VGA or Video Graphics Array refers to display hardware that was introduced with the IBM PS/2 line of computers in 1987. Due to the widespread adoption of the technology, VGA has become the colloquial term used to describe the analog computer video signal that is produced or received by a computer or monitor as well as the HD15 connector. This signal and connector have long been the standard for computer video.
The HD15 connector is a DB-style connector that contains three rows of five pins for a total of fifteen pins. Many of the cables sold today that use the HD15 connector omit the 9th pin leaving a total of 14 pins. The original purprose of this pin was to carry +5VDC power from the video card in order to power accessories. Since these accesories were never widely adopted, this pin is no longer used and is omitted from cables designed for computer video.
The analog computer video signal is composed of five different components, red video, green video, blue video, horizontal sync, and vertical sync (RGBHV.) The red, green and blue signals represent the image's color information, while the sync lines provide the "blue print" to construct the image. In addition to the video signal, a VGA cable will also carry identification information from the monitor to the computer. Digital Display Channel (DDC) and the companion signal Extended Display Identification Data (EDID) make compunter monitors "plug and play" devices. The DDC and EDID information provide the computer's video card with the monitor's capabilities and supported graphic modes.
|1||Red Video||Carries the Red color information of the video signal|
|2||Green Video||Carries the Green color information of the video signal|
|3||Blue Video||Carries the Blue color information of the video signal|
|4||Reserved||Before E-DDC this carried identification information from the monitor, this pin is now reserved/unused|
|5||H. Sync Ground||Electrical ground for the Horizontal Sync signal|
|6||Red Ground||Electrical ground for the red color information of the video signal|
|7||Green Ground||Electrical ground for the green color information of the video signal|
|8||Blue Ground||Electrical ground for the blue color information of the video signal|
|9||Reserved/+5VDC||Reserved/unused. In the original specification this carried power from the video card to a monitor for the purpose of supporting future features|
|10||V. Sync/DDC Ground||Electrical ground for the Vertical Sync and DDC signals|
|11||Reserved||Before E-DDC this carried identification information from the monitor, this pin is now reserved/unused|
|12||DDC Data (SCA)||Carries identification information, EDID, from the monitor|
|13||H. Sync||Carries Horizontal Sync signal used to build the video image|
|14||V. Sync||Carries Vertical Sync signal used to build the video image|
|15||DDC Clock (SCL)||Carries identification information, EDID, from the monitor|
High Definition Multimedia Interface (HDMI®) is a term that is used to describe a set of connectors, as well as an uncompressed digital audio/video signal. HDMI was created by major electronics manufacturers, including, Hitachi, Phillips, Sony, Toshiba, and others. HDMI was the first uncompressed all digital interface that was able to carry both audio and video signals. Though commonly found on consumer electronic devices, such as Blu-ray players, the HDMI interface is now used as an audio/video output for laptops and desktop computers.
Per the latest HDMI specification, version 1.4, there are four different connector types defined. The type A HDMI connector is the most common. The type A connector is a 19-pin connector and is used on devices such as laptop and desktop computers, Blu-ray players, and more. The type B HDMI connector is designed for future high-resolution (WGUXGA - 3840 x 2400) displays and has not yet been used on current devices. The type C, or Mini-HDMI connector is smaller than the type A connector, but uses the same 19-pin configuration. This connector is commonly found on portable devices, such as handheld video camers. The type D, or Micro HDMI connector is smaller than the type C connector, but also uses the same 19-pin configuration. This connector is commonly found on small portable devices such as smartphones. The final connector is the type E, or Automotive HDMI connector which uses the same 19-pin configuration. This connector is designed to be used for in-vehicle HD content distribution and to meet the rigors and environmental issues commonly found in automobiles, such as heat, vibration and signal interference.
HDMI specifications outline the features that are included with the audio/video signal, i.e. HDMI Ethernet channel, audio return channel, 3D, etc. The HDMI specification has also outlined five different cable types: Standard Speed, Standard Speed with Ethernet, Standard Automotive, High Speed, and High Speed with Ethernet. Standard Speed cables are capable of reliably supporting 1080i or 720p video resolutions. Standard Speed with Ethernet cables support the same resolutions as Standard Speed cables as well as supporting the HDMI Ethernet channel functionality. Standard Automotive Cables support the same resolutions as Standard Speed, and are designed to be used for in-vehicle HD content distribution as well as to meet the rigors & environmental issues commonly found in automobiles. High Speed with Ethernet cables support the same resolutions and features as the High Speed cables as well as the HDMI Ethernet channel functionality.
In addition to the audio/video signal and features, the HDMI signal includes content protection. High-Bandwidth Digital Content Protection (HDCP) was created by Intel to protect digital content such as movies and programming from unauthorized duplication. HDCP require that devices echange information in the form of a digital handshake before content will be displayed. All of these signals, audio and video, features, and content protection, are carried by Transition Minimized Differential Signaling (TMDS.) The number of TMDS links is ued to categorize the HDMI connector types. Type A, C, D, and E HDMI connectors have one TMDS link are considered single-link connectors. Type B HDMI connectors have two TMDS links and are considered dual-link connectors. The second TMDS link in the type B HDMI connector allows more information to be carried over the cable which allows for higher resolutions.
|1||TMDS Data 2+||Carries audio and video data|
|2||TMDS Data 2 Shield||Electrical ground for the audio and video TMDS lines|
|3||TMDS Data 2-||Carries audio and video data|
|4||TMDS Data 1+||Carries audio and video data|
|5||TMDS Data 2 Shield||Electrical ground for the audio and video TMDS lines|
|6||TMDS Data 1-||Carries audio and video data|
|7||TMDS Data 0+||Carries audio and video data|
|8||TMDS Data Shield||Electrical ground for the audio and video TMDS lines|
|9||TMDS Data 0-||Carries audio and video data|
|10||TMDS Clock+||Carries information that aids in signal synchronization|
|11||TMDS Clock Shield||Electrical ground for the TMDS Clock lines|
|12||TMDS Clock-||Carries information that aids in signal synchronization|
|13||CEC||Carries control and command data between devices (Consumer Electronics Control)|
|14||Reserved||Unused, reserved for future use|
|15||DDC Clock (SCL)||Carries identification information, EDID, between the source and display device|
|16||DDC Clock (SDA)||Carries identification information, EDID, between the source and display device|
|17||DDC/CEC Ground||Electrical ground for the DDC and CEC signals|
|18||+5V Power||Carries +5VDC power supple from the source device|
|19||Hot Plug Detect||Monitors power up/down and connect/disconnect events|
DisplayPort is a digital display standard proposed by the Video Electronics Standards Association (VESA). The standard defines a royalty-free digital audio/video interconnect that is intended to connect a computer to a computer monitor or HDTV. This connector was designed to replace the VGA and DVI connectors that are commonly used for the video output of a computer. Though DisplayPort offers the same functionality was the HDMI connector, it is not expected to replace the HDMI connector in consumer electronics.
There are two different types of the DisplayPort connector, internal and external. The internal connector has 30/20 pins and is designed to provide a connection between a graphics card and a built-in flat panel. This type of connector would be found inside of laptop computers. The external connector has 20 pins and is secured by latch clips. This type of connector is found on computers, computer monitors, HDTVs, etc.
DisplayPort signals are composed of a unidirectional main link which carries the audio/video data and a half-duple bi-directional auxiliary channel which carries monitor information. The DisplayPort signal is carried by micro-data packets. This means that the signal is not directly compatible with HDMI or DVI. However, dual-mode DisplayPort video cards are able to transmit single-link HDMI and DVI signals through a passive video adapter. Active powered video adapters allow for signal conversion to Dual-Link DVI and analog VGA.
|1||Main Link Lane 0+||Carries audio and video data|
|2||Main Link Lane 0 Ground||Electrical ground for the audio and video link lines|
|3||Main Link Lane 0-||Carries audio and video data|
|4||Main Link Lane 1+||Carries audio and video data|
|5||Main Link Lane 1 Ground||Electrical ground for the audio and video link lines|
|6||Main Link Lane 1-||Carries audio and video data|
|7||Main Link Lane 2+||Carries audio and video data|
|8||Main Link Lane 2 Ground||Electrical ground for the audio and video link lines|
|9||Main Link Lane 2-||Carries audio and video data|
|10||Main Link Lane 3+||Carries audio and video data|
|11||Main Link Lane 3 Ground||Electrical ground for the link lines|
|12||Main Link Lane 3-||Carries audio and video data|
|14||Ground||Carries audio and video data|
|15||AUX Ch+||Bi-directional data carried between the monitor and the source|
|16||AUX Ch Ground||Electrical ground for the AUX channel|
|17||AUX Ch-||Bi-directional data carried between the monitor and the source|
|18||Hot Plug Detect||Monitors power up/down and connect/disconnect events|
|19||Power Return||Power return from the monitor|
|20||Power (3.3V 500mA)||Power provided to the monitor|
Digital Visual Interface (DVI) is a video interface that was designed by an industry consortium, the Digital Display Working Group (DDWG), to replace VGA. There are two different tpes of DVI connectors, the DVI-I and DVI-D. DVI-I carries an uncompressed digital video signal and is also capable of carrying an analog video signal. DVI uses TMDS to transmit the video data and both Single-Link and Dual-Link connections are possible.
The two different types of DVI connectors are distinguished by the pin configuration. Both connector types will have a grounding bar, pin #C5, which is separate from the pins. The DVI-I connector has four additional pins that surround the grounding bar. The DVI-D connector does not have any pins surrounding the grounding bar. The number of pins in a DVI connector will also indicate whether the cable will support a Single-Link or a Dual-Link TMDS connection. A Single-Link DVI connector, DVI-I or DVI-D, will have three rows of six pins for a total of eighteen pins. Six pins in the middle of the connector will not be present. A Dual-Link DVI connector, DVI-I or DVI-D will have three rows of eight pins for a total of twenty-four pins. The full complement of twenty-four pins allows the Dual-Link DVI connectors to carry an additional TMDS link which allows for the support of higher resolution video.
The digital DVI signal is identical to the HDMI signal minus the audio portion. The digital signal is supported by both the DVI-I and DVI-D connector. Adapter cables that have both a DVI-D connecotr and HDMI connector can be used to connect an HDMI monitor to a DVI-I or DVI-D video output on a computer. DVI-I connectors that also have the ability to carry analog video signals. The analog DVI signal is identical to the VGA signal. Adapter cables that both a DVI-I and VGA connector can be used to connect a VGA monitor to a DVI-I video output on a computer.
|1||TMDS Data 2-||Carries video data|
|2||TMDS Data 2+||Carries video data|
|3||TMDS Data 2/4 Shield||Electrical ground for the video TMDS lines|
|4||TMDS Data 4-||Carries video data (Dual-Link only)|
|5||TMDS Data 4+||Carries video data (Dual-Link only)|
|6||DDC Clock (SCL)||Carries identification information, EDID, from the monitor|
|7||DDC Clock (SDA)||Carries identification information, EDID, from the monitor|
|8||V.Sync (DVI-I only)||Carries vertical sync information used to build an analog video image|
|9||TMDS Data 1-||Carries video data|
|10||TMDS Data 1+||Carries video data|
|11||TMDS Data 1/3 Shield||Electrical ground for the video TMDS lines|
|12||TMDS Data 3-||Carries video data (Dual-Link only)|
|13||TMDS Data 3+||Carries video data (Dual-Link only)|
|14||+5V Power||Carries +5VDC power supply from the source device|
|16||Hot Plug Detect||Monitors power up/down and connect/disconnect events|
|17||TMDS Data 0-||Carries video data|
|18||TMDS Data 0+||Carries video data|
|19||TMDS Data 0/5 Shield||Electrical ground for the video TMDS lines|
|20||TMDS Data 5-||Carries video data (Dual-Link only)|
|21||TMDS Data 5+||Carries video data (Dual-Link only)|
|22||TMDS Clock Shield||Electrical ground for the TMDS clock lines|
|23||TMDS Clock+||Carries information that aids in signal synchronization|
|24||TMDS Clock-||Carries information that aids in signal synchronization|
|C1||Red Video (DVI-I only)||Carries the red video information of an analog video signal|
|C2||Green Video (DVI-I only)||Carries the green video information of an analog video signal|
|C3||Blue Video (DVI-I only)||Carries the blue video information of an analog video signal|
|C4||H.Sync (DVI-I only)||Carries the horizontal sync signal used to build an analog video image|
|C5||Common Ground (DVI-I only)||Electrical ground for red, green, and blue video data. Unused in a DVI-D cable.|
|VGA||HDMI Type A||HDMI Type B||HDMI Type C/D/E||DisplayPort Internal||DisplayPort External||DVI-I||DVI-D|
|Signal Type||Analog||Digital||Digital||Digital||Digital||Digital||Digital or Analog||Digital|
|Pin Count||14 (15)||19||29||19||20/30||20||24+4+1 |
|Distance||75ft||5m (16.4ft)||5m (16.4ft)||5m (16.4ft)||15m (49.2ft)||15m (49.2ft)||5m (16.4ft)||5m (16.4ft)|
This white paper is for informational purposes only and is subject to change without notice. C2G makes no guarantees, either expressed or implied, concerning the accuracy, completeness or reliability of the information found in this document.