1. Spring 2007 1 EE 316 Computer Engineering Junior Lab LCD modules

2. Spring 2007 2 Topic  Liquid Crystal Display Modules

3. Spring 2007 3 Liquid Crystal Display (LCD) modules  Majority of the pixel-based alphanumeric LCD module uses the Hitachi HD44780 LCD controller chip.  Makers are: Densitron, Epson, Hewlett Packard, Optrex, or Sharp.  Most have 16, 20, 24, 32, or 40 characters by 1, 2, or 4 lines.  The LCD module we will use has a single line of 20 characters.  Each character is made of 5x7 dot matrix For more info: http://www.doc.ic.ac.uk/~ih/doc/lcd /

4. Spring 2007 4 LCD Display  To use these LCD module, you have follow the timing requirement very precisely. Pay attention to these times Important times http://www.mil.ufl.edu/imdl/handouts/lcd-faq.htm

5. Spring 2007 5 LCD Initialization  Before you use the LCD, you need to initialize the LCD with a very precise sequence of instructions.  Follow the intialization very accurately  Need to generate a sequence of 8-bit instructions with a minimum timing delay between two instructions  each instruction requires multiple steps raise the enable signal ‘E’, apply data or instruction, lower ‘E’, hold data or instruction  You may store these values in a PROM and apply to the LCD with correct times between two instructions.

6. Spring 2007 6 LCD Initialization Contd.  In this example at the end of the initialization the LCD is asked to return cursor to the home postion and clear previous display.  The LCD is then readied for display data (DD) input. The ASCII code for capital “D” is then sent to the LCD module Initialization begins here Initialization ends here LCD is ready for Display data input ASCII 0x44 = D

7. Spring 2007 7 ASCII code

8. Spring 2007 8 References  http://www.doc.ic.ac.uk/~ih/doc/lcd/ http://www.doc.ic.ac.uk/~ih/doc/lcd/  http://www.mil.ufl.edu/imdl/handouts/lcd-faq.htm http://www.mil.ufl.edu/imdl/handouts/lcd-faq.htm