Questions tagged [vga]

stands for Video Graphics Array and provides a 640x820 screen resolution.

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29 votes
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Why does VGA have so many ground pins (compared to DVI-I for example)?

If you look at the pinout for VGA, there are several ground pins: I was curious as to why, and I found this answer. To sum it up, the extra ground pins are so that each pin has its own ground in ...
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18 votes
2 answers
5k views

What are 'return' pins?

On a VGA connector, there are numerous 'ground' pins. Three of these are Red return, Green return and Blue return; But why does each color component have its own ground pin?
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14 votes
4 answers
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How is it possible to drive VGA displays at such high pixel clock frequencies?

I'm working on a digital circuit using discrete components to drive a 640x480 VGA display in a 80x30 text mode. For a 640x480 display, the pixel clock is 25.175MHz, which has a period around 40ns. I ...
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13 votes
3 answers
12k views

VGA Output from Arduino

Is there any method to output VGA with Arduino?
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10 votes
1 answer
12k views

How exactly does a VGA cable work?

I've been looking around on the internet and I can't find anything in depth on how the cable/connection functions. I've only been able to find simple pin out descriptions. If someone can link me or ...
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10 votes
2 answers
756 views

Ghosting in VGA signal generation

So, I'm generating a 1280x1024 (native screen resolution) VGA signal using a Lattice HX8K > Yosys, according to these timings, and a PLL of 107.812Mhz of Pixel Frequency. I then pass it through a ...
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8 votes
4 answers
18k views

How to utilize HDMI port on FPGA (basic)

Two questions. I have a Xilinx Spartan 6 FPGA which only has HDMI ins and outs. Is there some sort of guide or pre-written code that I can use to start sending images to the screen? I have no idea ...
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8 votes
2 answers
1k views

Does VGA have to be drawn at 60hz?

I'm wanting to generate a VGA signal hopefully as painlessly as possible. I have an odd question though. Everywhere I see that VGA requires a 25MHz clock for the sync signals. Is it possible to ...
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  • 3,306
8 votes
2 answers
9k views

FPGA VGA Buffer. How to read and write?

I have an Altera DE2 board and trying to draw sprites. I am having some trouble implementing a screen buffer. I have a display entity that at a 25 MHZ rate outputs pixels for vga display. I was ...
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8 votes
1 answer
2k views

How Significant is VGA Impedance Matching?

I've seen a multitude of different resistor DAC solutions for a VGA signal, however they almost always have an impedance of >200 ohms per color, e.g. when I've been lead to believe that we want to ...
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8 votes
2 answers
4k views

How to implement memory mapped IO

I am describing a system in VHDL. This system already contains a processor, a DDR SDRAM controller and a VGA controller. VGA reads pixels from SDRAM (already validated and proven in FPGA). Although ...
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7 votes
5 answers
714 views

Spacewar on microcontroller

First of all I need to say that I have almost no experience with programming microcontrollers (aside for some Arduino stuff). I have worked with C (and x86 ASM) on some low level projects (think of ...
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  • 205
7 votes
4 answers
3k views

Can we attach LED to VGA port and make it light up, the same way we do in Parallel Port?

I just connected an LED to a parallel port in my PC and controlled it successfully through inpout32.dll I was wondering, if it was possible to do the same with the VGA port. Where can I find ...
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7 votes
1 answer
8k views

Do-It-Myself KVM?

I have several computers (desktops) in different geographical locations that I want to access remotely. Commercial KVM-over-IP solutions that I found are expensive (more than 200 euros each) and the ...
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  • 173
7 votes
2 answers
1k views

Why doesn't my VGA implementation using an AVR microcontroller work?

Problem I'm trying to generate the appropriate signal output for interfacing an AVR ATmega328P microcontroller with an LCD monitor, via the VGA specification. The VGA specification I am trying to ...
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7 votes
2 answers
5k views

VGA interfacing with PIC

I'm looking for a way to control a VGA screen with a PIC. External components are OK, so a VGA chip with I2C or SPI or something is okay too. Requirements: Resolution: max 1024x768, no minimum ...
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6 votes
5 answers
7k views

VGA to HDMI converter

I'm making a little project purely as a hobby using a small FPGA breakout board. I'm outputting VGA video which works fine, but would like HDMI output instead so I can connect to a television that has ...
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  • 2,067
6 votes
2 answers
984 views

Trouble with VGA Controller on CPLD

What I am attempting to do is create a VGA controller from a Lattice MachXO CPLD in Verilog. The Problem I am attempting to display the color red with a resolution of 640x480 @ 60Hz using a 25.175 ...
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  • 223
6 votes
1 answer
3k views

VGA Decoding - Dealing with tolerances

Update: The VGA Simulator is up and running. You can go simulate your own designs or just use the example file to see it working. I also wrote a blog post to help anyone get started using it for ...
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  • 838
5 votes
1 answer
3k views

Other name for VGA socket?

I need a VGA socket for my project (preferably PCB mounted but that's not reevent probably). But I can't find such a thing at any of my usual suppliers. I presume they have some other name I need to ...
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  • 2,067
5 votes
2 answers
10k views

What is the acceptable current draw on pin #9 on a VGA connector?

I'm trying to appropriate the 5v that comes into an LCD monitor on pin #9 of a VGA connector to power a microcontroller with some sensors, and LEDs. I've found a discussion on this topic on a ...
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  • 251
5 votes
2 answers
2k views

How to make a VGA monitor display a white screen at all time?

I am hacking around with an old (CRT) VGA monitor. Trying to make an oscilloscope. What I want is to make the monitor display a blank white screen at all time, when the power is connected of course. ...
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  • 153
5 votes
1 answer
975 views

How to attenuate a (seemingly) overdriven VGA signal

I own an 8 port Belkin OmiPro2 KVM switch, which is a device used to connect multiple computers to a single display/mouse/keyboard. I've owned this KVM for years and it has exhibited the same symptom ...
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  • 153
5 votes
3 answers
6k views

VGA signal timing calculation using MCU

I want to generate VGA signal with microcontroller. But I have hard time finding solution online how to generate them in software. For e.g. Usually all online VGA signal generation just explains ...
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  • 183
5 votes
1 answer
678 views

Can the DS1052E be used for reliable NTSC measurement?

I'm in the market for an oscilloscope. I've read that the infamous DS1052E from Rigol is a great beginner scope due to the price/performance. However, I know I have a lot to learn and simply don't ...
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5 votes
1 answer
2k views

How does a computer signal via VGA for the monitor to sleep [closed]

Could somebody please explain how a "modern" monitor is told to sleep. I need to know this for a VGA with blue connector, i.e. it has DDC. I've heard that the sync stops. If true, which sync? ...
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  • 161
4 votes
2 answers
2k views

Is this how a R-2R DAC for VGA should work?

I'm trying to wrap my head around if this is how a R-2R DAC should work. I say should for two reasons: (1) because I think I understand the theory behind the resistor ladder of subsequent voltage-...
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4 votes
1 answer
676 views

Convert from VGA 9 pin to RCA (manually - old machine) [closed]

I'm in a trouble. Can someone help me? I have a very big machine where I had mounted an IBM 5151 monitor by VGA. The VGA cable was connected to the card below (see attachment), by 4 wires. Now the ...
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4 votes
2 answers
4k views

How VGA monitor detects video resolution?

How VGA monitor detects video resolution. I'm asking this because with different VSYNC, HSYNC intervals it's possible to have different dot clock.
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  • 293
4 votes
1 answer
744 views

having distorted image in VGA with FPGA board

I'm using spartan 3E-100 CP132 fpga board to display a basic plus image on a monitor. I have tried using 800x600 72 hz and 640x480 60 Hz but I always get a distorted vertical lines. Is it because the ...
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4 votes
2 answers
9k views

How does a PC detect a VGA monitor?

Currently I am trying to connect my LCD to my laptop through a VGA connector. The LCD has 6 wires out of it which I am trying to solder to a VGA male connector, But the laptop doesn't detect the LCD. ...
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  • 161
4 votes
1 answer
2k views

Is there an FPGA based vector graphics card project?

I have been messing around with VGA projects as my latest interest. I have a Xilinx Spartan 3E 250K FPGA, which has just barely too little RAM for a full 640x480 frame buffer. So, I'm looking at ...
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  • 3,306
4 votes
3 answers
5k views

What's the simplest way to generate a VGA signal for a totally white screen? Preferably with an AVR MCU

I'd like to make a simple board to plugin a LCD monitor and get a blank white screen. The idea is to use any monitor as a makeshift light table. I have a preference for 8-bit AVR micros since I have a ...
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  • 143
3 votes
2 answers
8k views

VGA to composite circuit. Does it work?

I found a VGA to composite passive converter circuit online, and was wondering if it would work, if the VGA timings were modified to match the timing of composite. Here is a relevant schematic:
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3 votes
5 answers
2k views

Is it safe to assume that all pins in a standard VGA cable are wired?

I am currently in the process of designing a custom arcade-style joystick console for use with emulators on my PC. My design separates each joystick console from a single keyboard-encoder "hub" such ...
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3 votes
2 answers
146 views

Why do VGA VSYNC and HSYNC need 47 ohm resistors in this schematic?

In Chapter 3 in this document there is a schematic showing a connection to VGA. Why is there a 47 ohm resistor connected to VSYNC (GPIO17) and HSYNC (GPIO16)? I managed to understand the other ...
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3 votes
3 answers
2k views

VGA monitor as the display for VHS player

How do I connect an LCD monitor to be the display for a VHS VCR?
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3 votes
4 answers
1k views

Video Controller Design

I'm designing my own computer based on the Zilog Z80. It has 256KiB of static RAM with paging as well as a few megabytes of flash memory. Everything is going along pretty well until * BAM * I hit a ...
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  • 1,872
3 votes
3 answers
558 views

How to determine if a video signal is interlaced

I know what the difference between interlaced and progressive scan is: in progressive video modes, the monitor displays all the lines of a video field sequentially. In interlaced, it displays them on ...
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3 votes
2 answers
2k views

How to calculate resistor values for a VGA DAC

I have an FPGA and want it to drive a VGA monitor. I want more than 3 bits of color so I need a DAC of some sort. So I want to make a resistor dac. My plan is to have 3 bits per subcolor. So total of ...
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3 votes
6 answers
15k views

What determines the number of pixels in front porch and back porch of VGA display?

Besides this, is pixel clock dependant on the VGA resolution and referesh rate or independant of them? What does one know what duration each pixel should have?
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  • 9,699
3 votes
2 answers
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SCART to VGA adapter - green picture

I want to connect my DVD player which has a SCART output to a computer LCD monitor with VGA input. The DVD player supports the Progressive scan mode. It supports both PAL and NTSC. I've built this ...
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  • 5,008
3 votes
2 answers
3k views

male-male VGA cable wiring

I need to build a VGA cable (assemble connectors to wire). I need a male-male cable. Is its wiring straight or cross? (should i connect 1-1,2-2,... or something else) Thanks
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  • 301
3 votes
2 answers
3k views

Resistor DAC and buffer for VGA output

I'm in the process of designing a very simple binary weighted resistor DAC for an output stage of a RGB VGA driver. There will be 3 bits for R and G components and 2 for B. The output signal is analog ...
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  • 143
3 votes
2 answers
2k views

VGA driver not working

I am at the moment trying to make an vga driver for my FPGA, but something isn't going right, and I can't seem to find out what is going wrong... The code is based on this code example: Example VGA ...
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3 votes
4 answers
2k views

Is quality of VGA Horizontal and Vertical sync Pulse relevant to be able to display on sensitive projectors

I am currently trying to diagnose a VGA problem on hardware A. Hardware A has some trouble sending display to certain projectors (while it is able to send display on most LCD monitors). Hardware B ...
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  • 71
3 votes
2 answers
2k views

Custom VGA output : what resolutions are expected to work?

I am thinking of creating a device which displays graphics and animation to generic computer display with 16:9 aspect ratio via analog interface (D-sub). The question is which resolutions are ...
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  • 3,231
3 votes
1 answer
139 views

Character mask VGA display

Im building a VGA (640x480@60Hz) adapter for my homebrew project but i dont have enought memory to store a framebuffer. Since im using 8 bit memory i plan to do 8 bit color, but 8 colors would be ...
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  • 85
3 votes
1 answer
941 views

Reverse-engineering VGA

I got a x86-based firewall, produced by Stonesoft. It has serial interface, but it would be easier to install new operating system if I would get VGA output from the device. I discovered promising ...
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  • 146
3 votes
2 answers
1k views

What impedances do graphics cards expect on H-Sync and V-Sync for VGA monitors?

I have a graphics card for a laptop whose driver kills itself if it runs for longer than two minutes with no external monitor attached. To solve that, I decided to make a sort of dummy plug that would ...
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