The VGA port was used for the first time in the IBM PS / 2, released in 1987, and for years it became the video output par excellence in PCs until it was completely replaced by ports designed for LCD monitors such as DVI, HDMI and DisplayPort. However, if you have a VGA monitor stored there that is fully functional but your graphics does not support a VGA output then we are going to give you a solution,
If you have a fully functional CRT monitor and collecting dust, we give you a reason to connect it to your PC and how you can do it.
Why do we want a CRT monitor?
Using out-of-market and outdated technology may seem counterproductive and illogical to us, but there is a reason for it. Many LCD screens, including newer ones, have a moving resolution much lower than their static resolution.
This means that they take much worse the transition of frames than the CRT and this is due to the time in which the LCD screens need to vary the value of the pixels.
At the moment, LCD screen manufacturers have been launching monitors with a high frequency on the market, but if you have a CRT screen lying around, it may be useful, especially for competitive games such as eSports, plus you will not need one Very powerful GPU to run at the resolution at which a CRT works and with a high refresh rate.
The monitors used to be different
CRT monitors did not make use of modern video interfaces such as HDMI and DisplayPort but a video interface called VGA. To understand how the VGA port works we have to take into account how it communicated with the graphics card and for this we have to know what each of its pins does.
The VGA is an RGB video connector, this means that it has channels for the three main components (red, green and blue) separately, We can also see the HSYNC and VSYNC pins and it is that in graphics cards with VGA output it has to the graphics chip itself being in charge of counting the times of the active screen.
VGA technology was devised when everyone used tube monitors, where the electron beam travels the screen to generate the image and it does so so quickly that our eyes think that the pixels we see on the screen are still pixels assets. The reality is that the VGA output works the same as the video interfaces found in tube televisions, but with a higher bandwidth to achieve a higher resolution and refresh rate.
On the other hand, LCD monitors are different, there is not an electron beam that travels the screen but a large number of pixels that are activated by a huge number of LEDs to compose the pixels, so it is no longer necessary to count the times active screen.
Why can’t we use a VGA monitor with an HDMI port?
If we look at the pinout of the HDMI port we will see that a series of pins are missing that are found in a VGA such as HSync and VSync, this is because in HDMI systems it is not the graphics chip that controls the timing of resolution, but these are controlled by the controller inside the HDMI cable.
This means that any HDMI signal cannot be connected with a simple redirection of the pins to a VGA output directly. That is, we can manipulate an RGB output as the component output to convert it to a VGA output, for example, simply by routing the pins, but with HDMI this is not possible, so a help in the form of an intermediate converter is necessary. .
HDMI to VGA converter
The idea is to use a modified HDMI receiver, but instead of sending the signal to the internal controller of an LCD screen, the idea is to send this information to a DAC or a digital to analog converter that allows sending the analog signal to a VGA output. There are two ways to do this.
- Use an FPGA or CPLD that has been configured to perform the function of converting the signal for HDMI into something that the VGA output can understand.
- Make use of components already on the market designed for this function,
One solution is the CN0282 board from Analog Devices:
It is a device used in the automotive world where a large number of LCD screens have a VGA interface due to the fact that they do not have the resolution and do not require the bandwidth of HDMI. In addition, this board has audio extraction and we must remember that the VGA does not support the audio signal, which would be lost in the process, so it allows us to recover the audio from the source source.
The problem with this solution is that it does not support HDCP, so if the content you want to transmit is encoded via HDCP you will not be able to see it on your VGA monitor.
The simplest solution, an HDMI to VGA cable
There is a much better and simpler solution than using an HDMI to VGA converter, with the added problem that the audio signal will be completely lost in the process, so if you don’t mind this at all you can go for an HDMI cable. to VGA. On the other hand, keep in mind that this cable does support HDCP.
