How do i learn about video electronics? - Page 1
Forum section: electronics / beginners

author: Bullrider
author_rank: Newbie
timestamp: September 06, 2017, 06:14:30 pm
content: Hi! Nice to join this forum, my name is Paul, i live in Sweden and i think i'm an advanced beginner or something. The last couple of years i've learned about basic electronics, soldered some stuff together and collected a bunch of equipment, parts and books. While i do feel like most knowledge is within my reach if i'm willing to put in some work, there's one thing i'm not really sure about how to learn. If, for example, i would like to make a serial terminal for my z80 computer with composite video for an old tv(or vga or whatever, i'm interested in all different kinds), is there any good "tutorial like" sources i could use to learn about how you design that kind of stuff? Or maybe you at least know where i can get a good understanding of how different kinds of video works in theory. Thanks!

author: RoGeorge
author_rank: Super Contributor
timestamp: September 06, 2017, 06:26:24 pm
content: A serial terminal, a VGA monitor and a TV video are totally different.What Z80 computer do you have?

author: Bullrider
author_rank: Newbie
timestamp: September 06, 2017, 06:38:20 pm
content: I realise that tv video and VGA are very different things, but i'm interested in using either for a terminal because i have access to both old television sets and old computer screens, and i'm just generally interested in both and it would be nice if someone knows about some good reading. I have the rc2014, a barebone thing, not an old pc, i need to use an ftdi cable and a terminal emulator if i don't wanna buy a terminal module from the seller.

author: rstofer
author_rank: Super Contributor
timestamp: September 06, 2017, 06:46:20 pm
content: I had a long reply but I managed to dump it before I got it posted. So, I'll cut to the chase: Way back when, all of the logic for a text display terminal was incorporated in the Motorola 6845 chip and these are still available on eBay. Of course, there will be a lot of supporting hardware required like RAM and so on. But the hard part is done.For the RC2014 Z80 project, the author has a serial display terminal that uses a Raspberry PI Zero and he provides a custom micro-sd card that contains the terminal software for the PI. The slick thing is that it outputs HDMI or composite video. I have the board but I haven't assembled it yet. I'm having the delay of a lifetime in the delivery of the PI.http://rc2014.co.uk/modules/pi-zero-serial-terminal/

author: Bullrider
author_rank: Newbie
timestamp: September 06, 2017, 06:53:16 pm
content: Quote from: rstofer on September 06, 2017, 06:46:20 pmThanks! I didn't know about that chip specifically and will look it up. I know about that terminal and i may consider ordering it sometime, maybe i can analyze the software and learn something from that!

author: Markybhoy
author_rank: Regular Contributor
timestamp: September 07, 2017, 11:21:18 am
content: There is a book by Andew Lamothe called The Black Art of Video Game Console Design which I think covers designing vga output for a games console, might be worth a look.

author: Gyro
author_rank: Super Contributor
timestamp: September 07, 2017, 11:31:08 am
content: You might also search out a copy of Don Lancaster's 'TV Typewriter Cookbook'. It's pretty old but covers a lot of the basics.

author: Bullrider
author_rank: Newbie
timestamp: September 07, 2017, 09:28:50 pm
content: Those books seem really nice, thank you guys! Don Lancasters book was available as a pdf when i googled it in case someone other than me finds pleasure in such things, i've seen the ttl cookbook too before.

author: RoGeorge
author_rank: Super Contributor
timestamp: September 07, 2017, 11:17:30 pm
content: If you need some examples for a VT100 compatible serial monitor projects:https://hackaday.com/tag/vt100/

author: BubbaMc
author_rank: Contributor
timestamp: September 07, 2017, 11:41:53 pm
content: Quote from: Markybhoy on September 07, 2017, 11:21:18 amI was going to suggest this, it'll give a nice low level overview of a video system.OP - I'd strongly recommend staying away from composite, you won't be happy with the results. Instead look into analogue monochrome or RGB video (either 15khz or 31khz H Sync).Anyone can create a digital video output in this day and age, but where's the fun in that?

author: Bullrider
author_rank: Newbie
timestamp: September 08, 2017, 08:11:57 am
content: Quote from: BubbaMc on September 07, 2017, 11:41:53 pmI've actually ordered itQuote from: BubbaMc on September 07, 2017, 11:41:53 pmI'll look into that, this may be a dumb question but would i use RGB inputs to transfer a monochrome signal?Quote from: BubbaMc on September 07, 2017, 11:41:53 pmYeah, even though i'll learn about digital video there's just something exciting about analog video and crt screens!

author: helius
author_rank: Super Contributor
timestamp: September 08, 2017, 08:35:13 am
content: Don't forget Charles Poynton,A Technical Introduction to Digital Video(Wiley, 1996; ISBN 0-471-12253-X)Very good, demystifying treatment of color spaces, modulations, aspect ratios, etc.

author: helius
author_rank: Super Contributor
timestamp: September 08, 2017, 08:45:31 am
content: Quote from: Bullrider on September 08, 2017, 08:11:57 amIf the R, G, and B signals are output from a common DAC, (and it could be a 1-bit DAC for B&W!) the signal is effectively monochrome even if your monitor is color. If your monitor is in fact monochrome, then it will only connect to one of the color signals, usually green by convention.Composite is CVBS: Color, Video, Blanking, and Sync, all mixed together over a single wire. The reason it is hard to generate good composite is that these four signals occupy similar frequency bands and their phase relationship is critical to be able to be cleanly separated in the display. Just removing the Color signal makes it a lot easier (then you are left with Video (monochrome), Blanking, and Sync, which are all necessary in any analog system).

author: Bullrider
author_rank: Newbie
timestamp: September 08, 2017, 11:11:00 am
content: Quote from: helius on September 08, 2017, 08:35:13 amNice! Ordered it on ebay!Quote from: helius on September 08, 2017, 08:45:31 amThanks! That made things a bit more clear.