The mikroC PRO for PIC provides a library for communication with Lcds (with HD44780 compliant controllers) through the 4-bit interface. An example of Lcd connections is given on the schematic at the bottom of this page.
External dependencies of Lcd Library
The following variables must be defined in all projects using Lcd Library :
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Description :
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Example :
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extern sfr sbit LCD_RS:
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Register Select line.
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sbit LCD_RS at RB4_bit;
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extern sfr sbit LCD_EN:
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Enable line.
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sbit LCD_EN at RB5_bit;
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extern sfr sbit LCD_D7;
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Data 7 line.
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sbit LCD_D7 at RB3_bit;
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extern sfr sbit LCD_D6;
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Data 6 line.
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sbit LCD_D6 at RB2_bit;
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extern sfr sbit LCD_D5;
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Data 5 line.
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sbit LCD_D5 at RB1_bit;
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extern sfr sbit LCD_D4;
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Data 4 line.
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sbit LCD_D4 at RB0_bit;
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extern sfr sbit LCD_RS_Direction;
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Register Select direction pin.
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sbit LCD_RS_Direction at TRISB4_bit;
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extern sfr sbit LCD_EN_Direction;
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Enable direction pin.
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sbit LCD_EN_Direction at TRISB5_bit;
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extern sfr sbit LCD_D7_Direction;
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Data 7 direction pin.
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sbit LCD_D7_Direction at TRISB3_bit;
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extern sfr sbit LCD_D6_Direction;
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Data 6 direction pin.
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sbit LCD_D6_Direction at TRISB2_bit;
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extern sfr sbit LCD_D5_Direction;
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Data 5 direction pin.
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sbit LCD_D5_Direction at TRISB1_bit;
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extern sfr sbit LCD_D4_Direction;
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Data 4 direction pin.
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sbit LCD_D4_Direction at TRISB0_bit;
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Library Routines
- Lcd_Init
- Lcd_Out
- Lcd_Out_Cp
- Lcd_Chr
- Lcd_Chr_Cp
- Lcd_Cmd
Lcd_Init
Prototype
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void Lcd_Init();
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Returns
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Nothing.
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Description
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Initializes Lcd module.
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Requires
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Global variables:
- LCD_D7: Data bit 7
- LCD_D6: Data bit 6
- LCD_D5: Data bit 5
- LCD_D4: Data bit 4
- LCD_RS: Register Select (data/instruction) signal pin
- LCD_EN: Enable signal pin
- LCD_D7_Direction: Direction of the Data 7 pin
- LCD_D6_Direction: Direction of the Data 6 pin
- LCD_D5_Direction: Direction of the Data 5 pin
- LCD_D4_Direction: Direction of the Data 4 pin
- LCD_RS_Direction: Direction of the Register Select pin
- LCD_EN_Direction: Direction of the Enable signal pin
must be defined before using this function.
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Example
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// Lcd pinout settings
sbit LCD_RS at RB4_bit;
sbit LCD_EN at RB5_bit;
sbit LCD_D7 at RB3_bit;
sbit LCD_D6 at RB2_bit;
sbit LCD_D5 at RB1_bit;
sbit LCD_D4 at RB0_bit;
// Pin direction
sbit LCD_RS_Direction at TRISB4_bit;
sbit LCD_EN_Direction at TRISB5_bit;
sbit LCD_D7_Direction at TRISB3_bit;
sbit LCD_D6_Direction at TRISB2_bit;
sbit LCD_D5_Direction at TRISB1_bit;
sbit LCD_D4_Direction at TRISB0_bit;
...
Lcd_Init();
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Lcd_Out
Prototype
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void Lcd_Out(char row, char column, char *text);
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Returns
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Nothing.
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Description
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Prints text on Lcd starting from specified position. Both string variables and literals can be passed as a text.
Parameters :
- row: starting position row number
- column: starting position column number
- text: text to be written
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Requires
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The Lcd module needs to be initialized. See Lcd_Init routine.
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Example
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// Write text "Hello!" on Lcd starting from row 1, column 3:
Lcd_Out(1, 3, "Hello!");
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Lcd_Out_Cp
Prototype
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void Lcd_Out_Cp(char *text);
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Returns
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Nothing.
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Description
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Prints text on Lcd at current cursor position. Both string variables and literals can be passed as a text.
Parameters :
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Requires
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The Lcd module needs to be initialized. See Lcd_Init routine.
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Example
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// Write text "Here!" at current cursor position:
Lcd_Out_Cp("Here!");
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Lcd_Chr
Prototype
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void Lcd_Chr(char row, char column, char out_char);
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Returns
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Nothing.
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Description
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Prints character on Lcd at specified position. Both variables and literals can be passed as a character.
Parameters :
- row: writing position row number
- column: writing position column number
- out_char: character to be written
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Requires
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The Lcd module needs to be initialized. See Lcd_Init routine.
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Example
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// Write character "i" at row 2, column 3:
Lcd_Chr(2, 3, 'i');
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Lcd_Chr_Cp
Prototype
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void Lcd_Chr_Cp(char out_char);
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Returns
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Nothing.
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Description
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Prints character on Lcd at current cursor position. Both variables and literals can be passed as a character.
Parameters :
- out_char: character to be written
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Requires
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The Lcd module needs to be initialized. See Lcd_Init routine.
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Example
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// Write character "e" at current cursor position:
Lcd_Chr_Cp('e');
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Lcd_Cmd
Prototype
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void Lcd_Cmd(char out_char);
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Returns
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Nothing.
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Description
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Sends command to Lcd.
Parameters :
- out_char: command to be sent
Note : Predefined constants can be passed to the function, see Available Lcd Commands.
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Requires
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The Lcd module needs to be initialized. See Lcd_Init table.
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Example
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// Clear Lcd display:
Lcd_Cmd(_LCD_CLEAR);
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Available Lcd Commands
Lcd Command
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Purpose
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_LCD_FIRST_ROW
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Move cursor to the 1st row
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_LCD_SECOND_ROW
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Move cursor to the 2nd row
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_LCD_THIRD_ROW
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Move cursor to the 3rd row
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_LCD_FOURTH_ROW
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Move cursor to the 4th row
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_LCD_CLEAR
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Clear display
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_LCD_RETURN_HOME
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Return cursor to home position, returns a shifted display to its original position. Display data RAM is unaffected.
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_LCD_CURSOR_OFF
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Turn off cursor
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_LCD_UNDERLINE_ON
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Underline cursor on
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_LCD_BLINK_CURSOR_ON
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Blink cursor on
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_LCD_MOVE_CURSOR_LEFT
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Move cursor left without changing display data RAM
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_LCD_MOVE_CURSOR_RIGHT
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Move cursor right without changing display data RAM
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_LCD_TURN_ON
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Turn Lcd display on
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_LCD_TURN_OFF
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Turn Lcd display off
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_LCD_SHIFT_LEFT
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Shift display left without changing display data RAM
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_LCD_SHIFT_RIGHT
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Shift display right without changing display data RAM
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Code
// LCD module connections
sbit LCD_RS at RB4_bit;
sbit LCD_EN at RB5_bit;
sbit LCD_D4 at RB0_bit;
sbit LCD_D5 at RB1_bit;
sbit LCD_D6 at RB2_bit;
sbit LCD_D7 at RB3_bit;
sbit LCD_RS_Direction at TRISB4_bit;
sbit LCD_EN_Direction at TRISB5_bit;
sbit LCD_D4_Direction at TRISB0_bit;
sbit LCD_D5_Direction at TRISB1_bit;
sbit LCD_D6_Direction at TRISB2_bit;
sbit LCD_D7_Direction at TRISB3_bit;
// End LCD module connections
char txt1[] = "Embedded";
char txt2[] = "Projects";
char txt3[] = "Lcd 4 bit";
char txt4[] = "Example";
char i; // Loop variable
void Move_Delay() { // Function used for text moving
Delay_ms(500); // You can change the moving speed here
}
void main(){
Lcd_Init(); // Initialize LCD
Lcd_Cmd(_LCD_CLEAR); // Clear display
Lcd_Cmd(_LCD_CURSOR_OFF); // Cursor off
Lcd_Out(1,6,txt3); // Write text in first row
Lcd_Out(2,6,txt4); // Write text in second row
Delay_ms(2000);
Lcd_Cmd(_LCD_CLEAR); // Clear display
Lcd_Out(1,1,txt1); // Write text in first row
Lcd_Out(2,5,txt2); // Write text in second row
Delay_ms(2000);
// Moving text
for(i=0; i<4; i++) { // Move text to the right 4 times
Lcd_Cmd(_LCD_SHIFT_RIGHT);
Move_Delay();
}
while(1) { // Endless loop
for(i=0; i<8; i++) { // Move text to the left 7 times
Lcd_Cmd(_LCD_SHIFT_LEFT);
Move_Delay();
}
for(i=0; i<8; i++) { // Move text to the right 7 times
Lcd_Cmd(_LCD_SHIFT_RIGHT);
Move_Delay();
}
}
}
