First, HDMI supports the principle of hot swapping
Now home theater equipment are through the HDMI interface for the next generation of audio and video transmission, HDMI Chinese called high definition multimedia interface, is a high-speed digital image and sound transmission interface, which means that only one line can transmit high-definition video signals and audio signals at the same time, and is uncompressed. Conform to the current and future high-definition video transmission needs, so it is more and more widely supported, including televisions, computers, tablets and even mobile phones, including devices, have corresponding HDMI interfaces.
But the increasing presence means that the likelihood of problems is also increasing. On the one hand, from time to time there will be events about HDMI hot plug burned interface chips, on the other hand, many users have been hot-swappable HDMI interface, dozens or even hundreds of times have not had problems, then the controversy comes, HDMI interface can not be hot plugged in the end?
Does HDMI theory support hot swapping?
HDMI has evolved in about 10 versions so far, with HDMI version 1.4a published in 2010 and the latest version now HDMI 2.1. You may not believe it, but HDMI has been designed to be hot-swappable since its inception. That is to say, the HDMI interface supports hot plugging regardless of which version. (Another saying is that version 1.2 is supported, but the number of devices before version 1.2 is not much on the market, right?)
The principle of hot swapping
In the 19th pin of the HDMI mother, a half-cut pin is placed, called hot plug monitor pin (Hot Plug Detect), when the HDMI is unplugged, the hot-swappable monitor pin is disconnected first, and then the HDMI circuit detects the disconnection, notifies the input and output device, stops working, and plays the role of hot plugging. According to the different length of the interface pin to achieve the principle of hot swapping, and USB hot swap is a little similar. There are four gold fingers inside the USB interface, the longer two are power supply, priority is given to ensure power when plugging and unplugging, and then data exchange, to ensure that hot plugging does not damage the device data.
Is there a difference in the interface?
The current HDMI interface has four types, A type (standard) width 13.9mm, generally suitable for HDTV, TV, set-top box, Blu-ray DVD and other devices; Type C (Mini) width 10.42mm, generally suitable for MP4; Video cameras, tablet computers and other digital products; D-type (Micro) width 6.4mm, generally suitable for smart phones, tablet computers; In addition, there is a B-type interface, but only as a standard, not used in any products. A, C, D these three interfaces have a hot-swappable monitoring pin, so they are all hot-swappable.
Second, the real cause of HDMI hot swap damage
Or did some netizens plug it in?
Although HDMI theoretically supports hot swapping, we still hear some hot-swappable HDMI lines in life caused by interface and even electrical damage. And some manufacturers also clearly state in the product description: the HDMI cable must be plugged and removed when the product is powered off. Aren’t these contradictory to the “theoretically supported” hot plug above?
Theory belongs to theory, and reality depends on the specific use environment, bad and not bad is not absolute, but the probability is high. Generally speaking, if there are the following two cases, hot-swappable HDMI is more likely to cause damage to the interface chip.
1, the quality of the wire is poor:
The HDMI line on the market can be described as a mixture of fish and dragons, the quality is uneven, and the price ranges from a few yuan to a few hundred yuan. Some consumers feel that the connection line is a small thing, do not have to think too much about quality, so they only pay attention to the price. The insulation of poor quality wires may not be done well enough, and short circuits may occur. If the connector is not plated, it is easy to rust and cause physical damage to the interface. In addition, the conductivity and anti-interference ability of the wire will be relatively low.
2. Hazards caused by static electricity:
Static electricity can be said to be the invisible killer of all electrical appliances. Because HDMI is a very high-speed digital signal, in the design of the transmission and reception chip, the use of antistatic protection circuits generally can only withstand 5-8 kV electrostatic voltage, but in real life, if the environment is dry, and at the same time there are conditions for generating electrostatic voltage, it is possible to generate tens of thousands of volts of electrostatic voltage is common, in the design of the source and display end, generally will sacrifice some capacitance margin and configure ESD protection circuit. However, some machines do not have ESD protection circuitry in order to save costs, and may burn the chip when the electrostatic HDMI line is inserted.
On the other hand, our power outlet may be 2-pin and there is no ground wire. For some families, even three-phase sockets, the ground wire is not grounded. When the general user installs the LCD TV and the projector, there will be no additional grounding wire, which is easier to form static electricity.
Summary: In fact, many hot-swappable operations cause burnout interface accidents are not necessarily HDMI interfaces. As we all know, USB is hot-swappable, but we will still hear that so-and-so’s computer plugged in the U disk and the result burned the motherboard, which is likely to be the problem of the U disk. In addition, the VGA interface burns down. Therefore, in order to ensure the normal daily use of electrical appliances, in addition to understanding the characteristics of the product itself, the specific situation of the specific analysis, but also to see the wire, it is recommended that you try to buy high-quality, reliable performance HDMI line.
Post time: Sep-29-2022