[sdiy] My 13 years old VGA Oscilloscope project on Youtube..

[Jean-Pierre Desrochers]

>That's really cool. Thanks for sharing this !

Thanks Jean !

 

>Could you explain what the pic do ? Is it for the Sync ?

Well you are right.
The PIC’s job is mostly to get all the VGA timing pulses accurate
with no jitters. It generates pulses for the video line width, Horizontal sync,

Vertical sync, Frame width, etc..  If you look at the available C code you will find
lots of delay loops and insertion of assembly codes for precise pulse widths like:

 

*************************

while(1)

  {

 

   for(line_counter=0;line_counter<600;line_counter++) // 600 DECI = 0x0258, 300 DECI = 0x012C

    {

     // delay 20 usec (D)

     // check line# here

     if(line_counter<0x0200)

      {

       delay_us(4);

       #asm

nop

nop

nop

       #endasm

      }

     else

      {

       delay_us(3);

       #asm

nop

nop

nop

nop

       #endasm

      }

Etc..

 

*************************

The rest of the schematic is for audio signal formatting to pulses
and color selection from a 7 positions rotary switch..

I do appreciate you had interest for this project.

Thanks again.



JP

 

 

 

De : Jean Bender [mailto:lofideadbeat at gmail.com] 
Envoyé : 7 mai 2018 16:41
À : Jean-Pierre Desrochers
Objet : Re: [sdiy] My 13 years old VGA Oscilloscope project on Youtube..

 

Wow !!

That's really cool. Thanks for sharing this !

Could you explain what the pic do ? Is it for the Sync ?

Thanks !

 

Le 7 mai 2018 10:23 PM, "Jean-Pierre Desrochers" <jpdesroc at oricom.ca> a écrit :

Hi list,

In 2015 I built a small VGA oscilloscope and then put it aside for a while..
(a long while...) Then Yesterday I rediscovered it by means of using it
along with an external
and complex audio waveform driving it.. (Using my DOTCOM modular as an audio
source)
I've been able to  create some weird VGA waveforms.. have a look here:
https://www.youtube.com/watch?v=VKMjb3CpOCE <https://www.youtube.com/watch?v=VKMjb3CpOCE&feature=youtu.be> &feature=youtu.be

This is an open source project so for anybody interested to go 
further or just build it, all the needed files are available here:
http://www.arcenson.com/projects/VGA_Oscilloscope/

Enjoy !!
By the way I just bought this morning an old VGA 15" 4:3 Samsung display 
For $10.00 to do some tests.. Really appreciate it !

JP


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