I'm trying to improve the graphics speed. I saw some guys using a 16 bit mode on the SPI interface on a arduino setup and investigated a bit and found the configuration for the LM4F SPI bus to set it to 16 bit. Made a quick test and the gain is great! It's easily seen in the videos.

For testing purpose I've added a few screen fills on the startup sequence, black/white/black...

8 bit:

16 bit:

I'll make some measurements to see how much it improves but it's visibly faster.

Now I have to solve some issues on the software as the images are arranged in 8 bits and making a direct assignment to 16 bits won't work. This is not a problem on black and white as they are all zeroes or all ones but on diferent colors that's not the case. I made some preliminary tests but didn't work. Have to work a bit more on this.

Edit 1: Color issues solved. So now images also run on 16bit mode.

Edit 2: Even faster speed as I reduced the cable length and was able to run the SPI at the max. allowed speed on the Stellaris of 25Mhz. With the longer cable setting I can only go up to 16Mhz. Will post a video of the differences.

Now, by my calculations, one full frame takes about 70ms. Fast enough... :)