Step 9: Big Number Clock on LCD
We will use custom characters to create big number fonts on the LCD, making it look much better.
The LCD datasheet talks about two RAM sections, DDRAM which is for "display data", meaning the text on display, and CGRAM, which is the "character generator" data, containing the custom font.
So during initialization of the LCD, we load up the CGRAM with some custom characters. The commands we need are the ones needed to set the CGRAM address, and then write to the CGRAM.
So what I've done is create several "block-like" characters, which can be arranged into numbers that are two lines high.
Please see the attached demonstration, it should cycle through the possible numbers for you.
The idea is from http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1213319639