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Topic: The VideoBlaster Hi Resolution TVout platform (Read 10745 times) previous topic - next topic

janost

I'll see if I can make the colormode to work in tiled mode.

That would enable it to run on a 328.

janost

#91
Dec 21, 2013, 11:55 am Last Edit: Dec 21, 2013, 12:03 pm by janost Reason: 1
I also tried setting up 320x240 50Hz PAL in hope that the TV would display a mixed mode PAL sync and NTSC chroma color.
But it just got confused and displayed BW.

I guess PAL color requiers a 17.72MHz clock to get a 4.43MHz colorburst.

But 320x240 bitmapped mono and a mouse makes a nice desktop.

janost

#92
Dec 21, 2013, 06:56 pm Last Edit: Dec 21, 2013, 07:10 pm by janost Reason: 1
I also have a problem with the top of the screenlines driven to clamp intensity (overdrive and distorsion) on the TV.

I'm guessing it could be caused by the lack of an AC-coupling capacitor on the video output?

janost

#93
Dec 31, 2013, 07:26 pm Last Edit: Dec 31, 2013, 08:30 pm by janost Reason: 1
Here is the VideoBlaster code for 320x200 NTSC color bitmapped.
Its all a delicate work of timing so if you change anything there is no support.

I could do it tiled for the 328 but there is no Point in tiled Graphics and color or is there?
It still needs 14.318MHz Clock to show any color.

Happy New Year.

mrburnette


janost


+1
Thanks!  Great effort.

Ray


Thanks

If I did anything wrong, please let me know.

mrburnette

Quote
If I did anything wrong, please let me know.


Need to order the 14.318MHz crystal, first... Like 12.5 cents each from Newark... I probably need some stuff anyway  :D

Ray

janost

The code I put was actually the Bambino platform BIOS.

So you got the keyboard code as extra.

Never mind, it works anyway.

janost

This is the best you can do on the mega platform.
Simple and easy.

But you offer processingpower to the video image.

The clockratio is 1:4

With 14MHz you will have just over 3MHz left for the application.

mrburnette

#99
Dec 31, 2013, 11:05 pm Last Edit: Jan 01, 2014, 02:31 am by mrburnette Reason: 1
Quote
With 14MHz you will have just over 3MHz left for the application.


Perspective: ... Just over 3 MIPS left...

Ray

Added after reading forward 2 posts:
I Think this is indeed a great effort.  Not being a video-dude (I did work on tube TVs back in high school and did get zapped painfully by a green-screen mono monitor for an Apple II), I am impressed that the little AVR has any bandwidth left.
My 3 MIPs remark is A positive statement, 21% of the uC cycles are still available!  I have not compiled and profiled SRAM and Flash remaining, but with RISC chips my belief is that there is enough left here for some fun!

janost

That is the penelty you pay for doing it single chip.

janost

#101
Dec 31, 2013, 11:24 pm Last Edit: Jan 01, 2014, 07:03 am by janost Reason: 1
I Think I did a great eachievement getting composite color NTSC out of a single AVR chip?
And with that resolution, 320x200?

I cant do better :)

Anyone? do it better?

janost

Note that the chrin() function is mapped for a Scandinavian keyboard (shifted keys 0-9).
I could not get hold of a US/UK keyboard.

It was tough even finding a ps/2 keyboard.

They are all USB nowdays.

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