LCD ohne Lib

Hallo,
ich versuche ein LCD ein LCd anzusteuern, ohne eine Lib zu verwenden.
Mit Lib funktionierts, mit meinem Versuch nicht :(

#include <inttypes.h>
#include <avr/io.h>
#include <util/delay.h>

#define LCD_RS_PORT PORTB
#define LCD_RS_PIN 3
#define LCD_DATA0_PORT   PORTD     /**< port for 4bit data bit 0 */
#define LCD_DATA1_PORT   PORTD     /**< port for 4bit data bit 1 */
#define LCD_DATA2_PORT   PORTD     /**< port for 4bit data bit 2 */
#define LCD_DATA3_PORT   PORTB     /**< port for 4bit data bit 3 */
#define LCD_DATA0_PIN    5            /**< pin for 4bit data bit 0  */
#define LCD_DATA1_PIN    6           /**< pin for 4bit data bit 1  */
#define LCD_DATA2_PIN    7            /**< pin for 4bit data bit 2  */
#define LCD_DATA3_PIN    0
#define LCD_RW_PORT      PORTB     /**< port for RW line         */
#define LCD_RW_PIN       4            /**< pin  for RW line         */
#define LCD_E_PORT       PORTB     /**< port for Enable line     */
#define LCD_E_PIN        2            /**< pin  for Enable line     */
#define LCD_E_PORT       PORTB     /**< port for Enable line     */
#define LCD_E_PIN        1            /**< pin  for Enable line     */



void write_data(uint8_t wert)
{
 if(wert & (1<<0))
  {
   LCD_DATA0_PORT &=  ~(1 << LCD_DATA0_PIN);
  }
 else
  {
   LCD_DATA0_PORT |=  (1 << LCD_DATA0_PIN);
  }

 if(wert & (1<<1))
  {
   LCD_DATA1_PORT &=  ~(1 << LCD_DATA1_PIN);
  }
 else
  {
   LCD_DATA1_PORT |=  (1 << LCD_DATA1_PIN);
  }

 if(wert & (1<<2))
  {
   LCD_DATA2_PORT &=  ~(1 << LCD_DATA2_PIN);
  }
 else
  {
   LCD_DATA2_PORT |=  (1 << LCD_DATA2_PIN);
  }
 if(wert & (1<<3))
  {
   LCD_DATA3_PORT &=  ~(1 << LCD_DATA3_PIN);
  }
 else
  {
   LCD_DATA3_PORT |=  (1 << LCD_DATA3_PIN);
  }

}

void lcd_enable(void)
{
 LCD_E_PORT |= (1<<LCD_E_PIN);
 __asm volatile ("nop");
 __asm volatile ("nop");
 __asm volatile ("nop");
 __asm volatile ("nop");
 __asm volatile ("nop");
LCD_E_PORT &= ~(1<<LCD_E_PIN);
}

void init_lcd(void)
{
 _delay_ms(20);

 LCD_RS_PORT &= ~(1<<LCD_RS_PIN);  /* Steuerregister wird angesprochen
*/
 write_data(0x3);                  /* 1.0x3 */
 lcd_enable;

 _delay_ms(8);
 write_data(0x3);                    /* 2.0x3 */
 lcd_enable;

 _delay_ms(1);
 write_data(0x3);                      /* 3.0x3 */
 lcd_enable;
 _delay_ms(5);

 write_data(0x2);                     /* Explizit 4-Bit einstellen */
 lcd_enable;
 _delay_ms(5);
 write_data(0x0);
 lcd_enable;
 _delay_ms(5);
                                     /*Nochmal System-Set 4bit...*/
 write_data(0x2);
 lcd_enable;
 _delay_ms(5);
 write_data(0x8);                  /* Anderes von System Set einstellen
*/
 lcd_enable;
 _delay_ms(5);

 write_data(0x0);     /*Display on/off, Display on, Unterstrich Cursor
on, blinkender Cursor on*/
 lcd_enable;
 _delay_ms(5);
 write_data(0xF);
 lcd_enable;
 _delay_ms(5);

 write_data(0x0);   /* Cursor Home */
 lcd_enable;
 _delay_ms(5);
 write_data(0x2);
 lcd_enable;
 _delay_ms(5);
}

void main(void)
{
 DDRB = 0xFF;
 DDRD = 0xFF;
 init_lcd();
 for(;;);
}

Hoffe mir kann jemand weiterhelfen
Gruß
Martin