The potential problem with the address pin was a problem. Not with the PCB, but with the FPGA module. One pin is stuck low. 🙁 Fortunately I had another one. Using that one there were no repeating random pixels! 🙂
Yesterday I worked hard to solve a really strange problem with the graphics. It turned out I just wasn’t finished thinking when I wrote the Verilog code. I tested my theory tonight and…. tadaa! No more strange graphic problems!
“Sprites” are still only white 16×16 pixel squares. These are the next step.
I drew two thick lines on the top bitmap. Behind the top bitmap the sprites are displayed, and behind the sprites there are two more bitmaps with one dark stripe each. Not that visible in the video, you will have to look closely. Also testing the separate X and Y offsets for the bitmaps, as you can see. 😉
Next step is to look at the sprites. After that I have to re-work the design of the main state machine. There are some serious optimizations needed to make this work without issues… When that is done I will add the color decoder.