Well, dont know if this helps at all, but here is how I did it with a 16 segment 10 character display.

I created a word size variable for the 16 segments. There was a look up table to determine which segments to light. Lets say that variable is seg

Then I had 10 bits for the grids, so lets say that was named grid. since it is more than 8 bits I also made that a word variable

So, to shift out my code I used:

Shiftout data,clk,mode [seg/16,grid/16]

Now to make this more applicable lets say I had a VFD with 20 characters on a 10x2 grid. I could name the first 10 grids grid1 and the 2nd 10 grid2

shiftout data,clk,mode [seg/16,grid1/16,grid2/16]

That shifts out a total of 48 bits.


My problem is figuring out how to get the proc to do other tasks while its still shifting out data. I cant recall the whole code right off but if I recall because the pic was doing all the character generation even with it doing nothing but updating the display it would either be too dim or there would be too much flicker.