Its funny because the scrolling text is the easiest part of this project. I see your using the MAX6952 .. first thing is to get a copy of data sheet;
**broken link removed**
the way this device works is mainly to show steady characters. you can scroll easy if you just change the start of the string for each send like if you have the string HELLO
Send HELLO
Send ELLO
Send LLO
Send LO
Send O
Now its best to have a buffer. This way you know the length of the strings with a simple loop. Its easy if you simply let the last char in the string be 0x00 this way you have a endpoint. so if you have a buffer of 16 chars aka bytes then you can have a string like
H, E, L, L, O, 0x00,0,0,0,0,0,0,0,0,0,0
and make a loop to determine the len place the len in a var then dipsplay the string to the max6952 from start 0 then start at pos 1 then 2 until you reach the len var,
Hope that makes sense. I cant write the whole code for you tho.