lcd.c

一个PIC的CCS开发实例

///////////////////////////////////////////////////////////////////////////
////                             LCDD.C                                ////
////                 Driver for common LCD modules                     ////
////                                                                   ////
////  lcd_init()   Must be called before any other function.           ////
////                                                                   ////
////  lcd_putc(c)  Will display c on the next position of the LCD.     ////
////                     The following have special meaning:           ////
////                      \f  Clear display                            ////
////                      \n  Go to start of second line               ////
////                      \b  Move back one position                   ////
////                                                                   ////
////  lcd_gotoxy(x,y) Set write position on LCD (upper left is 1,1)    ////
////                                                                   ////
////  lcd_getc(x,y)   Returns character at position x,y on LCD         ////
////                                                                   ////
///////////////////////////////////////////////////////////////////////////
////        (C) Copyright 1996,2007 Custom Computer Services           ////
//// This source code may only be used by licensed users of the CCS C  ////
//// compiler.  This source code may only be distributed to other      ////
//// licensed users of the CCS C compiler.  No other use, reproduction ////
//// or distribution is permitted without written permission.          ////
//// Derivative programs created using this software in object code    ////
//// form are not restricted in any way.                               ////
///////////////////////////////////////////////////////////////////////////

// As defined in the following structure the pin connection is as follows:
//     D0  enable
//     D1  rs
//     D2  rw
//     D4  D4
//     D5  D5
//     D6  D6
//     D7  D7
//
//   LCD pins D0-D3 are not used and PIC D3 is not used.

// Un-comment the following define to use port B
// #define use_portb_lcd TRUE


struct lcd_pin_map {                 // This structure is overlayed
           BOOLEAN enable;           // on to an I/O port to gain
           BOOLEAN rs;               // access to the LCD pins.
           BOOLEAN rw;               // The bits are allocated from
           BOOLEAN unused;           // low order up.  ENABLE will
           int     data : 4;         // be pin B0.
        } lcd;


#if defined use_portb_lcd
   //#locate lcd = getenv("sfr:PORTB")    // This puts the entire structure over the port
   #ifdef __pch__
    #locate lcd = 0xf81
   #else
    #locate lcd = 6
   #endif
   #define set_tris_lcd(x) set_tris_b(x)
#else
   //#locate lcd = getenv("sfr:PORTD")    // This puts the entire structure over the port
   #ifdef __pch__
    #locate lcd = 0xf82
   #else
    #locate lcd = 7
   #endif
   #define set_tris_lcd(x) set_tris_c(x)
#endif

#ifndef lcd_type
#define lcd_type 2           // 0=5x7, 1=5x10, 2=2 lines
#endif

#define lcd_line_two 0x40    // LCD RAM address for the second line


BYTE const LCD_INIT_STRING[4] = {0x30 | (lcd_type << 2), 0xc, 1, 6};
                             // These bytes need to be sent to the LCD
                             // to start it up.


                             // The following are used for setting
                             // the I/O port direction register.

//struct lcd_pin_map const LCD_WRITE = {0,0,0,0,0}; // For write mode all pins are out
//struct lcd_pin_map const LCD_READ = {0,0,0,0,15}; // For read mode data pins are in



BYTE lcd_read_byte() {
      BYTE data;
      set_tris_d(0xff);
      lcd.rw = 1;
      delay_cycles(1);
      lcd.enable = 1;
      delay_cycles(1);
      data = input_d();
      lcd.enable = 0;
      delay_cycles(1);
      set_tris_d(0xff);
      return data;
}


void lcd_send_nibble( BYTE n ) {
      output_d(n);
      delay_cycles(1);
      lcd.enable = 1;
      delay_us(2);
      lcd.enable = 0;
}


void lcd_send_byte( BYTE address, BYTE n ) {

      lcd.rs = 0;
      while ( bit_test(lcd_read_byte(),7) ) ;
      lcd.rs = address;
      delay_cycles(1);
      lcd.rw = 0;
      delay_cycles(1);
      lcd.enable = 0;
      lcd_send_nibble(n);
}


void lcd_init() {
    BYTE i;
    set_tris_lcd(0x00);
    lcd.rs = 0;
    lcd.rw = 0;
    lcd.enable = 0;
    delay_ms(15);
    for(i=1;i<=3;++i) {
       lcd_send_nibble(3);
       delay_ms(5);
    }
    lcd_send_nibble(2);
    for(i=0;i<=3;++i)
       lcd_send_byte(0,LCD_INIT_STRING[i]);
}


void lcd_gotoxy( BYTE x, BYTE y) {
   BYTE address;

   if(y!=1)
     address=lcd_line_two;
   else
     address=0;
   address+=x-1;
   lcd_send_byte(0,0x80|address);
}

void lcd_putc( char c) {
   switch (c) {
     case '\f'   : lcd_send_byte(0,1);
                   delay_ms(2);
                                           break;
     case '\n'   : lcd_gotoxy(1,2);        break;
     case '\b'   : lcd_send_byte(0,0x10);  break;
     default     : lcd_send_byte(1,c);     break;
   }
}

char lcd_getc( BYTE x, BYTE y) {
   char value;

    lcd_gotoxy(x,y);
    while ( bit_test(lcd_read_byte(),7) ); // wait until busy flag is low
    lcd.rs=1;
    value = lcd_read_byte();
    lcd.rs=0;
    return(value);
}