EE 316 Computer Engineering Junior Lab

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EE 316 Computer Engineering Junior Lab

• LCD modules

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Topic

• Liquid Crystal Display Modules

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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
/
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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
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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.

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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 ends here
Initialization begins here
ASCII 0x44 D
LCD is ready for Display data input
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ASCII code
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References

• http//www.doc.ic.ac.uk/ih/doc/lcd/
• http//www.mil.ufl.edu/imdl/handouts/lcd-faq.htm