Interfacing A PIC To LCD: Theory

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PIC -> LCD Interface Theory
           Luckily the interfacing is fairly straight forward with a processor to processor bus. Our pic will not control the lcd directly instead it will send commands to the on-board lcd controller, the HD44780. All the commands that we can send (there are only 11) to the controller are listed out in this chart:

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           Looking through the chart, there are two things to notice. (1) We can use either an 8-bit or 4-bit data bus for communication with the lcd interface. This is a great advantage because it lessens the amount of wires & i/o ports that we have to use. (2) We have to set it to display either 1 or 2 lines. These two things are done in the function set command.
           Most of these commands are rarely used, as you can imagine printing the characters is what happens most with the lcd.