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How to expand VGA Rows and column ? — Parallax Forums

How to expand VGA Rows and column ?

CameronMCameronM Posts: 57
edited 2010-07-11 06:52 in Propeller 1
·Hi, I was wounding if there is any way to expand the VGA resolution on the VGA object? I would like to do this if possible without using a different object.

Thank you,

CameronM

Post Edited (CameronM) : 7/11/2010 4:19:03 AM GMT

Comments

  • Mike GreenMike Green Posts: 23,101
    edited 2010-07-11 01:40
    You can't increase the VGA resolution in the VGA object significantly. There are a variety of other objects with higher resolution that work by using more than one cog at a time to generate the video. They're all text-only video drivers because there just isn't enough memory in the Propeller to act as a graphics display buffer beyond 512 x 256 pixels. It's possible to use most of the Prop's I/O pins to connect external RAM for use as a graphics display buffer. Have a look at Bill Henning's Morpheus board and his video drivers for examples.

    If you're just interested in text, have a look at the higher resolution drivers in the Object Exchange. They work mostly by using 2 or 4 cogs to handle 4 or 2 scan lines each while one of the cogs is outputting the scan line information.

    Post Edited (Mike Green) : 7/11/2010 1:45:46 AM GMT
  • CameronMCameronM Posts: 57
    edited 2010-07-11 04:27
    Thank you for the response,·but what·i meant to say·was·how·could i change the amount of·rows and columns for the VGA object? I am only able to use a little over half of my screen.

    Thank you,
    CameronM
  • Mike GreenMike Green Posts: 23,101
    edited 2010-07-11 05:18
    You're really talking about two very different things. The number of rows and columns is not very changeable for the reasons I mentioned. How they display on the screen is different. If you can't get the information to fill the screen, you may need to change some of the VGA timing information. Please give some information on what Propeller board you're using, the system clock frequency, some information on the display you're using including the resolution and horizontal and vertical scan frequencies.
  • CameronMCameronM Posts: 57
    edited 2010-07-11 06:52
    I am using the propeller edu kit-40 pin DIP version. The system clock frequency is at 80MHz. I am using the acer AL1916W, the screen resolution is 1440x900, Horizontal 30kHz~82kHz x Vertical 56Hz ~76 Hz . The program I am using is a modified version of VGA_Demo, so both the demo and my program are running at i guess you could call it in widescreen. But this is the only demo that is not running at full screen all the other VGA ones are running fine.
    Here is a link to the manual if i did not provide enough info, page 8 has the specs.
    ftp://ftp.work.acer-euro.com/monitor/lcd/manuals/al1916w/user/English.pdf
    I have one other question for the VGA out it is recommended that you use 240 Ohm resistor would I be able to get away with using a 220 Ohm resistor in place?

    Thank You,

    CameronM

    Post Edited (CameronM) : 7/11/2010 7:08:35 AM GMT
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