is there a simple way to get composite sync from the VGA driver?

CJ

I have this nice little 320x240 vga lcd, the only part of the equation I am missing at the moment is the composite sync that it needs

anyone know how to get it from the VGA driver?

Thanks

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Bean

Not sure about VGA, but I think NTSC composite sync if just an XOR of the VSync and HSync signals.

Bean.

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Franz Achatz

do you have a data-sheet from the 320x240 monitor ???

Franz

CJ

I have been able to find the physical specs but not the signal requirements, another site has some info for using it with a pc, but I really don't have anything more to go on

http://www.mp3car.com/vbulletin/lcd-display/69538-sharp-casio-gamecube-display.html

I got it to show some info using vga text, but nothing more than distorted video, any hints for adjusting the front porch back porch etc??

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Post Edited (CJ) : 8/6/2007 6:02:38 PM GMT

CJ

I am closing in on the proper timings now, got almost stable text from the highres text object

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Franz Achatz

Cj,

this is a Sharp 6 Inch. Should be easy to get it up and running at the Propeller VGA Port.
You have to take care about Pin7.
See my Thread for more infos:

http://forums.parallax.com/forums/default.aspx?f=25&m=206606

But you have to do some work for the right timing and Param-settings !!!!!
A scop connected to H-Sync helps by testing it out (15- 16 KHZ or so).

br
Franz

CJ

Franz, how did you go about combining the sync signals?

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deSilva

Exactly as he showed in his posting..

CJ

didn't spot that at first, thanks

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Franz Achatz

CJ,

i can see that your composite sync signal is connected to pin 7.
Just take a resistor valued to 1k and a Diode (1N4148 or so).
Connect the resistor to Pin7 and the open end gives you VSync to the Propeller.
Connect the Diode to Pin7 (anode Pin7) and Kathode gives you HSync to the Propeller.
That's all, the rest is your work (optimize timing etc....).

br
Franz

CJ

thanks, I think I am going to have to put together a board, as this unit seems to be finicky about capacitance on the sync line

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CJ

finally got the timings sorted, it is a very sweet little text display 40x20 with 64 colors



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Post Edited (CJ) : 8/6/2007 10:22:51 PM GMT

Franz Achatz

CJ,

very nice done

I just discovered that in this sits a high quality Sharp TFT Display with 480 x 234 pix:

http://cgi.ebay.de/Playstation2-Joytech-7-TFT-Monitor-Reisepaket-NEU_W0QQitemZ110153851890QQihZ001QQcategoryZ14259QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

Its exactly the same (LQ070) i am playing with at my propeller VGA port.

Franz

Harrison.

I got a quick question: How on earth did you guys calculate the front/back porch and all the various timings? I spent probably 2 days trying to get a laptop LCD to work, but then again it is a digital 9 bit rgb lcd with pixel dot clock. I even made an extensive excel spreadsheet using a sharp app note on controlling their TFT lcds.

I could not get the correct timings for it, which almost drove me insane. I settled on using a 17 inch computer monitor instead since it didn't seem worth the trouble.

CJ

Harrison, I will fill you in when I get back, but right now, lets leave it at a strong electronics intuition and wikipedia to fill me in on what each item meant


be back in about 20

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CJ

For my LCD I started with the pixel rate divided by the desired horizontal frequency to get pixels per line, if it is a large amount over your native pixels then lower your rate
PR / HF = PPL

then I padded the horizontal front porch, back porch, and sync to fill the line
HFP + HBP + HSYNC = PPL

for the Verticals, I just experimented, using Ctrl+F10 to try various settings



now that I am writing this, I think I may have been lucky, didn't know what almost all of these settings meant before today

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