//////////////////////////////////////////////////////////////////////////// //// LCD420.C //// //// Driver for common 4x20 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 1996,1997 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: // B0 enable // B1 rs // B2 rw // B4 D4 // B5 D5 // B6 D6 // B7 D7 // // LCD pins D0-D3 are not used and PIC B3 is not used. 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; #byte lcd = 6 // This puts the entire structure // on to port B (at address 6) #define lcd_type 2 // 0=5x7, 1=5x10, 2=2 lines BYTE const LCD_INIT_STRING[4] = {0x20 | (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 lcdline; BYTE lcd_read_byte() { BYTE low,high; set_tris_b(LCD_READ); lcd.rw = 1; delay_cycles(1); lcd.enable = 1; delay_cycles(1); high = lcd.data; lcd.enable = 0; delay_cycles(1); lcd.enable = 1; delay_us(1); low = lcd.data; lcd.enable = 0; set_tris_b(LCD_WRITE); return( (high<<4) | low); } void lcd_send_nibble( BYTE n ) { lcd.data = 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 >> 4); lcd_send_nibble(n & 0xf); } void lcd_init() { BYTE i; set_tris_b(LCD_WRITE); 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; switch(y) { case 1 : address=0x80;break; case 2 : address=0xc0;break; case 3 : address=0x94;break; case 4 : address=0xd4;break; } address+=x-1; lcd_send_byte(0,address); } void lcd_putc( char c) { switch (c) { case '\f' : lcd_send_byte(0,1); lcdline=1; delay_ms(2); break; case '\n' : lcd_gotoxy(1,++lcdline); 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); lcd.rs=1; value = lcd_read_byte(); lcd.rs=0; return(value); }