The typical character mode LCD with a controller of the HD44780 ilk is strictly limited to 8 custom symbol designs at any one time. It is of course possible to utilize any of these 8 symbols on the display at any character position. Thus the display could show more than one of say symbol #0.

It is also possible to make up a user interface that utilizes more than 8 total symbols as long as only 8 are required at any one time. In this case you dynamically load the CGRAM with the character symbols needed for the current display. Here is a link that shows one application that works like this wherein a total of ten symbols are required but only two at a time are needed.

I have also used this scheme to display the likes of a battery meter on one line of an 8x4 display.

For more symbols then youu need to start looking at bitmapped graphics LCD's. Visit this page to look at low level work for displaying fonts and symbols on to graphics LCDs.

Michael Karas