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Frequently, netizens mention in their reviews that why this monitor doesn't have an HDMI interface? It seems that not having an HDMI interface is a major flaw of the monitor. So why is the HDMI interface so popular? It can be said that HDMI is one of the most common interfaces we see in our daily lives, and it is widely used in home multimedia devices.

On April 2002, seven companies including Hitachi, Panasonic, Philips, Silicon Image, Sony, Thomson, and Toshiba jointly established the HDMI High-Definition Multimedia Interface Organization, and began to work on formulating a new digital video/audio interface technology that meets the standards of the high-definition era. After more than half a year of preparation, the HDMI organization officially released the HDMI 1.0 standard on December 9, 2002, marking the official entry of HDMI technology into the historical stage.

High Definition Multimedia Interface (HDMI) is a digital video/audio interface technology, suitable for dedicated digital transmission of images. It can transmit both audio and video signals simultaneously, with a maximum data transfer speed of 2.25GB/s.

Features:

1. The latest HDMI 1.4 standard supports 4Kx2K resolution, has an Ethernet channel, audio return channel, supports 3D functions, etc. 2. Supports 4K resolution output, providing a foundation for the support of current 4K TVs and monitors. 3. Supports 3D functions, meeting the display signal transmission requirements of 3D TVs. 4. It can also support color gamut spaces above 30 bits, presenting the most realistic and vivid colors under various standards.

HDMI is a digital interface, and because all analog connections (such as component video or S-video) require no loss during conversion from analog to digital, it provides the best video quality. This difference is particularly noticeable at higher resolutions, such as 1080p. Digital video will be clearer than component video, eliminating the softness and trailing effects found in component video. Details like text, which are small and have high contrast, will maximize this difference. Additionally, there are many reasons why HDMI interfaces are widely used, which has also led to the development of various sizes of HDMI interfaces, mainly Micro, mini HDMI, and standard HDMI interfaces.

DisplayPort (DP):

The DP interface is the successor of DVI. The commonly seen ones now are the DisplayPort interface and the miniDP interface developed by Apple. Compared to DVI, DP has made significant progress in bandwidth and customizability.

In May 2006, the Video Electronics Standards Association (VESA) determined the 1.0 version standard and upgraded it to 1.1 version six months later, adding support for HDCP. The 2.0 version is planned to be released this year. As a competitor to HDMI and UDI and a potential successor to DVI, DisplayPort has won support from industry giants such as AMD, Intel, NVIDIA, Dell, HP, Lenovo, Philips, Samsung, etc., and it is free to use.

1. The maximum external connection distance of the DP interface can reach 15 meters, with a rate of up to 10.8 Gb/S, supporting resolutions up to 2560x1600 and color depths of 30/36 bits. 2. It also allows audio and video signals to be transmitted over a single cable, supporting multiple high-quality digital audio formats. 3. In addition to four main transmission channels, it also provides a powerful auxiliary channel with a bandwidth of 1 Mbps, a maximum delay of only 500us, enabling various functions. 4. The Apple miniDP interface is even more powerful, not only being compact but also supporting compatibility with various interfaces, requiring only the addition of an adapter.

Currently, the latest DP interface standard 1.3 can reach a speed of 21.6 Gb/s, directly supporting resolutions up to 4K, mainly applied in PCs, which is why current 4K monitors use DP interfaces.

Comparison between DP and HDMI Interfaces:

HDMI advantages: Many products support HDMI, currently mainstream. Disadvantages: Poor PC compatibility, cannot support 3 or 6 screen multi-screen output.

DP advantages: Perfect PC support, supports 3 to 6 screen outputs. Disadvantages: Introduced late, non-mainstream.

Each USB has only one host, which includes the following layers:
Bus interface
The USB bus interface handles the interconnection of the electrical layer and the protocol layer. From an interconnection perspective, similar bus interfaces are provided simultaneously by devices and hosts, such as the Serial Interface Engine (SIE). The USB bus interface is implemented by the main controller.
The USB system manages data transmission between the host and USB devices using the main controller. Its interface with the main controller depends on the hardware definition of the main controller. At the same time, the USB system also manages USB resources, such as bandwidth and bus power, enabling customers to access USB. The USB system has three basic components:
Main Controller Driver (HCD) This maps different main controller devices into the USB system. The interface between HCD and USB is called HCDI. A specific HCDI is defined by the operating system supporting different main controllers. The Universal Host Controller Driver (UHCD) is at the lowest level of the software structure, managing and controlling the main controller. UHCD implements communication with and control of the USB host controller, and it is hidden from other parts of the system software. The highest layer in the system software communicates with the main controller through the UHCD's software interface.
USB Driver (USBD) It is above the UHCD driver, providing an interface at the driver level to meet the requirements of existing device drivers. USBD provides a data transfer architecture in the form of I/O Request Packets (IRPs), consisting of data transmission needs through specific pipes (Pipes). Additionally, USBD abstracts the client-facing device for easier abstraction and management. As part of the abstraction, USBD has a default pipe. Through this, all USB devices can be accessed for standard USB control. The default pipe describes a logical channel of communication between USBD and the USB device.
Host Software
In some operating systems, there is no provision of USB system software. These software components are originally used to provide configuration information and loading structures to device drivers. In these operating systems, device drivers will use application-provided interfaces instead of directly accessing the USB Driver Interface (USBDI) structure.
USB Client Software
This is at the highest layer of the software structure, responsible for handling specific USB device drivers. The client program layer describes all software entry points that directly act on the device. After the device is detected by the system, these client programs will directly act on the peripheral hardware. This shared characteristic places the USB system software between the client and its device, requiring the client program to handle it based on the device image formed by USBD on the client side.
The host has the following functions for each layer:
Detecting connected and removed USB devices.
Managing data flow between the host and USB devices.
Connecting USB status and activity statistics.
Controlling the electrical interface between the main controller and USB devices, including limited power supply.
HCD provides an abstraction of the main controller and an abstraction of the data transferred via USB from the main controller's perspective. USBD provides an abstraction of USB devices and an abstraction of data transfer between USBD clients and USB functions. The USB system facilitates data transfer between clients and functions and serves as a control point for the normative interface of USB devices. The USB system provides buffer management capabilities and allows data transfer to be synchronized with the needs of both clients and functions.
Hardware Structure Editing
USB uses a four-wire cable, two of which are serial channels for transmitting data, while the other two provide power to downstream (Downstream) devices. For any successfully connected and mutually recognized peripheral, data will be transmitted at the highest rate supported by both parties. The USB bus automatically dynamically converts and matches the appropriate rate in the compatible transmission modes from high speed to low speed according to the peripheral situation. USB is a token-based bus, similar to token ring networks or FDDI token-based buses. The USB host broadcasts tokens, and devices on the bus detect whether the address in the token matches themselves, responding by receiving or sending data to the host. USB manages the power of the USB bus through suspension/resume operations. The USB system adopts a cascaded star topology, which consists of three basic components: host (Host), hub (Hub), and functional devices.
The host, also known as the root, root node, or root hub, is located on the motherboard or installed as an adapter card on the computer. The host contains the main controller and root hub (Root Hub), controlling the flow of data and control information on the USB bus. Each USB system can have only one root hub, which connects to the main controller. A computer may have multiple root hubs.
The hub is a specific component in the USB structure, providing points called ports to connect devices to the USB bus, detecting devices connected to the bus, providing power management for these devices, and being responsible for fault detection and recovery on the bus. Hubs can provide power to the bus and also provide power to themselves (from external sources).
Functional devices connect to the bus through ports. USB can also function as a hub.

When the USB device is connected, the USB system can automatically detect this connection and identify the data transfer rate used. USB identifies low-speed and full-speed devices by adding pull-up resistors on the D+ or D- lines. USB supports three types of transmission rates: 1.5 Mb/s low-speed transmission, 12 Mb/s full-speed transmission, and 480 Mb/s high-speed transmission. When there is no USB device connected to the downstream port of the main controller or hub, the pull-down resistors on the D+ and D- lines make the voltage on these two data lines near ground (0V). After the full-speed/low-speed device is connected, current flows through the voltage divider formed by the pull-down resistor of the hub and the pull-up resistor of the device on D+/D-. Since the value of the pull-down resistor is 15KΩ and the value of the pull-up resistor is 1.5KΩ, a DC high-level voltage of size (Vcc*15/(15+1.5)) will appear on the D+/D- line. When the USB host detects that the voltage on the D+/D- line has approached the high level and other lines remain grounded, it knows that the full-speed/low-speed device has been connected. [9]
High-speed identification
High-speed devices and full-speed devices have the same D+ pull-up resistor. High-speed devices operate at full speed before performing a high-speed handshake. During the reset process, if the device supports high-speed operation, it needs to perform a high-speed handshake with the host. Subsequently, disconnect the pull-up resistor on the D+, enable the high-speed termination resistors on the D+/D-, and operate in high-speed mode.
Unable to identify
First, insert the USB device into the computer interface, then click the "Start" menu in the lower left corner of the desktop, click the "Run" command, open the box and enter the "cmd" command, and click the "OK" button.
Start the command prompt window and execute the following two commands respectively
reg add "HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Environment" /v "DEVMGR_SHOW_DETAILS" /d 1 /t REG_SZ /f
reg add "HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Environment" /v "DEVMGR_SHOW_NONPRESENT_DEVICES" /d 1 /t REG_SZ /f
Restart the computer, enter the "devmgmt.msc" command in the open box, click the "OK" button or right-click the "My Computer" icon on the desktop, select the "Properties" command from the pop-up shortcut menu, switch to the "Hardware" tab in the System Properties window, and click the "Device Manager" button below.
Open Device Manager, click "View" - "Show Hidden Devices" in the menu bar.
Double-click the "Universal Serial Bus Controllers" item, uninstall all gray items and USB mass storage devices below it.
Then right-click the "Universal Serial Bus Controllers" item, select "Scan for Hardware Changes" from the pop-up drop-down menu.
Remove and reinsert the USB device. Is it better now?
If not, right-click the "USB Root Hub" item under "Universal Serial Bus Controllers", and click the "Properties" command in the pop-up right-click menu.
In the opened properties window, switch to the "Power Management" tab, uncheck "Allow the computer to turn off this device to save power", and click the "OK" button (modify the properties of each USB Root Hub in sequence).
Power shortage editing
1. External power supply method
With the continuous improvement of various technical indicators of USB devices, its working current is also "steadily increasing". For example, some mobile hard drives with particularly fast rotation speeds sometimes reach a working current of 1A standard, which exceeds twice the normal power. Therefore, it is not realistic to rely solely on the USB interface to provide sufficient power for USB devices. To address this, when using high-power USB devices, we must provide them with an independent external power supply to ensure the stability of both the USB device and the computer system.
2. Interface replacement method [10]
Many USB device manufacturers in the 1920s of the 21st century often provided several different connection interfaces for their USB devices so that they could have enough "playground". If the USB device cannot obtain sufficient power from the USB interface, it can use other ports with less power consumption to connect, ensuring that the USB device can be used normally. For example, when the USB interface of certain mobile hard drives is connected to older motherboards, it often fails to work properly. However, if another PS/2 interface is used to connect to the computer, the mobile hard drive can work normally.
3. Power reduction method
Under normal circumstances, the power supply for each USB port on the motherboard is 0.5A. If the rated current of the USB device exceeds this standard when it is working normally, the motherboard will fail to accurately recognize the USB device; at this point, the only feasible solution is to choose USB devices with low power consumption or USB devices with independent power supply to ensure normal operation of the USB device.
4. Exclusion method
The so-called "exclusion method" is to remove other temporarily unused USB devices from the motherboard's USB ports, leaving only the urgently needed USB device, so that the motherboard can independently provide power for the USB device, thus ensuring that the device can work normally. Considering that each pair of USB ports in new motherboards is powered separately, if other USB devices are inserted into the same group as the current USB device, the power energy obtained by the current USB device from the motherboard will be affected. Therefore, when you find that the current USB device lacks power, you must remove other temporarily unused USB devices or insert them into another group of USB ports.

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