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an other question about bitmap — Parallax Forums

an other question about bitmap

MazziniMazzini Posts: 58
edited 2011-08-08 10:14 in Propeller 1
Good Day,

my first time here,

I just started with Propeller and I ' am reading many stuff about it.
My pourpose is load an bitmap 400x256 pixel with 8 colors min ( 16 is the best) on TV Pal
I read here http://www.parallax.com/portals/0/help/P8X32A/QnaWeb/
but I'am not sure about what I understood.
so ask you , Can I load bmp 400x256 pixel 8/16 colors on TV Pal? ( edit : my board is Propeller C3 Rev A )
and If I'm not doing to many questions , what mean 1 pixel every byte ?

I read also info about video generation ( timing,hsync,vsync,burst) but there are too many info in my head.. so im a bit confused at moment :)

Mazzini
Italy (sry for bad english)

Comments

  • BaggersBaggers Posts: 3,019
    edited 2011-08-07 09:31
    Hi Mazzini, welcome to the forums :)

    The propeller has 32KB of internal HUB-RAM, and you're wanting 400x256 which is 102400 pixels, at 16 colours ( 4bit ) would be 51200 bytes, which is a lot more than 32KB.
    You would have to look at extra ram, but as the video generation alone is too confusing for you at the moment, let alone the complexity of adding external RAM into the mix.

    You would be better off starting with something simpler.

    Regards,
    Baggers.
  • MagIO2MagIO2 Posts: 2,243
    edited 2011-08-07 10:25
    Welcome, Mazzini!

    Depending on what you want to do, it might be an alternative to buy a LCD which has it's own internal RAM. Then the propeller simply has to read the BMP (makes sense to use a 32bit picture in this case) from SD card and send it to the LCD.

    You should tell a bit more about your goal.

    Cheers,
    MagIO
  • MazziniMazzini Posts: 58
    edited 2011-08-07 12:12
    Hi ,thank you

    yes you are right , it's hard for me at moment, but I will try explain my goal.
    I would like just load on TV this image:

    http://www.ivan.agliardi.it/2007/11/16/prove-tecniche-di-trasmissione/monoscopio-rai/ ( random link , I just googled "monoscope" )


    I will continue to study :) my goal is learn pasm
  • Peter JakackiPeter Jakacki Posts: 10,193
    edited 2011-08-07 19:10
    Hi Mazzini,

    Welcome to the best CPU forum there is, anywhere!

    The TV test image that you want to display is a perfect candidate for what is called a tiled bitmap image, that is each pixel only requires a single bit so 400x256 = 12.8KB. But wait! a single bit is monochrome, how do we get color? Then imagine the screen divided into little areas just like tiles and each of these tiles can have their own foreground and background color. Therefore even a 16x16 area would only require an extra byte to represent one of 16 colors for the foreground and likewise for the background. Analyze the monoscope image yourself but it looks like it could very easily work with this scheme.

    Various drivers exist in the OBEX and elsewhere in the forum. Baggers happens to be one of the main contributors in this regard, maybe he or someone else well qualified can comment on this possibility.
  • BaggersBaggers Posts: 3,019
    edited 2011-08-08 02:09
    Yes, that image ( although it has disappeared now ) would be a great candidate for using a tile map, and as you're goal is to learn PASM, you'd be better off starting with getting to grips with simpler PASM routines, than a complex display driver, then once you're competent enough with PASM then acquaint yourself with the TV display drivers, and once you know how it works, then you can have a go at making your own, to display your image, but I'd say that that is a long way off yet. :)
  • MazziniMazzini Posts: 58
    edited 2011-08-08 10:14
    thanks for the advice
    I'm writing some notes and i have a couple of questions to do but not here, I will do a new thread :D
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