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Topic: Arduino UNO COLOUR NTSC Output with AD725 - Bad colours issue... (Read 150 times) previous topic - next topic

axxel

Dear friends.

I'm trying to make an NTSC color pattern generator based on Arduino UNO full stock with stock 16mhz oscilator.

The TVout Library looks great and works with interrupts, but the problem I tried to understant it, there is a lot of assembler code, and I don't understand nothing at the assembler code... It is very difficult for me to mod the library to get a colour output... due to my lack of assembler language...

So I made a RGB + Sincro generator with a "raw method" and more easy to understand code based on this thread:

https://forum.arduino.cc/index.php?topic=43085.0

I modded it a little bit to have R, G and B channels.





With some modifications to have an RGB output here is the code:

You can download the code in the attachment.

If you want this code run, please upload and compile with Arduino IDE 1.0.6. With the more recents one like 1.8, it will not work, another problem I have to FIX later... This should be due to the NOP; asm instruction... I don't know...

I use this diagram to connect the AD725:



The problem are the colours.

Instead of THIS,



I have this:



The problem is not with pure R pur G or pure B, the problem is when I mix for example blue and red, as you can see instead of pink, I have a full-red...
The red looks pale red.
The yellow looks pale green.
The green doesn't look... green but light blue...
The white is not white but like gray...

I loaded the game toorum quest 2.

http://petenpaja.blogspot.com/2013/11/toorums-quest-ii-retro-video-game.html

I have the same problems...

So I think this is an issue with the AD725 RGB to PAL/NTSC encoder... I tried to change the resistors from the arduino to the AD725... No results.

I think this issue is with the PIN 12 YTRAP... But I'm not sure...

If someone had experience with the AD725 chip it can be great for hepling me there!

Best regards...

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