AVRFreaks.net

// My_LCD.c

// Single port 4 BIT LCD control program
// Writen by Carl W. Livingston
// microcarl@roadrunner.com
// AVR Freaks member - microcarl
// December 30, 2006

// **** From the LCD perspective ****
// LCD:RS = PORTx:0
// LCD:R/W = PORTx:1
// LCD:E = PORTx:2
// LCD:Vee = CONTRAST
// LCD:DB0 = GND
// LCD:DB1 = GND
// LCD:DB2 = GND
// LCD:DB3 = GND
// LCD:DB4 <-- 4.7K Ohm <-- PORTx:4
// LCD:DB5 <-- 4.7K Ohm <-- PORTx:5
// LCD:DB6 <-- 4.7K Ohm <-- PORTx:6
// LCD:DB7 <-- 4.7K Ohm <-- PORTx:7

// **** From the I/O PORTx perspective ****
// PORTx:0 = LCD:RS
// PORTx:1 = LCD:R/W
// PORTx:2 = LCD:E
// PORTx:3 = FREE TO USE
// PORTx:4 --> 4.7K Ohm --> LCD:DB4
// PORTx:5 --> 4.7K Ohm --> LCD:DB5
// PORTx:6 --> 4.7K Ohm --> LCD:DB6
// PORTx:7 --> 4.7K Ohm --> LCD:DB7

/*************************************************************/
/*************************************************************/
#include <iom64v.h>

/*************************************************************/
/*************************************************************/
// If you want to define a different LCD control & data port
// do it here!!!
#define LCD_DATA_OUT PORTF
#define LCD_DATA_IN PINF
#define LCD_DDR DDRF
/*************************************************************/
/*************************************************************/
/* Devices tested for compatability
  Tiny2313: PORTB only. 4.7K Ohm Ballast resistors required
  between USCK, MISO and MOSI
  Mega16:   PORTA, PORTB, PORTC, PORTD
  Mega32:   PORTA, PORTB, PORTC, PORTD
  Mega64:   PORTA, PORTB, PORTC, PORTD, PORTE, (((PORTF JTAG disabled)))
  Mega128:   PORTA, PORTB, PORTC, PORTD, PORTE, (((PORTF JTAG disabled)))
  Mega168:   PORTD only 
  Mega644:   PORTA, PORTB, PORTC, PORTD 
*/
 
// Define LCD Register Select as PORTx, 0x01;
#define LCD_RS 0
// Define LCD Read/Write as PORTx, 0x02; 
#define LCD_RW 1
// Define LCD Enable as PORTx, 0x04; 
#define LCD_E 2   

// TURN OFF POWER TO THE DISPLAY
#define PWR_OFF 0x08
// TURN ON POWER TO THE DISPLAY, NO CURSOR
#define   PWR_ON   0x0C
// SET 8 DATA BIT MODE       
#define   DL_CMD   0x30
// SET 4 DATA BITS
#define   DATA_4   0x20
// SET 4 DATA BITS
#define   DATA_8   0x30
// SET 4 DATA BITS, 4 DISPLAY LINES
#define   LINE_4x4   0x28
// SET 8 DATA BITS, 4 DISPLAY LINES
#define   LINE_8x4   0x38
// INCREMENT COMMAND
#define INC_CMD 0x06   
// CLEAR DISPLAY COMMAND       
#define CLR_DSP 0x01

#define LINE1 0x80
#define LINE2 0xC0
#define LINE3 0x94
#define LINE4 0xD4

#define NULL 0x00
#define HIGH_MASK 0x0F
#define LOW_MASK 0xF0

const char BANNER_1[] = {"Having Fun"};
const char BANNER_2[] = {"With LCD's"};
const char BANNER_3[] = {"By"};
const char BANNER_4[] = {"Carl W. Livingston"};

void LCD_Delay (unsigned long int d);
void LCD_INIT (void);
void LCD_8_BIT_INIT(char c);
void LCD_PutCmd (char);
void LCD_PutChar (char);
void LCD_PutString (const char *);

void main (void)
{
   LCD_INIT ();
   
   while(1)
   {
       // Add other LCD related program operations here...
   }         
}

void LCD_Delay (unsigned long int d)
{
    unsigned long int n;
    for (n = 0; n < d; n++);
}

void LCD_INIT (void)
{
    // Initialize the AVR controller I/O
    LCD_DDR = 0xFF; // SET LCD_DATA TO ALL PUTPUTS
    LCD_DATA_OUT = 0x01; // SET RS CONTROL LINE TO LOGIC HIGH

   // Initialize the LCD controller
   LCD_DATA_OUT &= ~(1<<LCD_RS);
   LCD_8_BIT_INIT (DATA_8); // SET 8 BIT DATA MODE
   LCD_8_BIT_INIT (DATA_8); // SET 8 BIT DATA MODE
   LCD_8_BIT_INIT (DATA_8); // SET 8 BIT DATA MODE
   LCD_8_BIT_INIT (DATA_4); // SET 4 BIT DATA MODE
   LCD_DATA_OUT |= (1<<LCD_RS);   
   // The display is now in 4 bit data mode
   LCD_PutCmd (LINE_4x4); // SET 4 BIT DATA, 4 DISPLAY LINES
   LCD_PutCmd (CLR_DSP); // Clear the display
   LCD_PutCmd (PWR_ON); // Power up the display

   LCD_PutCmd (LINE1+5);
   LCD_PutString (BANNER_1);
   LCD_PutCmd (LINE2+5);
   LCD_PutString (BANNER_2);
   LCD_PutCmd (LINE3+9);
   LCD_PutString (BANNER_3);
   LCD_PutCmd (LINE4+1);
   LCD_PutString (BANNER_4);   
}

void LCD_8_BIT_INIT(char c)
{
    LCD_DATA_OUT |= (1<<LCD_E);
    LCD_Delay (10); // Wait for the display to respone to the E pulse   
    LCD_DATA_OUT = ((LCD_DATA_IN & HIGH_MASK) | (c & LOW_MASK));
    LCD_Delay (10); // Wait for the display to respone to the E pulse
    LCD_DATA_OUT &= ~(1<<LCD_E);
}
   
void LCD_PutCmd (char c)
{
  LCD_DATA_OUT &= ~(1<<LCD_RS);
  LCD_Delay (200); // Wait for the display to respone to R/S 
  LCD_PutChar(c);
  LCD_Delay (200); // Wait for the display to respone to the data 
  LCD_DATA_OUT |= (1<<LCD_RS);
  LCD_Delay (200); // Wait for the display to respone to R/S   
}

void LCD_PutChar (char c)
{
    // Send the MS Nibble
    LCD_DATA_OUT |= (1<<LCD_E);
    LCD_Delay (10); // Wait for the display to respone to the E pulse   
    LCD_DATA_OUT = ((LCD_DATA_IN & HIGH_MASK) | (c & LOW_MASK));
    LCD_Delay (10); // Wait for the display to respone to the E pulse
    LCD_DATA_OUT &= ~(1<<LCD_E);
   LCD_Delay (10); // Wait for the display to respone to the E pulse
   // Send the LS Nibble
    LCD_DATA_OUT |= (1<<LCD_E);
    LCD_Delay (10); // Wait for the display to respone to the E pulse   
   LCD_DATA_OUT = ((LCD_DATA_IN & HIGH_MASK) | ((c * 16) & LOW_MASK));
    LCD_Delay (10); // Wait for the display to respone to the E pulse
    LCD_DATA_OUT &= ~(1<<LCD_E);
}
 
void LCD_PutString (const char *p)
{
    char n = NULL; // Pointer position counter.
    while (p[n] != NULL) // Keep sending data until the NULL character is found.
         LCD_PutChar(p[n++]);
}