tg_4bitlcd.c

嵌入式LCD驱动程序的实现top01_pac01

/*                                      HIDE   -> Cursor invisible  */
/*------------------------------------------------------------------*/
/* Returnvalue : none                                               */
/*------------------------------------------------------------------*/
/* History     : 06/99    V1.0 Basic routine                        */
/*               09/99    V1.1 Calculation of control modified      */
/*                             (because of compiler otim. bug)      */
/*                                                                  */
/********************************************************************/
void control_LCD(unsigned char dsp,unsigned char blink,unsigned char cursor)
{
unsigned char control;  // variable to generate instruction byte

control = (0x08 + blink + cursor + dsp); // Cursor control

EA = 0;                 // Disable all interrupts
LCD_RS = CTRL_REG;      // Switch to instruction register
// Set LCD_DATA to high nibble of Display On/Off Control
LCD_DATA = (LCD_DATA&0x0F)|0x00;
LCD_E = 1; LCD_E = 0;   // Write data to display
// Set LCD_DATA to lower nibble of Display On/Off Control
LCD_DATA = (LCD_DATA&0x0F)|((control<<4)&0xF0);
LCD_E = 1; LCD_E = 0;   // Write data to display
EA = 1;                 // Enable all interrupts

delay(4);               // Wait 400祍

return;
}


/********************************************************************/
/* Function    : gotoxy(x,y)                                    SUB */
/*------------------------------------------------------------------*/
/* Description : Sets the write position of the LCD display         */
/*                                                                  */
/*                 (1,1)         (16,1)                             */
/*                   |              |                               */
/*                   ################   -> line 1                   */
/*                   ################   -> line 2                   */
/*                   |              |                               */
/*                 (1,2)         (16,2)                             */
/*------------------------------------------------------------------*/
/* Author      : Thorsten Godau  NT8                                */
/*------------------------------------------------------------------*/
/* Input       : unsigned char x    -> x position (horizontal)      */
/*               unsigned char y    -> y position (vertical)        */
/*------------------------------------------------------------------*/
/* Returnvalue : none                                               */
/*------------------------------------------------------------------*/
/* History     : 06/99    V1.0 Basic routine                        */
/*                                                                  */
/********************************************************************/
void gotoxy(unsigned char x,unsigned char y)
{

EA = 0;                         // Disable all interrupts
LCD_RS = CTRL_REG;              // Switch to instruction register
// Set LCD_DATA to high nibble of position table value
LCD_DATA = (LCD_DATA&0x0F)|((LOCATION[y-1][x-1])&0xF0);
LCD_E = 1; LCD_E = 0;           // Write data to display
// Set LCD_DATA to lower nibble of position table value
LCD_DATA = (LCD_DATA&0x0F)|(((LOCATION[y-1][x-1])<<4)&0xF0);
LCD_E = 1; LCD_E = 0;           // Write data to display
EA = 1;                         // Enable all interrupts

delay(4);                       // Wait 400祍

return;
}


/********************************************************************/
/* Function    : clrscr()                                       SUB */
/*------------------------------------------------------------------*/
/* Description : Clears LCD display, and sets position to (1,1)     */
/*------------------------------------------------------------------*/
/* Author      : Thorsten Godau  NT8                                */
/*------------------------------------------------------------------*/
/* Input       : none                                               */
/*------------------------------------------------------------------*/
/* Returnvalue : none                                               */
/*------------------------------------------------------------------*/
/* History     : 06/99    V1.0 Basic routine                        */
/*               09/99    V1.1 Timing correction                    */
/*                                                                  */
/********************************************************************/
void clrscr(void)
{
 
EA = 0;                         // Disable all interrupts
LCD_RS = CTRL_REG;              // Switch to instruction register
// Set LCD_DATA to high nibble of Clear Screen
LCD_DATA = (LCD_DATA&0x0F)|0x00;
LCD_E = 1; LCD_E = 0;           // Write data to display
// Set LCD_DATA to lower nibble of Clear Screen
LCD_DATA = (LCD_DATA&0x0F)|0x10;
LCD_E = 1; LCD_E = 0;           // Write data to display
EA = 1;                         // Enable all interrupts

delay(41);                      // Wait 4.1ms

return;
}


/********************************************************************/
/* Function    : LCD_putchar(value)                             SUB */
/*------------------------------------------------------------------*/
/* Description : Writes the character value to the display          */
/*------------------------------------------------------------------*/
/* Author      : Thorsten Godau  NT8                                */
/*------------------------------------------------------------------*/
/* Input       : unsigned char value    -> character to be written  */
/*------------------------------------------------------------------*/
/* Returnvalue : none                                               */
/*------------------------------------------------------------------*/
/* History     : 06/99    V1.0 Basic routine                        */
/*                                                                  */
/********************************************************************/
void LCD_putchar(unsigned char value)
{

EA = 0;                         // Disable all interrupts
LCD_RS = DATA_REG;              // Switch to data register
// Set LCD_DATA to high nibble of value
LCD_DATA = (LCD_DATA&0x0F)|(value&0xF0);
LCD_E = 1; LCD_E = 0;           // Write data to display
// Set LCD_DATA to lower nibble of value
LCD_DATA = (LCD_DATA&0x0F)|((value<<4)&0xF0);
LCD_E = 1; LCD_E = 0;           // Write data to display
EA = 1;                         // Enable all interrupts

delay(4);                       // Wait 400祍

return;
}


/********************************************************************/
/* Function    : LCD_printxy(x,y,*text)                         SUB */
/*------------------------------------------------------------------*/
/* Description : Prints text to position x/y of the display         */
/*------------------------------------------------------------------*/
/* Author      : Thorsten Godau  NT8                                */
/*------------------------------------------------------------------*/
/* Input       : unsigned char x     -> x position of the display   */
/*               unsigned char y     -> y position of the display   */
/*               unsigned char *text -> pointer to text             */
/*------------------------------------------------------------------*/
/* Returnvalue : none                                               */
/*------------------------------------------------------------------*/
/* History     : 06/99    V1.0 Basic routine                        */
/*                                                                  */
/********************************************************************/
void LCD_printxy(unsigned char x,unsigned char y, unsigned char *text)
{

gotoxy(x,y);            // Set cursor position

while( *text )          // while not end of text
  {
  LCD_putchar(*text++); // Write character and increment position
  } 

return;
}


/********************************************************************/
/* Function    : delay(delaytime)                               SUB */
/*------------------------------------------------------------------*/
/* Description : Routine waits (dependening on Timer 0) for about   */
/*               delaytime * 100祍. Best for delaytime > 10         */
/*------------------------------------------------------------------*/
/* Author      : Thorsten Godau  NT8                                */
/*------------------------------------------------------------------*/
/* Input       : unsigned int time_100祍                            */
/*------------------------------------------------------------------*/
/* Returnvalue : none                                               */
/*------------------------------------------------------------------*/
/* History     : 06/99    V1.0 Basic routine                        */
/*               09/99    V1.1 nop inserted in delay-loop           */
/*                                                                  */
/********************************************************************/
void delay(unsigned int time_100us)
{

if ( time_100us == 0 ) return;   // Return if no delaytime is assigned

DELAY = time_100us;              // Set global delaytime
   
while ( DELAY > 0 )
  {
  _asm
    nop
  _endasm;
  }             // Wait delaytime

return;
}


// MAIN =============================================================
void main( void )
{
init_MCU();                                            // Initialize MCU
init_LCD();                                            // Initialize the LCD display
                
LCD_printxy(1,1,"Test of the LCD!");                   // Message to LCD
LCD_printxy(1,2,"---4bit mode----");                   // Message to LCD
control_LCD(ON,NOBLINK,HIDE);                          // Display on, cursor hidden and non-blinking

while(1) // Main loop
  {
  // Do nothing
  _asm
    nop
  _endasm;
  }
}
// END MAIN =========================================================