support positive and negative symmetric interpolation to solve the problem that inverse interpolation cannot be inserted in practical applications;
(2) thin interface, which can support thinner devices, which can make the design of portable devices thinner and thinner;
(3) support greater power transmission, up to 100 watts, support more high-power load equipment.
(4) flexibility to support single-port and dual-port C applications.
(5) support two-way power transmission, transformation and reception.
USB" means "universal serial bus". This is a new interface technology, applied to the PC field. "As early as 1995, there were PCS with USB ports, but their USB interfaces were idle due to the lack of hardware and software support," he said. After 1998, with the increasing number of USB interface support modules and USB devices built into Windows 98 by Microsoft, USB interface gradually entered the practical stage. With the popularity of a large number of personal computers that support USB, USB has gradually become the standard interface for PCS and become the general trend. On the host side, the latest PCS support USB; Almost 100%, and the number of devices using USB ports on the peripheral side is also increasing, such as keyboards, mice, cameras, scanners, printers, modems, digital cameras, joysticks, TVS, flash drives, hard drives, and even sound CARDS, speakers, phone chargers, network CARDS, etc.
(1) it can be hot-plugged. This allows the user to use an external device without having to repeat the "close the parallel port or serial cable to start again" action, but you can plug in the USB cable directly under PC boot.
(2) easy to carry, most USB devices are "small, light and thin". For users, a USB hard drive is half as light as an IDE hard drive. Of course, when you want to carry around a lot of data, a USB hard drive will be your first choice.
(3) unified standards. General is the hard disk of IDE interface, mouse keyboard of serial port and printer scanner of parallel port. However, with USB, when you have a USB hard drive, a USB mouse, a USB printer, etc., all these application peripherals can be connected to the PC using the same standard.
(4) multiple devices can be connected. USB usually has multiple ports on a PC and can be connected to multiple devices at the same time. If you connect to a four-port USBHUB, you can connect to four other USB devices, etc., and connect these devices to your PC at the same time without any problems (note: up to 127 devices).
(5) no external power supply is required. USB provides a built-in power supply that provides 5V power for low-voltage devices, eliminating the need for additional power for new peripherals. Taking advantage of this feature, some manufacturers have also developed appropriate wiring to use USB as a power outlet, for example as a charger for a mobile phone, or as a source of power for small electric lights, regardless of the primary purpose originally used to connect to a computer.
(5) low cost. USB interface circuit is simple and easy to implement, especially for low speed devices. USB system interfaces/cables are also relatively simple and cost less than serial/parallel ports.
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