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Controlling a Computer screen — Parallax Forums

Controlling a Computer screen

robotboyrobotboy Posts: 30
edited 2012-12-05 18:52 in Propeller 1
Hi guys, Im a beginner in propeller and I was wondering how people can control a computer screen using a propeller chip. I have a Quickstart I would like to use for this project. If you guys could help me and maybe give me a little code to play with that would be awesome!




Aarons Robotics

Comments

  • CircuitsoftCircuitsoft Posts: 1,166
    edited 2012-11-06 18:47
    The easiest option is probably the Quick VGA+. The circuit is pretty simple and you could probably build it yourself, but the QuickVGA isn't too expensive.
  • kuronekokuroneko Posts: 3,623
    edited 2012-11-06 18:56
    @robotboy: You might want to check out Jeff's propeller powered place.
  • robotboyrobotboy Posts: 30
    edited 2012-11-06 19:06
    Ok I'll check out the links! Thanks!
  • robotboyrobotboy Posts: 30
    edited 2012-11-06 20:24
    Now how do I find out how to use Jeff's board?
  • Oldbitcollector (Jeff)Oldbitcollector (Jeff) Posts: 8,091
    edited 2012-11-06 20:51
    robotboy wrote: »
    Now how do I find out how to use Jeff's board?

    The VGAplus board is configured much like the "Demoboard" in regard to VGA, Keyboard, and audio connections. Most any of the common programs which work with it will also work with VGAplus. In addition SRAM, Wii, and SD module sockets are available. While there wasn't room for TV video out, the pins 12..14 are broken out on the side for easy connection of TV.

    Jeff
  • robotboyrobotboy Posts: 30
    edited 2012-11-07 06:29
    Oldbitcollector I sent you a PM.
  • robotboyrobotboy Posts: 30
    edited 2012-11-30 12:22
    Ok i have a screen and a key board, and i dont know how to hook them up to use them... is there and semantics? also how do you program with a screen, samples? and how do i read witch buttons pressed on the key board? if you can help that would be great!
  • Mike GreenMike Green Posts: 23,101
    edited 2012-11-30 13:36
    If you look in the library that's installed when you install the Propeller Tool, you'll find both a PS/2 keyboard driver and several VGA display driver objects, one for graphics and one for text-only. They all come with demo programs and the comments in the source code are extensive. If you look in the Propeller Object Exchange, you'll find the same objects as well as others that may have specific features. The comments in the drivers and demo programs also show how to set the I/O pins up and what resistor values you'll need. You can use the Demo Board schematic for a model for the connections.

    See keyboard driver here.
    See VGA driver here or here.
    See VGA text-only driver here.

    There are all sorts of other VGA drivers available in the ObEx with various resolutions and features.
  • robotboyrobotboy Posts: 30
    edited 2012-12-01 06:06
    Cool... but do you know how to hook up the keyboard or Screen? Id like to make my own board.
  • prof_brainoprof_braino Posts: 4,313
    edited 2012-12-01 07:15
    robotboy wrote: »
    Cool... but do you know how to hook up the keyboard or Screen? Id like to make my own board.

    You should consider the prop demoboard if you don't already have a board wih a VGA connector. The demoboard is the "standard" for VGA connection. Look at the schematic for the demoboard. It will show you exactly how to do the circuit, I believe.
  • Duane DegnDuane Degn Posts: 10,588
    edited 2012-12-01 07:44
    robotboy wrote: »
    Cool... but do you know how to hook up the keyboard or Screen? Id like to make my own board.

    The schematics for the Propeller Demo board are in the Propeller Tool's "Help" section. The demo board has both vga and keyboard connections.

    The demo board doesn't use the optimal resistor values for its VGA connection. Phil has posted information about a better set of resistor values to use. If you need help finding the thread let us know. I bet one of us could find it for you.

    Using the resistors in the demo board schematic will work fine, the colors just wont have the range they would using Phil's values (all my boards use the demo board resistor values).

    Another VGA board option is the Propeller Protoboards. They have holes for VGA and PS/2 connectors (they use a stacked connector, Digi-Key has a pretty good price for this connector).

    Edit: I hadn't seen Prof_Braino's post.
  • PublisonPublison Posts: 12,366
    edited 2012-12-01 08:21
    Duane Degn wrote: »
    The demo board doesn't use the optimal resistor values for its VGA connection. Phil has posted information about a better set of resistor values to use. If you need help finding the thread let us know. I bet one of us could find it for you.

    Phil's thread is here:

    http://forums.parallax.com/showthread.php?135385

    I had to look it up just this week so I had it bookmarked.

    Another related thread: (Pertains to TV out resistors)

    http://forums.parallax.com/showthread.php?107596-Two-component-Video-DAC&highlight=Component
  • Oldbitcollector (Jeff)Oldbitcollector (Jeff) Posts: 8,091
    edited 2012-12-01 09:37
    @robotboy

    What are you trying to accomplish? There are many directions the VGAplus/Demoboard/Human Interface Board can go. Mike has given you some of the "tried and true" VGA drivers, and there are many more. The schematics for the VGAplus board are at http://www.propellerpowered.com/library (Schematics section). The schematics for a Demoboard are included in the "pull down" menu of the Propeller Tool itself. You'll find that all three products are using the same I/O pins for VGA and keyboard so most examples will be cross-compatible.

    Jeff
  • robotboyrobotboy Posts: 30
    edited 2012-12-01 10:34
    Ok, I found what i was looking for... http://www.parallax.com/Portals/0/Downloads/docs/prod/prop/PropellerDemoBd-RevG-Schem.pdf I will build it on a bread board and test it out :D
  • CircuitsoftCircuitsoft Posts: 1,166
    edited 2012-12-01 20:37
    Solderless breadboard? If so, it's not likely to work particularly well. They tend to not respond to high-frequency things very well at all.
  • potatoheadpotatohead Posts: 10,261
    edited 2012-12-02 08:43
    I've done video circuits on my breadboards. They are a bit flaky due to the potential for poor connections, but for TV / VGA it is not too big of a deal. Just keep connections short and trouble shoot loose or incomplete breadboard hookups. I like to coat thin component leads with solder to prevent this and have had very good results overall.

    Stick with a known good program to keep variables down, then once the circuit is performing well, start changing or writing new code.

    The basic rule for video is to make one change at a time so that troubleshooting remains sane.
  • localrogerlocalroger Posts: 3,451
    edited 2012-12-02 17:50
    I've done both TV and VGA second channels on a PPDB. It works fine. The only thing I've ever really had a breadboard issue with is delta-sigma ADC, which really doesn't work right with leads longer than an inch or so from the prop chip die.
  • rjo__rjo__ Posts: 2,114
    edited 2012-12-03 19:36
    Hold on there Robotboy... we all might be sending you down the wrong alley:)\

    Exactly what do you mean by control? Do you want the computer to do something on the screen in response to what you tell it to do from a Propeller?

    That's easy... but a different can of worms:)

    Rich
  • robotboyrobotboy Posts: 30
    edited 2012-12-05 18:52
    rjo__ wrote: »
    Hold on there Robotboy... we all might be sending you down the wrong alley:)\

    Exactly what do you mean by control? Do you want the computer to do something on the screen in response to what you tell it to do from a Propeller?

    That's easy... but a different can of worms:)

    Rich

    Well... I was going just hook up my screen to the propeller but.... I dont know how much I want to do it any more :p
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