ATmega32 @ 8Mhz

[GoogleCodeExporter]

Hi

I got the atmega32 to run with arduino and now i would like to try the tvout 
library (I tested on other controllers).
I think the problem is the 8 Mhz (internel RC) clock. 8Mhz should be enough to 
create a PAL signal but I can't get it with this library. (See attachment)
To get rid of some compile errors, the only thing I had to change was the 
TIMSK1 to TIMSK and remove the tone library.
I am reading your code and saw the comment "only 16mhz right now!!!" in the 
file video_gen.cpp.
Would be great if you could give me some hints/advice how to get it run on 8Mhz.

Thanks and Regards
debain

Original issue reported on code.google.com by r...@group.li on 25 Feb 2011 at 8:10

Attachments:

• tvout.png

[GoogleCodeExporter]

well I wrote it to work with other clocks but have not been able to test it. 
The comment was targeted at that one render method and should actually work at 
lower clock speeds.

That said what resolution are you running? try something very low to start with 
say 56 pixels wide.

I have also never tried to get it working on the older devices (like your 32 or 
the 8). If I can find time soon I will try getting it working at 20mhz assuming 
it does then it will work at all other clock speeds as well(well fast enough 
ones anyway).

Original comment by mdmetzle...@gmail.com on 25 Feb 2011 at 10:52

[GoogleCodeExporter]

Thanks for reply, good to know that it could work with other clock speed. I 
already tried with other resolution but it doesn't work. I even can't see a big 
diffrent when changing the resolution (I thought the flickering lines should be 
bigger with lower resolution). I event tried to extend the assembler routine 
but no luck :)
I'm not able to localize the problem, could be the video properties, an 
assembler routine, sync, timer or other problem...
I'm trying this just for fun (and learning) because I have an atmega32! Not 
important, so forget about it. If I have the time and make progress I will post 
it here.
Thanks again

Original comment by r...@group.li on 26 Feb 2011 at 8:12

[GoogleCodeExporter]

Ok, some progress. I expected that the file hardware_setup.h is 
correct/tested...
For atmega32 the sync Pin is wrong, it should be:
//sync

#define PORT_SYNC   PORTD

#define DDR_SYNC    DDRD

#define SYNC_PIN    5

As you can see in the attachment, it is working much better...

Original comment by r...@group.li on 26 Feb 2011 at 9:33

Attachments:

• tvout2.png

[GoogleCodeExporter]

Ok running at 120x96 @8mhz wont work now, the 3cycle output method is indeed 
limited to 16mhz now.  However all the other routines are not clock speed 
dependent.

To sidestep this issue use a horizontal resolution of no more than 88.  Then if 
there are still issues with the image call TV.force_outstart(time) right after 
TV.begin(...) is called.  Selecting the correct value for time will require 
some trial and error, the defualt value is 12 for NTSC and 12.5 for PAL, it 
currently only takes integers however.

If you really want the higher resolions to work (up too 120 pixels @8mhz) 
modify void render_line3c().
Remove:
"cpi    %[hres],30\n\t"         //615
                "breq   skip0\n\t"
                "cpi    %[hres],29\n\t"
                "breq   jumpto1\n\t"
                "cpi    %[hres],28\n\t"
                "breq   jumpto2\n\t"
                "cpi    %[hres],27\n\t"
                "breq   jumpto3\n\t"
                "cpi    %[hres],26\n\t"
                "breq   jumpto4\n\t"
                "cpi    %[hres],25\n\t"
                "breq   jumpto5\n\t"
                "cpi    %[hres],24\n\t"
                "breq   jumpto6\n\t"
        "jumpto1:\n\t"
                "rjmp   skip1\n\t"
        "jumpto2:\n\t"
                "rjmp   skip2\n\t"
        "jumpto3:\n\t"
                "rjmp   skip3\n\t"
        "jumpto4:\n\t"
                "rjmp   skip4\n\t"
        "jumpto5:\n\t"
                "rjmp   skip5\n\t"
        "jumpto6:\n\t"
                "rjmp   skip6\n\t"
        "skip0:\n\t"
                "byteshift\n\t" //1             \\643
        "skip1:\n\t"
                "byteshift\n\t" //2
        "skip2:\n\t"
                "byteshift\n\t" //3
        "skip3:\n\t"
                "byteshift\n\t" //4
        "skip4:\n\t"
                "byteshift\n\t" //5
        "skip5:\n\t"
                "byteshift\n\t" //6
        "skip6:\n\t"

AND make sure there are only 16 calls byteshift macro calls.  This will hard 
limit this method to 120pixels but It "should" work at 8mhz.

Also I dont think set_hbi_hook will work at 8mhz just not enough time.

Original comment by mdmetzle...@gmail.com on 26 Feb 2011 at 2:26

[GoogleCodeExporter]

I can't get a higher resolution but figured out that since I changed the sync 
port it is working with 48x48 pixel! See attached video

Original comment by r...@group.li on 26 Feb 2011 at 4:09

Attachments:

• tvout.mp4