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View Full Version : Needed: basic wisdom concerning the use of VGA



ElectricAye
03-17-2009, 04:37 AM
Hi all,

Newbie questions follow.....

I've been using a TV for displaying the data from my Propeller but I'm now considering using a VGA so I can get a better data display, etc.

Problem is, I can't find a basic description of how to use VGA. The VGA spin files have next to no comments (my usual complaint). All I need is something that says in human language,

When you want to show a number, do this...
When you want to display text, do this...
When you want to clear the screen, do the following.... etc.
You get the idea.

I don't know any assembly language, so I'm limited to SPIN.

Long story short, I need code that displays something along the lines of this...

Frequency1 = 32600 Hz
Temperature1 = -6 F
etc...

Also can anyone suggest what to use for a VGA screen that would make a nice replacement for a TV? Is there a common doo-hicky that costs less than $50 that can be picked up at surplus places, etc???

thanks for your inputs,
Mark


http://forums.parallax.com/images/smilies/smile.gif

Erik Friesen
03-17-2009, 04:55 AM
You can use vga_text exactly the same way you use tv_text. If you look at the propeller demo board and the way its basepin is used you should have little trouble.

MagIO2
03-17-2009, 05:07 AM
In the base directory of the propeller tool you find the VGA_TEXT.spin. If you click that and tick the summary radio-button in PT, you only see the functions. All starting with pub can be used. So, str prints a string, hex prints a hex-number. The parameter names give you an hint what's expected in the parameter. Only one which is not self-explaining is the out function.
Set the cursor to the out-function and click Full Source radio button again. Here the comment gives you a list of special characters.

In the library-folder you find a _demo for each Object which gives you an idea on how to use the stuff.

Kye
03-17-2009, 05:31 AM
Test mine out, it's fully commented and works as you would think it would.

http://forums.parallax.com/forums/default.aspx?f=25&m=335776

You can find it in that tread, just scroll down a few post.

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Nyamekye,

Mike Green
03-17-2009, 05:39 AM
The tv_text driver and the vga_text driver were written to be mostly interchangable. FemtoBasic uses a modified version of both of them to provide "drop-in" equivalence for everything but changing the display colors (since that's different between the two devices).

ElectricAye
03-17-2009, 08:19 AM
Mike Green said...
The tv_text driver and the vga_text driver were written to be mostly interchangable....


Thanks, Mike, that provides a starting point. And to Erik and MagIO2, too.

To Kye, I will try to have a look at what you've done. The idea that code is offered WITH comments is such a rare blessing. I'm a total non-EE noobie who struggles moronically with every iota of code and components that I add onto my Propeller. Generally speaking, I go through a 3 step process when wanting to put new features into my Propeller system. First, I go nuts because the OBEX code is usually so stripped down, I can't make any sense of it. My blood pressure shoots through the roof and I crash into a dark, brooding depression. Second, after being told that the OBEX code should be intuitively obvious to the most casual of observers, I have a total nervous breakdown, get insanely drunk, and drive my car over a cliff after eating a bottle of sleeping pills and drinking a gallon of chlorox. Days later, I awake in the hospital to find that the OBEX code isn't that hard to understand after all. The clouds clear, the body cast comes off, and somehow, by some miracle, I figure out what people are trying to tell me and eventually get the thing to work.

I tell you, being a Mech E in a world of EE's, it's tough. http://forums.parallax.com/images/smilies/shocked.gif