LCM BASIC TECH

   The first LCDs were composed of only the LCD panel. This left 
the drive circuitry to the customer. More recent developments
have combined the LCD panel with a PCB( printed circuit board)
containing the drive LSI. This is known as an LCD module, which
offers customers a more complete solution. There are two types
of LCD modules: character and graphic. The character module is
composed of 1 to 4 lines of 16 to 40 character blocks having
5 x 7 dots plus cursor. Each character block is addressed 
separately and can form alphanumeric characters and a limited
number of symbols. Graphic modules provide users with a greater
degree of flexibility. They are composed of pixels arranged in
rows and columns. Each pixel can be addressed individually for
text, graphics or any combination of the two. An LCD controller
IC (intergrated circuit) is required to operate the graphic LCD.
Some models feature the controller chip built into the module.
See the Graphic Module Section for details. Tecdis dot matrix
character LCD modules are offered in a variety of sizes and 
configurations. Character modules are organized in blocks of
5 x 7 dots. This allows them to display characters to 4 lines 
of 40 characters. Each model is STN (FSTN) fluid for enhanced 
viewing characteristics. Standard TN fluid is available, but is
not recommended for new designs due to its limited contrast and 
viewing angle. EL or LED backlighting is an option for most models.
Character modules contain a built-in HD44780 controller chip that 
allows the LCD module to receive data directly from a 4-bit or 8-bit
microprocessor or microcontroller. The HD44780 has 192 character
patterns in the character generator (CG) ROM. Also available is
user-definable CG RAM, which allows the user to program up 
to 8 characters.