VGA 640X480 256 Colors
megaionstorm
Posts: 178
Is there a possibility to create a 640X480 pixel and 256 color vga signal with the p8x32a ?
megaionstorm
Posts: 178
Comments
The standard VGA pinout is RrGgBbHV, so for 256 colors you'd need to move the sync signals to separate pins and modify VGA.spin to twiddle them via OUTA (and handle the slight timing differences).
The 256 colors would also be RRRGGGBB, while often "256 color" graphics use a 6 or 8 bit per color CLUT. Doing this on the Propeller would require a synchronized 3 cog display driver and a lot of effort.
But the bigger problem is RAM. The Propeller only has 32K of onboard RAM while a 640x480 8bpp bitmap requires 300K. Depending upon what is being displayed tiles are more memory efficient, but you are limited to 4 colors per tile.
Look at Bill Henning's -- Morpheus and drivers to it -- But I don't think it is MIT licensed -- at least Hardware.
640x480x256 is not possible, as it needs ~300KB of external ram being read at 25MB/sec, requiring approx. 30ns static memory and >100MHz Propeller clock speed, and would leave almost zero time for drawing into the frame buffer, so even with the above restrictions it would only be useful for a static display.
I do have a working 320x240x256 "gaming" mode driver for Morpheus that uses 640x480 VGA timing (so as far as the monitor is concerned it is 640x480)
My web hosting service is having issues, so all graphics/downloads are off line at the moment.
Sapieha is correct, the Morpheus design is not open source.
Kye's suggestion is an excellent one, an FPGA + memory is the way to go for high resolution 256 colors per pixel graphics (or a cheap ITX motherboard)
This would do the job too.
To bad, no way to download it !
What are you trying to make? The more information we have on what you want to do, the better the odds that we can help you.
Bill
The idea for my base concept is to create a circuit with 3 p8x32a.
One for the main work, one for soundfx and one for graphic vga output.
It should have a adapter for 2 nes gamepads and for microSD.
Speech synthesis through a speakjet ic.
I work with a breadboard p8x32a. 5MHz and pll16x.
I want add for the stereo sound output 2 tda amplifier, 10 W each.
Add the possibility for vga with 320X240 pixel and 256 colors.
As a base concept for my future ideas !
A second
I'd probably just use 64 colors though, in order to use the standard hardware.
(hopefully, I'll have time to try that out one day...)
If you used two of them on pins, P0..P7, similar to the way jazzed' modules are wired,
then I'd bet you could do 640x480.