I built a VGA generator on a breadboard, with a design that borrows from the now-famous Ben Eater video.
I changed some things up. First I targeted a 320x240 resoltuion (derived from 640x480) instead of 200x150 (derived from 800x600). This required a slightly faster pixel clock (~12.5875mhz, derived from a 25.175mhz oscillator, instead of a 10mhz (derived from 40mhz) as used in the original video.) I also used CMOS chips instead of TTL ones. I found that the clock speed was too fast for my build, and had to reduced the horizontal resolution in half. I can use it to draw clean horizontal lines becouse they are derived from the vertical counter. It does not draw clean vertical lines becouse they are derived from the horizontal counter, which is running at 800 times the speed of the vertical one. I am happy I got a signal out of it, but am disappointed that I probably won't be able to draw bitmaps from it.
I original wanted to build a video card with acceleration for 2D bitmap graphics, however, it seems like it would require something like a CPLD and a custom PCB, and IDK if I want to invest more money into it.
I changed some things up. First I targeted a 320x240 resoltuion (derived from 640x480) instead of 200x150 (derived from 800x600). This required a slightly faster pixel clock (~12.5875mhz, derived from a 25.175mhz oscillator, instead of a 10mhz (derived from 40mhz) as used in the original video.) I also used CMOS chips instead of TTL ones. I found that the clock speed was too fast for my build, and had to reduced the horizontal resolution in half. I can use it to draw clean horizontal lines becouse they are derived from the vertical counter. It does not draw clean vertical lines becouse they are derived from the horizontal counter, which is running at 800 times the speed of the vertical one. I am happy I got a signal out of it, but am disappointed that I probably won't be able to draw bitmaps from it.
I original wanted to build a video card with acceleration for 2D bitmap graphics, however, it seems like it would require something like a CPLD and a custom PCB, and IDK if I want to invest more money into it.