16x2 LCD Theory
The 16x2 LCD module that we will use runs off of the HD44780 interface controller. This means that our pic will not control the lcd directly, instead it will send commands to this 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:
Click To Enlarge
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.
For the system we are designing, we will use the 4-bit mode which means the function set must be the first command sent to LCD module. After that, all commands should be sent in dual 4-bit sends.
The 16x2 LCD module that we will use runs off of the HD44780 interface controller. This means that our pic will not control the lcd directly, instead it will send commands to this 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:
Click To Enlarge
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.
For the system we are designing, we will use the 4-bit mode which means the function set must be the first command sent to LCD module. After that, all commands should be sent in dual 4-bit sends.