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Let's Build a Video Card

eater.net

11–20 of 27 posts

Re: Let's Build a Video Card

#11
post #3

I was surprised to read how much his materials cost for this. $88, all told - you would think building a (pretty much the simplest possible) video card would be cheap!

$56 of which is breadboard and hook up wire - I'm sure it's possible to have a custom pcb fabbed for about $20,and if you do small runs to have the pcb cost drop to less than $1.

You could also buy the breadboards for ~$2 each on aliexpress.

Re: Let's Build a Video Card

#12

I'm interested in learning more about VGA and HDMI, because I'd like to build a hardware freeze button. On an old church projector, there was a button on the remote so I could freeze the screen. Then I could switch from PowerPoint to QuickTime Player (or whatever else) without disturbing everybody who was watching. Newer equipment (some projectors, most TVs) lack this feature. I'd like to build a box that stores the…

I wonder if you could do this with an HDFury Vertex or Integral. All the hardware is there (including dealing with HDCP), but I don't think they have devkits available that would let you add features to the firmware.

Re: Let's Build a Video Card

#13
post #11
post #3

Earlier quoted context omitted.

$56 of which is breadboard and hook up wire - I'm sure it's possible to have a custom pcb fabbed for about $20,and if you do small runs to have the pcb cost drop to less than $1.

You could also buy the breadboards for ~$2 each on aliexpress.

But then you get crappy breadboards that once in a while gives a bad connection. Without any visual clue. That can be very hard to debug, especially for the hardware newbie Ben Eater is teaching. Spending an extra $50 to make the process hassle free and enjoyable is money well spent.

Re: Let's Build a Video Card

#14
post #4

I was surprised to read how much his materials cost for this. $88, all told - you would think building a (pretty much the simplest possible) video card would be cheap!

About half of that cost ($40) is the 5 breadboards needed to connect the circuit together. Building it on something more permanent like veroboard would cut that cost down significantly.

If the purpose of the project is learning and experimentation, then there's not much to recommend veroboard. I have to think so carefully about how to place components, where to cut tracks to make connections, how best to route jumpers, etc. and after all that, it's difficult to change things when debugging or just to tinker.

Breadboards offer a huge amount of flexibility over veroboard, at the expense of size and permanence.

Re: Let's Build a Video Card

#15

I'm interested in learning more about VGA and HDMI, because I'd like to build a hardware freeze button. On an old church projector, there was a button on the remote so I could freeze the screen. Then I could switch from PowerPoint to QuickTime Player (or whatever else) without disturbing everybody who was watching. Newer equipment (some projectors, most TVs) lack this feature. I'd like to build a box that stores the…

If an off the shelf solution is okay, look into live veejay/VJ software and hardware, or maybe game streaming/screencasting or other live broadcast tools. You can add VGA and HDMI capture cards to a computer, then use software to pause or switch inputs.

Re: Let's Build a Video Card

#16
post #11

Earlier quoted context omitted.

You could also buy the breadboards for ~$2 each on aliexpress.

But then you get crappy breadboards that once in a while gives a bad connection. Without any visual clue. That can be very hard to debug, especially for the hardware newbie Ben Eater is teaching. Spending an extra $50 to make the process hassle free and enjoyable is money well spent.

Better yet, use wirewrapping (https://en.wikipedia.org/wiki/Wire_wrap) instead of breadboarding, so quality of the board doesn't matter. Buy a wirewrap stick (20 USD), some crappy perfboards from China (10 USD), some wires (5 USD), some long DIP headers (10 USD), and you're good to go. You may still need two or three breadboards for quick experiments.

I'm currently working on a homebrew Z80 computer. I'm at the stage of moving the preliminary designs to PCBs, but from my experience, wirewrapping is a lot better than breadboarding when you start building circuits with many signal wires. Breadboards are quick and simple at first when you can "plug and play", but it would quickly become a nightmare when the number of connections and wires exceed 200. It may be a less concern for a modern microcontroller as i2c and SPI are serial interfaces, but on a 8-bit computer, you'll hit this number really quickly, because the system bus is 24-bit (16-bit addr, 8-bit data), parallel. A bus driver using two unidirectional buffer has 24 x 2 + 8 = 56 wires, two RAM chips have 48 wires, a ROM has another 24 wires, it's already 148 wires now for a bare-minimum system without even an I/O port. It will get out of control soon. Also, a 16-bit machine will become a nightmare even quicker as they have 32-bit bus.

On wirewrapped boards, you'll never get a bad connection without any visual clue, the connection is as solid as soldering, and there are no jumper wires hanging in the mid-air to stop you from probing it using an oscilloscope. Strongly recommended, to learn more, search keywords "wirewrap electronics" at YouTube.

Re: Let's Build a Video Card

#17

I'm interested in learning more about VGA and HDMI, because I'd like to build a hardware freeze button. On an old church projector, there was a button on the remote so I could freeze the screen. Then I could switch from PowerPoint to QuickTime Player (or whatever else) without disturbing everybody who was watching. Newer equipment (some projectors, most TVs) lack this feature. I'd like to build a box that stores the…

If an off the shelf solution is okay, look into live veejay/VJ software and hardware, or maybe game streaming/screencasting or other live broadcast tools. You can add VGA and HDMI capture cards to a computer, then use software to pause or switch inputs.

Yes, I bought an Elgato Cam Link 4K recently, and I could do it with CamTwist. I'd rather reduce the lag though, and the physical size/complexity of an extra computer.

Re: Let's Build a Video Card

#18

I'm interested in learning more about VGA and HDMI, because I'd like to build a hardware freeze button. On an old church projector, there was a button on the remote so I could freeze the screen. Then I could switch from PowerPoint to QuickTime Player (or whatever else) without disturbing everybody who was watching. Newer equipment (some projectors, most TVs) lack this feature. I'd like to build a box that stores the…

This is actually a rather involved thing that you want to do here. Short answer is that you really need a presentation switcher or something similar that uses FPGA. If you want to roll your own, you can do it, but it's probably not gonna be worth the time investment.

NETV2 (Libre mode) is probably the best bet for hardware that will both do the job and has at least some example stuff that will be similar. It's FPGA based, but it will require a lot of effort to implement.

Other than that you are looking at the HDMI or DVI TxRx cards along with an FPGA dev board. Terasic's Altera boards and expansion cards, for instance will do the job and they offer VGA, DVI and HDMI interfaces for a large number of their dev boards. Anything along this vein will cost a lot more than NeTV2

IMO If you want to rely on something for a large commercial public presentation, I really wouldn't hack something together. Just buy a presentation switcher.

Re: Let's Build a Video Card

#19

Earlier quoted context omitted.

But then you get crappy breadboards that once in a while gives a bad connection. Without any visual clue. That can be very hard to debug, especially for the hardware newbie Ben Eater is teaching. Spending an extra $50 to make the process hassle free and enjoyable is money well spent.

Better yet, use wirewrapping ( https://en.wikipedia.org/wiki/Wire_wrap ) instead of breadboarding, so quality of the board doesn't matter. Buy a wirewrap stick (20 USD), some crappy perfboards from China (10 USD), some wires (5 USD), some long DIP headers (10 USD), and you're good to go. You may still need two or three breadboards for quick experiments. I'm currently working on a homebrew Z80 computer. I'm at the sta…

> some long DIP headers (10 USD)

You're severely underestimating the cost of wire-wrap sockets. They're a low-demand item, so they're rather expensive; a few dollars for each socket is typical, and DIP40 sockets can get into the $10 range. (The sockets will cost more than most of the parts in them!)

Re: Let's Build a Video Card

#20
All of his breadboard videos are great, but I was hoping for a few more episodes in this one. You can't call it a video card if it doesn't plug into a computer, right?
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