Read data from EEPROM of Atmega1284 and print it on LCD

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Hi Guys,

This my main code (where I'm trying to just write the data 12 at location 10, and read that back , send it to LCD later): - 

But i'm not sure what is goign wrong LCD just displays "The value read is" an not the actual value :( Can someone point out my mistake

 

 

#ifndef F_CPU

#define F_CPU 16000000UL // clock speed is 16MHz

#endif

#include <stdlib.h>
#include <avr/io.h>
#include <avr/pgmspace.h>
#include <util/delay.h>
#include "lcd.h"
#include <inttypes.h>

int main(void)
{
	 eeprom_write_byte( (uint8_t *) 10 , 12 );
	 eeprom_update_byte( (uint8_t *)10 , 12 );
	 uint8_t StringOfData = eeprom_read_byte( (const uint8_t *)10);
	 lcd_init(LCD_DISP_ON);
	 lcd_puts("The value read is:");
	 lcd_write(StringOfData,1);
}

The other function definitions from Peter Fleury's LCD interfacing code is as follows which I have used in my code above :

 

/*************************************************************************
Title:    Testing output to a HD44780 based LCD display.
Author:   Peter Fleury  <pfleury@gmx.ch>  http://tinyurl.com/peterfleury
File:     $Id: test_lcd.c,v 1.8 2015/01/31 18:04:08 peter Exp $
Software: AVR-GCC 4.x
Hardware: HD44780 compatible LCD text display
          AVR with external SRAM interface if memory-mapped LCD interface is used
          any AVR with 7 free I/O pins if 4-bit IO port mode is used
**************************************************************************/
#include <stdlib.h>
#include <avr/io.h>
#include <avr/pgmspace.h>
#include <util/delay.h>
#include "lcd.h"
#include <inttypes.h>
/*
** constants/macros
*/
#define DDR(x) (*(&x - 1))      /* address of data direction register of port x */
#if defined(__AVR_ATmega64__) || defined(__AVR_ATmega128__)
    /* on ATmega64/128 PINF is on port 0x00 and not 0x60 */
    #define PIN(x) ( &PORTF==&(x) ? _SFR_IO8(0x00) : (*(&x - 2)) )
#else
	#define PIN(x) (*(&x - 2))    /* address of input register of port x          */
#endif

#if LCD_IO_MODE
#define lcd_e_delay()   _delay_us(LCD_DELAY_ENABLE_PULSE)
#define lcd_e_high()    LCD_E_PORT  |=  _BV(LCD_E_PIN);
#define lcd_e_low()     LCD_E_PORT  &= ~_BV(LCD_E_PIN);
#define lcd_e_toggle()  toggle_e()
#define lcd_rw_high()   LCD_RW_PORT |=  _BV(LCD_RW_PIN)
#define lcd_rw_low()    LCD_RW_PORT &= ~_BV(LCD_RW_PIN)
#define lcd_rs_high()   LCD_RS_PORT |=  _BV(LCD_RS_PIN)
#define lcd_rs_low()    LCD_RS_PORT &= ~_BV(LCD_RS_PIN)
#endif

#if LCD_IO_MODE
#if LCD_LINES==1
#define LCD_FUNCTION_DEFAULT    LCD_FUNCTION_4BIT_1LINE
#else
#define LCD_FUNCTION_DEFAULT    LCD_FUNCTION_4BIT_2LINES
#endif
#else
#if LCD_LINES==1
#define LCD_FUNCTION_DEFAULT    LCD_FUNCTION_8BIT_1LINE
#else
#define LCD_FUNCTION_DEFAULT    LCD_FUNCTION_8BIT_2LINES
#endif
#endif

#if LCD_CONTROLLER_KS0073
#if LCD_LINES==4

#define KS0073_EXTENDED_FUNCTION_REGISTER_ON  0x2C   /* |0|010|1100 4-bit mode, extension-bit RE = 1 */
#define KS0073_EXTENDED_FUNCTION_REGISTER_OFF 0x28   /* |0|010|1000 4-bit mode, extension-bit RE = 0 */
#define KS0073_4LINES_MODE                    0x09   /* |0|000|1001 4 lines mode */

#endif
#endif

/*
** function prototypes
*/
#if LCD_IO_MODE
static void toggle_e(void);
#endif

/*
** local functions
*/

/*************************************************************************
delay for a minimum of <us> microseconds
the number of loops is calculated at compile-time from MCU clock frequency
*************************************************************************/
#define delay(us)  _delay_us(us) 

#if LCD_IO_MODE
/* toggle Enable Pin to initiate write */
static void toggle_e(void)
{
    lcd_e_high();
    lcd_e_delay();
    lcd_e_low();
}
#endif

/*************************************************************************
Low-level function to write byte to LCD controller
Input:    data   byte to write to LCD
          rs     1: write data
                 0: write instruction
Returns:  none
*************************************************************************/
#if LCD_IO_MODE
static void lcd_write(uint8_t data,uint8_t rs)
{
    unsigned char dataBits ;

    if (rs) {        /* write data        (RS=1, RW=0) */
       lcd_rs_high();
    } else {         /* write instruction (RS=0, RW=0) */
       lcd_rs_low();
    }
    lcd_rw_low();    /* RW=0  write mode      */

    if ( ( &LCD_DATA0_PORT == &LCD_DATA1_PORT) && ( &LCD_DATA1_PORT == &LCD_DATA2_PORT ) && ( &LCD_DATA2_PORT == &LCD_DATA3_PORT )
      && (LCD_DATA0_PIN == 0) && (LCD_DATA1_PIN == 1) && (LCD_DATA2_PIN == 2) && (LCD_DATA3_PIN == 3) )
    {
        /* configure data pins as output */
        DDR(LCD_DATA0_PORT) |= 0x0F;

        /* output high nibble first */
        dataBits = LCD_DATA0_PORT & 0xF0;
        LCD_DATA0_PORT = dataBits |((data>>4)&0x0F);
        lcd_e_toggle();

        /* output low nibble */
        LCD_DATA0_PORT = dataBits | (data&0x0F);
        lcd_e_toggle();

        /* all data pins high (inactive) */
        LCD_DATA0_PORT = dataBits | 0x0F;
    }
    else
    {
        /* configure data pins as output */
        DDR(LCD_DATA0_PORT) |= _BV(LCD_DATA0_PIN);
        DDR(LCD_DATA1_PORT) |= _BV(LCD_DATA1_PIN);
        DDR(LCD_DATA2_PORT) |= _BV(LCD_DATA2_PIN);
        DDR(LCD_DATA3_PORT) |= _BV(LCD_DATA3_PIN);

        /* output high nibble first */
        LCD_DATA3_PORT &= ~_BV(LCD_DATA3_PIN);
        LCD_DATA2_PORT &= ~_BV(LCD_DATA2_PIN);
        LCD_DATA1_PORT &= ~_BV(LCD_DATA1_PIN);
        LCD_DATA0_PORT &= ~_BV(LCD_DATA0_PIN);
    	if(data & 0x80) LCD_DATA3_PORT |= _BV(LCD_DATA3_PIN);
    	if(data & 0x40) LCD_DATA2_PORT |= _BV(LCD_DATA2_PIN);
    	if(data & 0x20) LCD_DATA1_PORT |= _BV(LCD_DATA1_PIN);
    	if(data & 0x10) LCD_DATA0_PORT |= _BV(LCD_DATA0_PIN);
        lcd_e_toggle();

        /* output low nibble */
        LCD_DATA3_PORT &= ~_BV(LCD_DATA3_PIN);
        LCD_DATA2_PORT &= ~_BV(LCD_DATA2_PIN);
        LCD_DATA1_PORT &= ~_BV(LCD_DATA1_PIN);
        LCD_DATA0_PORT &= ~_BV(LCD_DATA0_PIN);
    	if(data & 0x08) LCD_DATA3_PORT |= _BV(LCD_DATA3_PIN);
    	if(data & 0x04) LCD_DATA2_PORT |= _BV(LCD_DATA2_PIN);
    	if(data & 0x02) LCD_DATA1_PORT |= _BV(LCD_DATA1_PIN);
    	if(data & 0x01) LCD_DATA0_PORT |= _BV(LCD_DATA0_PIN);
        lcd_e_toggle();        

        /* all data pins high (inactive) */
        LCD_DATA0_PORT |= _BV(LCD_DATA0_PIN);
        LCD_DATA1_PORT |= _BV(LCD_DATA1_PIN);
        LCD_DATA2_PORT |= _BV(LCD_DATA2_PIN);
        LCD_DATA3_PORT |= _BV(LCD_DATA3_PIN);
    }
}
#else
#define lcd_write(d,rs) if (rs) *(volatile uint8_t*)(LCD_IO_DATA) = d; else *(volatile uint8_t*)(LCD_IO_FUNCTION) = d;
/* rs==0 -> write instruction to LCD_IO_FUNCTION */
/* rs==1 -> write data to LCD_IO_DATA */
#endif

/*************************************************************************
Low-level function to read byte from LCD controller
Input:    rs     1: read data
                 0: read busy flag / address counter
Returns:  byte read from LCD controller
*************************************************************************/
#if LCD_IO_MODE
static uint8_t lcd_read(uint8_t rs)
{
    uint8_t data;

    if (rs)
        lcd_rs_high();                       /* RS=1: read data      */
    else
        lcd_rs_low();                        /* RS=0: read busy flag */
    lcd_rw_high();                           /* RW=1  read mode      */

    if ( ( &LCD_DATA0_PORT == &LCD_DATA1_PORT) && ( &LCD_DATA1_PORT == &LCD_DATA2_PORT ) && ( &LCD_DATA2_PORT == &LCD_DATA3_PORT )
      && ( LCD_DATA0_PIN == 0 )&& (LCD_DATA1_PIN == 1) && (LCD_DATA2_PIN == 2) && (LCD_DATA3_PIN == 3) )
    {
        DDR(LCD_DATA0_PORT) &= 0xF0;         /* configure data pins as input */

        lcd_e_high();
        lcd_e_delay();
        data = PIN(LCD_DATA0_PORT) << 4;     /* read high nibble first */
        lcd_e_low();

        lcd_e_delay();                       /* Enable 500ns low       */

        lcd_e_high();
        lcd_e_delay();
        data |= PIN(LCD_DATA0_PORT)&0x0F;    /* read low nibble        */
        lcd_e_low();
    }
    else
    {
        /* configure data pins as input */
        DDR(LCD_DATA0_PORT) &= ~_BV(LCD_DATA0_PIN);
        DDR(LCD_DATA1_PORT) &= ~_BV(LCD_DATA1_PIN);
        DDR(LCD_DATA2_PORT) &= ~_BV(LCD_DATA2_PIN);
        DDR(LCD_DATA3_PORT) &= ~_BV(LCD_DATA3_PIN);

        /* read high nibble first */
        lcd_e_high();
        lcd_e_delay();
        data = 0;
        if ( PIN(LCD_DATA0_PORT) & _BV(LCD_DATA0_PIN) ) data |= 0x10;
        if ( PIN(LCD_DATA1_PORT) & _BV(LCD_DATA1_PIN) ) data |= 0x20;
        if ( PIN(LCD_DATA2_PORT) & _BV(LCD_DATA2_PIN) ) data |= 0x40;
        if ( PIN(LCD_DATA3_PORT) & _BV(LCD_DATA3_PIN) ) data |= 0x80;
        lcd_e_low();

        lcd_e_delay();                       /* Enable 500ns low       */

        /* read low nibble */
        lcd_e_high();
        lcd_e_delay();
        if ( PIN(LCD_DATA0_PORT) & _BV(LCD_DATA0_PIN) ) data |= 0x01;
        if ( PIN(LCD_DATA1_PORT) & _BV(LCD_DATA1_PIN) ) data |= 0x02;
        if ( PIN(LCD_DATA2_PORT) & _BV(LCD_DATA2_PIN) ) data |= 0x04;
        if ( PIN(LCD_DATA3_PORT) & _BV(LCD_DATA3_PIN) ) data |= 0x08;
        lcd_e_low();
    }
    return data;
}
#else
#define lcd_read(rs) (rs) ? *(volatile uint8_t*)(LCD_IO_DATA+LCD_IO_READ) : *(volatile uint8_t*)(LCD_IO_FUNCTION+LCD_IO_READ)
/* rs==0 -> read instruction from LCD_IO_FUNCTION */
/* rs==1 -> read data from LCD_IO_DATA */
#endif

/*************************************************************************
loops while lcd is busy, returns address counter
*************************************************************************/
static uint8_t lcd_waitbusy(void)

{
    register uint8_t c;

    /* wait until busy flag is cleared */
    while ( (c=lcd_read(0)) & (1<<LCD_BUSY)) {}

    /* the address counter is updated 4us after the busy flag is cleared */
    delay(LCD_DELAY_BUSY_FLAG);

    /* now read the address counter */
    return (lcd_read(0));  // return address counter

}/* lcd_waitbusy */

/*************************************************************************
Move cursor to the start of next line or to the first line if the cursor
is already on the last line.
*************************************************************************/
static inline void lcd_newline(uint8_t pos)
{
    register uint8_t addressCounter;

#if LCD_LINES==1
    addressCounter = 0;
#endif
#if LCD_LINES==2
    if ( pos < (LCD_START_LINE2) )
        addressCounter = LCD_START_LINE2;
    else
        addressCounter = LCD_START_LINE1;
#endif
#if LCD_LINES==4
#if KS0073_4LINES_MODE
    if ( pos < LCD_START_LINE2 )
        addressCounter = LCD_START_LINE2;
    else if ( (pos >= LCD_START_LINE2) && (pos < LCD_START_LINE3) )
        addressCounter = LCD_START_LINE3;
    else if ( (pos >= LCD_START_LINE3) && (pos < LCD_START_LINE4) )
        addressCounter = LCD_START_LINE4;
    else
        addressCounter = LCD_START_LINE1;
#else
    if ( pos < LCD_START_LINE3 )
        addressCounter = LCD_START_LINE2;
    else if ( (pos >= LCD_START_LINE2) && (pos < LCD_START_LINE4) )
        addressCounter = LCD_START_LINE3;
    else if ( (pos >= LCD_START_LINE3) && (pos < LCD_START_LINE2) )
        addressCounter = LCD_START_LINE4;
    else
        addressCounter = LCD_START_LINE1;
#endif
#endif
    lcd_command((1<<LCD_DDRAM)+addressCounter);

}/* lcd_newline */

/*
** PUBLIC FUNCTIONS
*/

/*************************************************************************
Send LCD controller instruction command
Input:   instruction to send to LCD controller, see HD44780 data sheet
Returns: none
*************************************************************************/
void lcd_command(uint8_t cmd)
{
    lcd_waitbusy();
    lcd_write(cmd,0);
}

/*************************************************************************
Send data byte to LCD controller
Input:   data to send to LCD controller, see HD44780 data sheet
Returns: none
*************************************************************************/
void lcd_data(uint8_t data)
{
    lcd_waitbusy();
    lcd_write(data,1);
}

/*************************************************************************
Set cursor to specified position
Input:    x  horizontal position  (0: left most position)
          y  vertical position    (0: first line)
Returns:  none
*************************************************************************/
void lcd_gotoxy(uint8_t x, uint8_t y)
{
#if LCD_LINES==1
    lcd_command((1<<LCD_DDRAM)+LCD_START_LINE1+x);
#endif
#if LCD_LINES==2
    if ( y==0 )
        lcd_command((1<<LCD_DDRAM)+LCD_START_LINE1+x);
    else
        lcd_command((1<<LCD_DDRAM)+LCD_START_LINE2+x);
#endif
#if LCD_LINES==4
    if ( y==0 )
        lcd_command((1<<LCD_DDRAM)+LCD_START_LINE1+x);
    else if ( y==1)
        lcd_command((1<<LCD_DDRAM)+LCD_START_LINE2+x);
    else if ( y==2)
        lcd_command((1<<LCD_DDRAM)+LCD_START_LINE3+x);
    else /* y==3 */
        lcd_command((1<<LCD_DDRAM)+LCD_START_LINE4+x);
#endif

}/* lcd_gotoxy */

/*************************************************************************
*************************************************************************/
int lcd_getxy(void)
{
    return lcd_waitbusy();
}

/*************************************************************************
Clear display and set cursor to home position
*************************************************************************/
void lcd_clrscr(void)
{
    lcd_command(1<<LCD_CLR);
}

/*************************************************************************
Set cursor to home position
*************************************************************************/
void lcd_home(void)
{
    lcd_command(1<<LCD_HOME);
}

/*************************************************************************
Display character at current cursor position
Input:    character to be displayed
Returns:  none
*************************************************************************/
void lcd_putc(char c)
{
    uint8_t pos;

    pos = lcd_waitbusy();   // read busy-flag and address counter
    if (c=='\n')
    {
        lcd_newline(pos);
    }
    else
    {
#if LCD_WRAP_LINES==1
#if LCD_LINES==1
        if ( pos == LCD_START_LINE1+LCD_DISP_LENGTH ) {
            lcd_write((1<<LCD_DDRAM)+LCD_START_LINE1,0);
        }
#elif LCD_LINES==2
        if ( pos == LCD_START_LINE1+LCD_DISP_LENGTH ) {
            lcd_write((1<<LCD_DDRAM)+LCD_START_LINE2,0);
        }else if ( pos == LCD_START_LINE2+LCD_DISP_LENGTH ){
            lcd_write((1<<LCD_DDRAM)+LCD_START_LINE1,0);
        }
#elif LCD_LINES==4
        if ( pos == LCD_START_LINE1+LCD_DISP_LENGTH ) {
            lcd_write((1<<LCD_DDRAM)+LCD_START_LINE2,0);
        }else if ( pos == LCD_START_LINE2+LCD_DISP_LENGTH ) {
            lcd_write((1<<LCD_DDRAM)+LCD_START_LINE3,0);
        }else if ( pos == LCD_START_LINE3+LCD_DISP_LENGTH ) {
            lcd_write((1<<LCD_DDRAM)+LCD_START_LINE4,0);
        }else if ( pos == LCD_START_LINE4+LCD_DISP_LENGTH ) {
            lcd_write((1<<LCD_DDRAM)+LCD_START_LINE1,0);
        }
#endif
        lcd_waitbusy();
#endif
        lcd_write(c, 1);
    }

}/* lcd_putc */

/*************************************************************************
Display string without auto linefeed
Input:    string to be displayed
Returns:  none
*************************************************************************/
void lcd_puts(const char *s)
/* print string on lcd (no auto linefeed) */
{
    register char c;

    while ( (c = *s++) ) {
        lcd_putc(c);
    }

}/* lcd_puts */

/*************************************************************************
Display string from program memory without auto linefeed
Input:     string from program memory be be displayed
Returns:   none
*************************************************************************/
void lcd_puts_p(const char *progmem_s)
/* print string from program memory on lcd (no auto linefeed) */
{
    register char c;

    while ( (c = pgm_read_byte(progmem_s++)) ) {
        lcd_putc(c);
    }

}/* lcd_puts_p */

/*************************************************************************
Initialize display and select type of cursor
Input:    dispAttr LCD_DISP_OFF            display off
                   LCD_DISP_ON             display on, cursor off
                   LCD_DISP_ON_CURSOR      display on, cursor on
                   LCD_DISP_CURSOR_BLINK   display on, cursor on flashing
Returns:  none
*************************************************************************/
void lcd_init(uint8_t dispAttr)
{
#if LCD_IO_MODE
    /*
     *  Initialize LCD to 4 bit I/O mode
     */

    if ( ( &LCD_DATA0_PORT == &LCD_DATA1_PORT) && ( &LCD_DATA1_PORT == &LCD_DATA2_PORT ) && ( &LCD_DATA2_PORT == &LCD_DATA3_PORT )
      && ( &LCD_RS_PORT == &LCD_DATA0_PORT) && ( &LCD_RW_PORT == &LCD_DATA0_PORT) && (&LCD_E_PORT == &LCD_DATA0_PORT)
      && (LCD_DATA0_PIN == 0 ) && (LCD_DATA1_PIN == 1) && (LCD_DATA2_PIN == 2) && (LCD_DATA3_PIN == 3)
      && (LCD_RS_PIN == 4 ) && (LCD_RW_PIN == 5) && (LCD_E_PIN == 6 ) )
    {
        /* configure all port bits as output (all LCD lines on same port) */
        DDR(LCD_DATA0_PORT) |= 0x7F;
    }
    else if ( ( &LCD_DATA0_PORT == &LCD_DATA1_PORT) && ( &LCD_DATA1_PORT == &LCD_DATA2_PORT ) && ( &LCD_DATA2_PORT == &LCD_DATA3_PORT )
           && (LCD_DATA0_PIN == 0 ) && (LCD_DATA1_PIN == 1) && (LCD_DATA2_PIN == 2) && (LCD_DATA3_PIN == 3) )
    {
        /* configure all port bits as output (all LCD data lines on same port, but control lines on different ports) */
        DDR(LCD_DATA0_PORT) |= 0x0F;
        DDR(LCD_RS_PORT)    |= _BV(LCD_RS_PIN);
        DDR(LCD_RW_PORT)    |= _BV(LCD_RW_PIN);
        DDR(LCD_E_PORT)     |= _BV(LCD_E_PIN);
    }
    else
    {
        /* configure all port bits as output (LCD data and control lines on different ports */
        DDR(LCD_RS_PORT)    |= _BV(LCD_RS_PIN);
        DDR(LCD_RW_PORT)    |= _BV(LCD_RW_PIN);
        DDR(LCD_E_PORT)     |= _BV(LCD_E_PIN);
        DDR(LCD_DATA0_PORT) |= _BV(LCD_DATA0_PIN);
        DDR(LCD_DATA1_PORT) |= _BV(LCD_DATA1_PIN);
        DDR(LCD_DATA2_PORT) |= _BV(LCD_DATA2_PIN);
        DDR(LCD_DATA3_PORT) |= _BV(LCD_DATA3_PIN);
    }
    delay(LCD_DELAY_BOOTUP);             /* wait 16ms or more after power-on       */

    /* initial write to lcd is 8bit */
    LCD_DATA1_PORT |= _BV(LCD_DATA1_PIN);    // LCD_FUNCTION>>4;
    LCD_DATA0_PORT |= _BV(LCD_DATA0_PIN);    // LCD_FUNCTION_8BIT>>4;
    lcd_e_toggle();
    delay(LCD_DELAY_INIT);               /* delay, busy flag can't be checked here */

    /* repeat last command */
    lcd_e_toggle();
    delay(LCD_DELAY_INIT_REP);           /* delay, busy flag can't be checked here */

    /* repeat last command a third time */
    lcd_e_toggle();
    delay(LCD_DELAY_INIT_REP);           /* delay, busy flag can't be checked here */

    /* now configure for 4bit mode */
    LCD_DATA0_PORT &= ~_BV(LCD_DATA0_PIN);   // LCD_FUNCTION_4BIT_1LINE>>4
    lcd_e_toggle();
    delay(LCD_DELAY_INIT_4BIT);          /* some displays need this additional delay */

    /* from now the LCD only accepts 4 bit I/O, we can use lcd_command() */
#else
    /*
     * Initialize LCD to 8 bit memory mapped mode
     */

    /* enable external SRAM (memory mapped lcd) and one wait state */
    MCUCR = _BV(SRE) | _BV(SRW);

    /* reset LCD */
    delay(LCD_DELAY_BOOTUP);                    /* wait 16ms after power-on     */
    lcd_write(LCD_FUNCTION_8BIT_1LINE,0);   /* function set: 8bit interface */
    delay(LCD_DELAY_INIT);                      /* wait 5ms                     */
    lcd_write(LCD_FUNCTION_8BIT_1LINE,0);   /* function set: 8bit interface */
    delay(LCD_DELAY_INIT_REP);                  /* wait 64us                    */
    lcd_write(LCD_FUNCTION_8BIT_1LINE,0);   /* function set: 8bit interface */
    delay(LCD_DELAY_INIT_REP);                  /* wait 64us                    */
#endif

#if KS0073_4LINES_MODE
    /* Display with KS0073 controller requires special commands for enabling 4 line mode */
	lcd_command(KS0073_EXTENDED_FUNCTION_REGISTER_ON);
	lcd_command(KS0073_4LINES_MODE);
	lcd_command(KS0073_EXTENDED_FUNCTION_REGISTER_OFF);
#else
    lcd_command(LCD_FUNCTION_DEFAULT);      /* function set: display lines  */
#endif
    lcd_command(LCD_DISP_OFF);              /* display off                  */
    lcd_clrscr();                           /* display clear                */
    lcd_command(LCD_MODE_DEFAULT);          /* set entry mode               */
    lcd_command(dispAttr);                  /* display/cursor control       */

}/* lcd_init */

/*
** constant definitions
*/
static const PROGMEM unsigned char copyRightChar[] =
{
	0x07, 0x08, 0x13, 0x14, 0x14, 0x13, 0x08, 0x07,
	0x00, 0x10, 0x08, 0x08, 0x08, 0x08, 0x10, 0x00
};

/*
** function prototypes
*/
void wait_until_key_pressed(void);

void wait_until_key_pressed(void)
{
    unsigned char temp1, temp2;

    do {
        temp1 = PIND;                  // read input
        _delay_ms(5);                  // delay for key debounce
        temp2 = PIND;                  // read input
        temp1 = (temp1 & temp2);       // debounce input
    } while ( temp1 & _BV(PIND2) );

    loop_until_bit_is_set(PIND,PIND2);            /* wait until key is released */
}

int main(void)
{
    char buffer[7];
    int  num=134;
    unsigned char i;

    DDRD &=~ (1 << PD2);        /* Pin PD2 input              */
    PORTD |= (1 << PD2);        /* Pin PD2 pull-up enabled    */

    /* initialize display, cursor off */
    lcd_init(LCD_DISP_ON);

    for (;;) {                           /* loop forever */
        /*
         * Test 1:  write text to display
         */

        /* clear display and home cursor */
        lcd_clrscr();

        /* put string to display (line 1) with linefeed */
        lcd_puts("LCD Test Line 1\n");

        /* cursor is now on second line, write second line */
        lcd_puts("Line 2");

        /* move cursor to position 8 on line 2 */
        lcd_gotoxy(7,1);  

        /* write single char to display */
        lcd_putc(':');

        /* wait until push button PD2 (INT0) is pressed */
        wait_until_key_pressed();

        /*
         * Test 2: use lcd_command() to turn on cursor
         */

        /* turn on cursor */
        lcd_command(LCD_DISP_ON_CURSOR);

        /* put string */
        lcd_puts( "CurOn");

        /* wait until push button PD2 (INT0) is pressed */
        wait_until_key_pressed();

        /*
         * Test 3: display shift
         */

        lcd_clrscr();     /* clear display home cursor */

        /* put string from program memory to display */
        lcd_puts_P( "Line 1 longer than 14 characters\n" );
        lcd_puts_P( "Line 2 longer than 14 characters" );

        /* move BOTH lines one position to the left */
        lcd_command(LCD_MOVE_DISP_LEFT);

        /* wait until push button PD2 (INT0) is pressed */
        wait_until_key_pressed();

        /* turn off cursor */
        lcd_command(LCD_DISP_ON);

        /*
         *   Test: Display integer values
         */

        lcd_clrscr();   /* clear display home cursor */

        /* convert interger into string */
        itoa( num , buffer, 10);

        /* put converted string to display */
        lcd_puts(buffer);

        /* wait until push button PD2 (INT0) is pressed */
        wait_until_key_pressed();

        /*
         *  Test: Display userdefined characters
         */

       lcd_clrscr();   /* clear display home cursor */

       lcd_puts("Copyright: ");

       /*
        * load two userdefined characters from program memory
        * into LCD controller CG RAM location 0 and 1
        */
       lcd_command(_BV(LCD_CGRAM));  /* set CG RAM start address 0 */
       for(i=0; i<16; i++)
       {
           lcd_data(pgm_read_byte_near(&copyRightChar[i]));
       }

       /* move cursor to position 0 on line 2 */
       /* Note: this switched back to DD RAM adresses */
       lcd_gotoxy(0,1);

       /* display user defined (c), built using two user defined chars */
       lcd_putc(0);
       lcd_putc(1);

       /* wait until push button PD2 (INT0) is pressed */
       wait_until_key_pressed();

    }
}

And the header file lcd.h is as follows :

 

#ifndef LCD_H
#define LCD_H
/*************************************************************************
 Title	:   C include file for the HD44780U LCD library (lcd.c)
 Author:    Peter Fleury <pfleury@gmx.ch>  http://tinyurl.com/peterfleury
 File:	    $Id: lcd.h,v 1.14.2.4 2015/01/20 17:16:07 peter Exp $
 Software:  AVR-GCC 4.x
 Hardware:  any AVR device, memory mapped mode only for AVR with
            memory mapped interface (AT90S8515/ATmega8515/ATmega128)
***************************************************************************/

/**
 @mainpage
 Collection of libraries for AVR-GCC
 @author Peter Fleury pfleury@gmx.ch http://tinyurl.com/peterfleury
 @copyright (C) 2015 Peter Fleury, GNU General Public License Version 3

 @file
 @defgroup pfleury_lcd LCD library <lcd.h>
 @code #include <lcd.h> @endcode

 @brief Basic routines for interfacing a HD44780U-based character LCD display

 LCD character displays can be found in many devices, like espresso machines, laser printers.
 The Hitachi HD44780 controller and its compatible controllers like Samsung KS0066U have become an industry standard for these types of displays. 

 This library allows easy interfacing with a HD44780 compatible display and can be
 operated in memory mapped mode (LCD_IO_MODE defined as 0 in the include file lcd.h.) or in
 4-bit IO port mode (LCD_IO_MODE defined as 1). 8-bit IO port mode is not supported.

 Memory mapped mode is compatible with old Kanda STK200 starter kit, but also supports
 generation of R/W signal through A8 address line.

 @see The chapter <a href=" http://homepage.hispeed.ch/peterfleury/avr-lcd44780.html" target="_blank">Interfacing a HD44780 Based LCD to an AVR</a>
      on my home page, which shows example circuits how to connect an LCD to an AVR controller. 

 @author Peter Fleury pfleury@gmx.ch http://tinyurl.com/peterfleury

 @version   2.0

 @copyright (C) 2015 Peter Fleury, GNU General Public License Version 3

*/

#include <inttypes.h>
#include <avr/pgmspace.h>

#if (__GNUC__ * 100 + __GNUC_MINOR__) < 405
#error "This library requires AVR-GCC 4.5 or later, update to newer AVR-GCC compiler !"
#endif

/**@{*/

/*
 * LCD and target specific definitions below can be defined in a separate include file with name lcd_definitions.h instead modifying this file
 * by adding -D_LCD_DEFINITIONS_FILE to the CDEFS section in the Makefile
 * All definitions added to the file lcd_definitions.h will override the default definitions from lcd.h
 */
#ifdef _LCD_DEFINITIONS_FILE
#include "lcd_definitions.h"
#endif

/**
 * @name  Definition for LCD controller type
 * Use 0 for HD44780 controller, change to 1 for displays with KS0073 controller.
 */
#ifndef LCD_CONTROLLER_KS0073
#define LCD_CONTROLLER_KS0073 0  /**< Use 0 for HD44780 controller, 1 for KS0073 controller */
#endif

/**
 * @name  Definitions for Display Size
 * Change these definitions to adapt setting to your display
 *
 * These definitions can be defined in a separate include file \b lcd_definitions.h instead modifying this file by
 * adding -D_LCD_DEFINITIONS_FILE to the CDEFS section in the Makefile.
 * All definitions added to the file lcd_definitions.h will override the default definitions from lcd.h
 *
 */
#ifndef LCD_LINES
#define LCD_LINES           2     /**< number of visible lines of the display */
#endif
#ifndef LCD_DISP_LENGTH
#define LCD_DISP_LENGTH    16     /**< visibles characters per line of the display */
#endif
#ifndef LCD_LINE_LENGTH
#define LCD_LINE_LENGTH  0x40     /**< internal line length of the display    */
#endif
#ifndef LCD_START_LINE1
#define LCD_START_LINE1  0x00     /**< DDRAM address of first char of line 1 */
#endif
#ifndef LCD_START_LINE2
#define LCD_START_LINE2  0x40     /**< DDRAM address of first char of line 2 */
#endif
#ifndef LCD_START_LINE3
#define LCD_START_LINE3  0x14     /**< DDRAM address of first char of line 3 */
#endif
#ifndef LCD_START_LINE4
#define LCD_START_LINE4  0x54     /**< DDRAM address of first char of line 4 */
#endif
#ifndef LCD_WRAP_LINES
#define LCD_WRAP_LINES      0     /**< 0: no wrap, 1: wrap at end of visibile line */
#endif

/**
 * @name Definitions for 4-bit IO mode
 *
 * The four LCD data lines and the three control lines RS, RW, E can be on the
 * same port or on different ports.
 * Change LCD_RS_PORT, LCD_RW_PORT, LCD_E_PORT if you want the control lines on
 * different ports.
 *
 * Normally the four data lines should be mapped to bit 0..3 on one port, but it
 * is possible to connect these data lines in different order or even on different
 * ports by adapting the LCD_DATAx_PORT and LCD_DATAx_PIN definitions.
 *
 * Adjust these definitions to your target.\n
 * These definitions can be defined in a separate include file \b lcd_definitions.h instead modifying this file by
 * adding \b -D_LCD_DEFINITIONS_FILE to the \b CDEFS section in the Makefile.
 * All definitions added to the file lcd_definitions.h will override the default definitions from lcd.h
 *
 */
#define LCD_IO_MODE      1            /**< 0: memory mapped mode, 1: IO port mode */

#if LCD_IO_MODE

#ifndef LCD_PORT
#define LCD_PORT         PORTA        /**< port for the LCD lines   */
#endif
#ifndef LCD_DATA0_PORT
#define LCD_DATA0_PORT   LCD_PORT     /**< port for 4bit data bit 0 */
#endif
#ifndef LCD_DATA1_PORT
#define LCD_DATA1_PORT   LCD_PORT     /**< port for 4bit data bit 1 */
#endif
#ifndef LCD_DATA2_PORT
#define LCD_DATA2_PORT   LCD_PORT     /**< port for 4bit data bit 2 */
#endif
#ifndef LCD_DATA3_PORT
#define LCD_DATA3_PORT   LCD_PORT     /**< port for 4bit data bit 3 */
#endif
#ifndef LCD_DATA0_PIN
#define LCD_DATA0_PIN    0            /**< pin for 4bit data bit 0  */
#endif
#ifndef LCD_DATA1_PIN
#define LCD_DATA1_PIN    1            /**< pin for 4bit data bit 1  */
#endif
#ifndef LCD_DATA2_PIN
#define LCD_DATA2_PIN    2            /**< pin for 4bit data bit 2  */
#endif
#ifndef LCD_DATA3_PIN
#define LCD_DATA3_PIN    3            /**< pin for 4bit data bit 3  */
#endif
#ifndef LCD_RS_PORT
#define LCD_RS_PORT      LCD_PORT     /**< port for RS line         */
#endif
#ifndef LCD_RS_PIN
#define LCD_RS_PIN       4            /**< pin  for RS line         */
#endif
#ifndef LCD_RW_PORT
#define LCD_RW_PORT      LCD_PORT     /**< port for RW line         */
#endif
#ifndef LCD_RW_PIN
#define LCD_RW_PIN       5            /**< pin  for RW line         */
#endif
#ifndef LCD_E_PORT
#define LCD_E_PORT       LCD_PORT     /**< port for Enable line     */
#endif
#ifndef LCD_E_PIN
#define LCD_E_PIN        6            /**< pin  for Enable line     */
#endif

#elif defined(__AVR_AT90S4414__) || defined(__AVR_AT90S8515__) || defined(__AVR_ATmega64__) || \
      defined(__AVR_ATmega8515__)|| defined(__AVR_ATmega103__) || defined(__AVR_ATmega128__) || \
      defined(__AVR_ATmega161__) || defined(__AVR_ATmega162__)
/*
 * memory mapped mode is only supported when the device has an external data memory interface
 */
#define LCD_IO_DATA      0xC000    /* A15=E=1, A14=RS=1                 */
#define LCD_IO_FUNCTION  0x8000    /* A15=E=1, A14=RS=0                 */
#define LCD_IO_READ      0x0100    /* A8 =R/W=1 (R/W: 1=Read, 0=Write   */

#else
#error "external data memory interface not available for this device, use 4-bit IO port mode"

#endif

/**
 * @name Definitions of delays
 * Used to calculate delay timers.
 * Adapt the F_CPU define in the Makefile to the clock frequency in Hz of your target
 *
 * These delay times can be adjusted, if some displays require different delays.\n
 * These definitions can be defined in a separate include file \b lcd_definitions.h instead modifying this file by
 * adding \b -D_LCD_DEFINITIONS_FILE to the \b CDEFS section in the Makefile.
 * All definitions added to the file lcd_definitions.h will override the default definitions from lcd.h
 */
#ifndef LCD_DELAY_BOOTUP
#define LCD_DELAY_BOOTUP   16000      /**< delay in micro seconds after power-on  */
#endif
#ifndef LCD_DELAY_INIT
#define LCD_DELAY_INIT      5000      /**< delay in micro seconds after initialization command sent  */
#endif
#ifndef LCD_DELAY_INIT_REP
#define LCD_DELAY_INIT_REP    64      /**< delay in micro seconds after initialization command repeated */
#endif
#ifndef LCD_DELAY_INIT_4BIT
#define LCD_DELAY_INIT_4BIT   64      /**< delay in micro seconds after setting 4-bit mode */
#endif
#ifndef LCD_DELAY_BUSY_FLAG
#define LCD_DELAY_BUSY_FLAG    4      /**< time in micro seconds the address counter is updated after busy flag is cleared */
#endif
#ifndef LCD_DELAY_ENABLE_PULSE
#define LCD_DELAY_ENABLE_PULSE 1      /**< enable signal pulse width in micro seconds */
#endif

/**
 * @name Definitions for LCD command instructions
 * The constants define the various LCD controller instructions which can be passed to the
 * function lcd_command(), see HD44780 data sheet for a complete description.
 */

/* instruction register bit positions, see HD44780U data sheet */
#define LCD_CLR               0      /* DB0: clear display                  */
#define LCD_HOME              1      /* DB1: return to home position        */
#define LCD_ENTRY_MODE        2      /* DB2: set entry mode                 */
#define LCD_ENTRY_INC         1      /*   DB1: 1=increment, 0=decrement     */
#define LCD_ENTRY_SHIFT       0      /*   DB2: 1=display shift on           */
#define LCD_ON                3      /* DB3: turn lcd/cursor on             */
#define LCD_ON_DISPLAY        2      /*   DB2: turn display on              */
#define LCD_ON_CURSOR         1      /*   DB1: turn cursor on               */
#define LCD_ON_BLINK          0      /*     DB0: blinking cursor ?          */
#define LCD_MOVE              4      /* DB4: move cursor/display            */
#define LCD_MOVE_DISP         3      /*   DB3: move display (0-> cursor) ?  */
#define LCD_MOVE_RIGHT        2      /*   DB2: move right (0-> left) ?      */
#define LCD_FUNCTION          5      /* DB5: function set                   */
#define LCD_FUNCTION_8BIT     4      /*   DB4: set 8BIT mode (0->4BIT mode) */
#define LCD_FUNCTION_2LINES   3      /*   DB3: two lines (0->one line)      */
#define LCD_FUNCTION_10DOTS   2      /*   DB2: 5x10 font (0->5x7 font)      */
#define LCD_CGRAM             6      /* DB6: set CG RAM address             */
#define LCD_DDRAM             7      /* DB7: set DD RAM address             */
#define LCD_BUSY              7      /* DB7: LCD is busy                    */

/* set entry mode: display shift on/off, dec/inc cursor move direction */
#define LCD_ENTRY_DEC            0x04   /* display shift off, dec cursor move dir */
#define LCD_ENTRY_DEC_SHIFT      0x05   /* display shift on,  dec cursor move dir */
#define LCD_ENTRY_INC_           0x06   /* display shift off, inc cursor move dir */
#define LCD_ENTRY_INC_SHIFT      0x07   /* display shift on,  inc cursor move dir */

/* display on/off, cursor on/off, blinking char at cursor position */
#define LCD_DISP_OFF             0x08   /* display off                            */
#define LCD_DISP_ON              0x0C   /* display on, cursor off                 */
#define LCD_DISP_ON_BLINK        0x0D   /* display on, cursor off, blink char     */
#define LCD_DISP_ON_CURSOR       0x0E   /* display on, cursor on                  */
#define LCD_DISP_ON_CURSOR_BLINK 0x0F   /* display on, cursor on, blink char      */

/* move cursor/shift display */
#define LCD_MOVE_CURSOR_LEFT     0x10   /* move cursor left  (decrement)          */
#define LCD_MOVE_CURSOR_RIGHT    0x14   /* move cursor right (increment)          */
#define LCD_MOVE_DISP_LEFT       0x18   /* shift display left                     */
#define LCD_MOVE_DISP_RIGHT      0x1C   /* shift display right                    */

/* function set: set interface data length and number of display lines */
#define LCD_FUNCTION_4BIT_1LINE  0x20   /* 4-bit interface, single line, 5x7 dots */
#define LCD_FUNCTION_4BIT_2LINES 0x28   /* 4-bit interface, dual line,   5x7 dots */
#define LCD_FUNCTION_8BIT_1LINE  0x30   /* 8-bit interface, single line, 5x7 dots */
#define LCD_FUNCTION_8BIT_2LINES 0x38   /* 8-bit interface, dual line,   5x7 dots */

#define LCD_MODE_DEFAULT     ((1<<LCD_ENTRY_MODE) | (1<<LCD_ENTRY_INC) )

/**
 *  @name Functions
 */

/**
 @brief    Initialize display and select type of cursor
 @param    dispAttr \b LCD_DISP_OFF display off\n
                    \b LCD_DISP_ON display on, cursor off\n
                    \b LCD_DISP_ON_CURSOR display on, cursor on\n
                    \b LCD_DISP_ON_CURSOR_BLINK display on, cursor on flashing
 @return  none
*/
extern void lcd_init(uint8_t dispAttr);

/**
 @brief    Clear display and set cursor to home position
 @return   none
*/
extern void lcd_clrscr(void);

/**
 @brief    Set cursor to home position
 @return   none
*/
extern void lcd_home(void);

/**
 @brief    Set cursor to specified position

 @param    x horizontal position\n (0: left most position)
 @param    y vertical position\n   (0: first line)
 @return   none
*/
extern void lcd_gotoxy(uint8_t x, uint8_t y);

/**
 @brief    Display character at current cursor position
 @param    c character to be displayed
 @return   none
*/
extern void lcd_putc(char c);

/**
 @brief    Display string without auto linefeed
 @param    s string to be displayed
 @return   none
*/
extern void lcd_puts(const char *s);

/**
 @brief    Display string from program memory without auto linefeed
 @param    progmem_s string from program memory be be displayed
 @return   none
 @see      lcd_puts_P
*/
extern void lcd_puts_p(const char *progmem_s);

/**
 @brief    Send LCD controller instruction command
 @param    cmd instruction to send to LCD controller, see HD44780 data sheet
 @return   none
*/
extern void lcd_command(uint8_t cmd);

/**
 @brief    Send data byte to LCD controller 

 Similar to lcd_putc(), but without interpreting LF
 @param    data byte to send to LCD controller, see HD44780 data sheet
 @return   none
*/
extern void lcd_data(uint8_t data);

/**
 @brief macros for automatically storing string constant in program memory
*/
#define lcd_puts_P(__s)         lcd_puts_p(PSTR(__s))

/**@}*/

#endif //LCD_H

Thanks a lot for your patience and help. 

This topic has a solution.

TBANRJEE

Last Edited: Thu. Jan 11, 2018 - 08:33 PM
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So the EEPROM is external to the M1284. I recognize that there may be translation issues. Often, when we see "of the Mega1284", many of us will think that you are talking about the native, built-in, EEPROM.

 

Do you have a debugging tool (example: AVR Dragon, and others)? If so, now would be a good time to learn how to use it.

 

There are at least 5 places where this process can fail:

 

1. Not write the VALUE you think you are writing to the EEPROM

2. Not writing to the LOCATION you think you are using within the EEPROM

3. Not reading the same location that you wrote to

4. Incorrectly processing the value that was read from the EEPROM

5. Incorrectly writing to the LCD.

 

So, somehow, you need to identify which of the failures it is. THEN, determine how to correct that failure.

 

Jim

Jim Wagner Oregon Research Electronics, Consulting Div. Tangent, OR, USA http://www.orelectronics.net

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In your previous thread: http://www.avrfreaks.net/forum/16x2-lcd-interfacing-atmega32

 

You said you had the Proteus simulator.

 

One of the key benefits of a simulator is precisely that it lets you step through your code, line-by-line, and see what's happening - so do that!

 

As John says, a debug adaptor lets you do the same thing - but in the real hardware.

 

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Hey actually I started working on these just  a couple of days back. No I do not have a debugging tool :(

Also I just wrote this code on Atmel Studio 7, built it and loaded the hex file on Atmega1284, for simulating on Proteus. So I do not physically have any chip or board or EEPROM with me, I have just been emulating the controller to read and write using Proteus. 

Do you have any other solution that might help me?

 

Thanks a lot though!

TBANRJEE

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Hey @awneil, I'm using Proteus 8 Professional, it will allow me to simulate line by line of my code, really? 

TBANRJEE

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ka7ehk wrote:
So the EEPROM is external to the M1284. I recognize that there may be translation issues. Often, when we see "of the Mega1284", many of us will think that you are talking about the native, built-in, EEPROM.  

I thought the OP was talking about the internal EEPROM.......

 

eeprom_write_byte( (uint8_t *) 10 , 12 );
	 eeprom_update_byte( (uint8_t *)10 , 12 );

Just use the EEPROM UPDATE as you do not need to write to the location AND update it.

 

Also, I do not see the INCLUDE EEPROM.h at the top of your code.  YOu may not need to include it in AS, but I have to in AS6_2.

 

If you are using the internal EEPROM I would suggest reading Deans tutorial on using the EEPROM routines.  I have attached the tutorial to this post

 

 

Attachment(s): 

If you want a career with a known path - become an undertaker. Dead people don't sue! - Kartman

Please Read: Code-of-Conduct

Atmel Studio6.2/AS7, DipTrace, Quartus, MPLAB user

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So you've paid all that cash for the tool, and not bothered to actually find out what it can do?

 

Again, this is not a support or tutorial site for Proteus - you know where to find that ...

 

 

EDIT

 

See the 'Getting Started' tips here: http://www.avrfreaks.net/comment... - for "your debugger" read "your simulator"; ie, Proteus.

 

 

 

 

Last Edited: Thu. Jan 11, 2018 - 08:13 PM
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hello @jgmdesign , 

In my code actually I have all these header files included

#include <avr/io.h>
#include <avr/eeprom.h>
#include <stdlib.h>
#include <avr/pgmspace.h>
#include <util/delay.h>
#include "lcd.h"
#include <inttypes.h>

I just missed it while pasting here somehow. Sorry for that.

 

And yes I also tried just eeprom_update without eeprom_write, but still didnt get any value on display man :(

Tried the other thing as well, just write without update, as the tutorial you have attached says "only if the new value that is to be written

differs from current cell content then update is to be used", However neither of them brought any change to the display on LCD 

Not sure what am I doing wrong as 

 

TBANRJEE

This reply has been marked as the solution. 
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I'm trying to just write the data 12 at location 10, and read that back , send it to LCD later

What do you expect to see when you print 12? And don't tell me 12.....

John Samperi

Ampertronics Pty. Ltd.

www.ampertronics.com.au

* Electronic Design * Custom Products * Contract Assembly

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Tanushree Banerjee wrote:
But i'm not sure what is goign wrong LCD just displays "The value read is" an not the actual value :( Can someone point out my mistake

What value >>do<< you get?  When you look up the character set for your display, what is displayed for 12/0x0c?  [I think it is "nothing"; part of user-defined probably?]

 

Try setting to 0x33, decimal 51, and see if you get a '3'.

 

Image result

ka7ehk wrote:
So the EEPROM is external to the M1284.

???  What makes you think that? 

You can put lipstick on a pig, but it is still a pig.

I've never met a pig I didn't like, as long as you have some salt and pepper.

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Thank you so much Sir! The ASCII character values are what i'm seeing! Dunno how I overlooked this fact

TBANRJEE

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Yeah I understood my mistake! Thank you so much for pointing it  out!

TBANRJEE

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It looks like you slapped some libraries together, scratch you head why it doesn't work immediately and then want "us" to figure that out for you ???

It's your code. You have controll over it and can debug / simulate it.

Chop your problems into little pieces you can examine one at a time.

 

I also do not like this construction:

#ifndef F_CPU
#define F_CPU 12345
#endif

Compare with this:

#ifndef F_CPU
#warning "F_CPU should have been defined here."
// But this is silly code. If you try to use F_CPU without defining it you'll get an error anyway.
// Use the tool of the compiler in a smart way.
#endif 

Or even the more simple looking:

#define F_CPU   12345       // Will generate redefinion error if already defined.

The main goal is to be absolutely certain that all code which depends on F_CPU uses the same definiton.

The easiest way to be sure of this is to have only one definition of F_CPU.

It is often defined in a makefile and then included from there in each source code file during compilation

Paul van der Hoeven.
Bunch of old projects with AVR's:
http://www.hoevendesign.com

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Paulvdh wrote:
It looks like you slapped some libraries together, scratch you head why it doesn't work immediately and then want "us" to figure that out for you ???

Indeed.

 

Chop your problems into little pieces you can examine one at a time.

Actually, you should have done that before you even started writing any code at all.

 

You need to design first - then code what you have designed.

 

Your design should break the Big Problem down into its component parts.

 

When you start coding, you should then code one part at a time and thoroughly test it before moving on to the next.

 

Just writing one huge, monolithic blob of code and hoping that it will all "just work" is doomed to failure - as you have seen!

 

 

 

I also do not like this construction:

#ifndef F_CPU
#define F_CPU 12345
#endif

Likewise

 

Compare with this:

#ifndef F_CPU
#warning "F_CPU should have been defined here."
// But this is silly code. If you try to use F_CPU without defining it you'll get an error anyway.
// Use the tool of the compiler in a smart way.
#endif

 

Or, IMO, better yet:

#ifndef F_CPU
#error "F_CPU must be defined as the CPU clock frequency, in Hz."
#endif

It has a number of advantages; eg,

  • it's better than a warning - as warnings can be (and all too often are) ignored.
  • it's better than just a compiler "undefined identifier" as it tells you exactly what to do to fix the error
    (further explanatory comments could be added).
  • #warning is non-standard; #error isn't.

 

 

The main goal is to be absolutely certain that all code which depends on F_CPU uses the same definiton.

It also needs to be the correct value!

 

The easiest way to be sure of this is to have only one definition of F_CPU.

Indeed.

 

It is often defined in a makefile

or in the IDE Project settings.