VGA Etch-A-Sketch

[JuggaloStoopid]

I am making a VGA Etch-a-Sketch for my class project. I must use a 16F877A for my pic chip, and must program it with ASM.

I am baseing my project of this VGA BOX

One thing that I think I will have some problems with is outputting to the screen.
I dont know how I would implement this. I am used to game programming for the computer and the way you would make something appear on the screen is set a pixel to what ever color you would like. I dont know if the PIC chip has enough memory to hold some kind of value for each pixel.

Then the other problem I am running into in my head, since the output to the screen has to be perfectly synced with the monitor, do I (or can I even) multi-task the chip to do my testing of the knobs, change the screen memory and all that. One way I can see it, is the screen refreshes at 60 frames a sec, and if I change the screen at every 2 refresh rates, that gives me some time to make all the changes I need.

If anyone has done something with VGA before or just know, any help will do...

 

[ClydeCrashKop]

Check Texas Instruments and others. I am sure there are video driver chips, maybe with memory. Or is that cheating?

 

[Pommie]

I am making a VGA Etch-a-Sketch for my class project. I must use a 16F877A for my pic chip, and must program it with ASM.

I am baseing my project of this VGA BOX

One thing that I think I will have some problems with is outputting to the screen.
I dont know how I would implement this. I am used to game programming for the computer and the way you would make something appear on the screen is set a pixel to what ever color you would like. I dont know if the PIC chip has enough memory to hold some kind of value for each pixel.

Then the other problem I am running into in my head, since the output to the screen has to be perfectly synced with the monitor, do I (or can I even) multi-task the chip to do my testing of the knobs, change the screen memory and all that. One way I can see it, is the screen refreshes at 60 frames a sec, and if I change the screen at every 2 refresh rates, that gives me some time to make all the changes I need.

If anyone has done something with VGA before or just know, any help will do...

The only thing that that VGA box can do is display preset patterns. It could not be used as the basis for an etch a sketch. If you have to use a 16 series chip then the simplest (maybe only) way to accomplish this is with a graphic LCD.

Mike.

 

[kchriste]

The site appears to be down right now, but what about adapting this to VGA:
**broken link removed**

 

[JuggaloStoopid]

ClydeCrashKop: I will find out tommarrow if its allowed. if so, does anyone know of a display chip that would work?

kchriste: I know of the rickard site, where I first started to get the idea for all this, a tv would work for my project too, so it dont have 2 be VGA.

Pommie: I think its possible, cant look at rickards site now, but he made tetris and pong with the 16f84, (I think its very simular but less memory as 16f877). He was able to do some kind of memory map to the screen, but not sure how? is there any reason you think this wont work?

 

[Pommie]

The problem with trying to do something like an Etch a Sketch is the resolution required. VGA is 640*480 = 300,000 pixels. If you make each of your large pixels 10*10 normal ones then this goes down to 64*48 = 3000 pixels. The 16F877 only has 368 bytes of memory. Going to the extreme used in the VGA box of 25 pixels across and running the pic at 20MHz you only have 5 instruction cycles per pixel.

I think it can be done at low resolution, but it's not easy.

Mike.

 

[Kryten]

Wouldnt it be possible (if using a VGA driver chip) to just have the PIC controll the point of the erch-a-sketch?

I mean to have the VGA driver to hold all the points where you have drawn and have like a "shake" button for erase the screen

 

[JuggaloStoopid]

I talked with the teacher today, and he didnt say anything about not being allowed to have a driver, so if you know of any that would work.

I am not too worried about color. I was just going to use solid red,green, & blue.
One Idea I had was to store 2 pixels in 1 file register. have each nibble store each pixel data. (On/Off, R, G, B).

Also if I want to do just grey & white, then I could store 4 pixels in 1 file register.

What do you guys think?