Merkwürdiges Phänomen mit Display und SPI

#define LCD_RST    PB3

#define SPI_CS    PB2

#define SPI_MOSI  PB5

#define SPI_SCK    PB7

#define LCD_DC    PB4

#define DISPLAY_PORT PORTB

#define DISPLAY_DDR  DDRB

#define FONT c3x5

#define FONT_POS c3x5_pos

#define  F_CPU 1000000UL

#include <avr/io.h>

#include <util/delay.h>

// unsigned char characters[248] = {0x00,0x5c, 0x06, 0x00, 0x06, 0x28, 0x7c, 0x28, 0x7c, 0x28, 0x5c, 0x54, 0xfe, 0x54, 0x74, 0x44, 0x20, 0x10, 0x08, 0x44, 0x28, 0x54, 0x54, 0x20, 0x50, 0x06, 0x38, 0x44, 0x44, 0x38, 0x02, 0x07, 0x02, 0x10, 0x10, 0x7c, 0x10, 0x10, 0xc0, 0x10, 0x10, 0x10, 0x10, 0x10, 0x40, 0x60, 0x10, 0x0c, 0x7c, 0x64, 0x54, 0x4c, 0x7c, 0x48, 0x7c, 0x40, 0x64, 0x54, 0x54, 0x54, 0x48, 0x44, 0x54, 0x54, 0x54, 0x6c, 0x3c, 0x20, 0x70, 0x20, 0x20, 0x5c, 0x54, 0x54, 0x54, 0x24, 0x7c, 0x54, 0x54, 0x54, 0x74, 0x04, 0x04, 0x64, 0x14, 0x0c, 0x7c, 0x54, 0x54, 0x54, 0x7c, 0x5c, 0x54, 0x54, 0x54, 0x7c, 0x44, 0xc4, 0x10, 0x28, 0x44, 0x28, 0x28, 0x28, 0x28, 0x28, 0x44, 0x28, 0x10, 0x08, 0x04, 0x54, 0x08, 0x7c, 0x44, 0x54, 0x54, 0x5c, 0x7c, 0x24, 0x24, 0x24, 0x7c, 0x7c, 0x54, 0x54, 0x54, 0x6c, 0x7c, 0x44, 0x44, 0x44, 0x44, 0x7c, 0x44, 0x44, 0x44, 0x38, 0x7c, 0x54, 0x54, 0x54, 0x44, 0x7c, 0x14, 0x14, 0x14, 0x04, 0x7c, 0x44, 0x44, 0x54, 0x74, 0x7c, 0x10, 0x10, 0x10, 0x7c, 0x44, 0x44, 0x7c, 0x44, 0x44, 0x60, 0x40, 0x40, 0x44, 0x7c, 0x7c, 0x10, 0x10, 0x28, 0x44, 0x7c, 0x40, 0x40, 0x40, 0x40, 0x7c, 0x08, 0x10, 0x08, 0x7c, 0x7c, 0x08, 0x10, 0x20, 0x7c, 0x38, 0x44, 0x44, 0x44, 0x38, 0x7c, 0x14, 0x14, 0x14, 0x08, 0x3c, 0x24, 0x64, 0x24, 0x3c, 0x7c, 0x14, 0x14, 0x14, 0x68, 0x5c, 0x54, 0x54, 0x54, 0x74, 0x04, 0x04, 0x7c, 0x04, 0x04, 0x7c, 0x40, 0x40, 0x40, 0x7c, 0x0c, 0x30, 0x40, 0x30, 0x0c, 0x3c, 0x40, 0x30, 0x40, 0x3c, 0x44, 0x28, 0x10, 0x28, 0x44, 0x0c, 0x10, 0x60, 0x10, 0x0c, 0x44, 0x64, 0x54, 0x4c, 0x44 };  

// unsigned char character_pos[58] = {0, 1, 4, 9, 14, 19, 24, 25, 27, 29, 32, 37, 38, 43, 44, 47, 52, 55, 60, 65, 70, 75, 80, 85, 90, 95, 96, 97, 100, 105, 108, 112, 117, 122, 127, 132, 137, 142, 147, 152, 157, 162, 167, 172, 177, 182, 187, 192, 197, 202, 207, 212, 217, 222, 227, 232, 237, 242, };

//   

unsigned char c3x5[248] = {0x00, 0x2e, 0x06, 0x06, 0x3e, 0x14, 0x3e, 0x0c, 0x36, 0x18, 0x32, 0x08, 0x26, 0x14, 0x2a, 0x34, 0x06, 0x1c, 0x22, 0x22, 0x1c, 0x14, 0x08, 0x14, 0x08, 0x1c, 0x08, 0x40, 0x60, 0x08, 0x08, 0x08, 0x20, 0x60, 0x1c, 0x03, 0x3e, 0x22, 0x3e, 0x24, 0x3e, 0x20, 0x32, 0x2a, 0x26, 0x22, 0x2a, 0x3e, 0x0e, 0x08, 0x3e, 0x2e, 0x2a, 0x3a, 0x3e, 0x2a, 0x3a, 0x02, 0x3a, 0x06, 0x3e, 0x2a, 0x3e, 0x2e, 0x2a, 0x3e, 0x14, 0x40, 0x64, 0x08, 0x14, 0x22, 0x14, 0x14, 0x14, 0x22, 0x14, 0x08, 0x02, 0x2a, 0x06, 0x3e, 0x22, 0x2e, 0x3e, 0x0a, 0x3e, 0x3e, 0x2a, 0x36, 0x3e, 0x22, 0x22, 0x3e, 0x22, 0x1c, 0x3e, 0x2a, 0x22, 0x3e, 0x0a, 0x02, 0x3e, 0x22, 0x3a, 0x3e, 0x08, 0x3e, 0x22, 0x3e, 0x22, 0x30, 0x20, 0x3e, 0x3e, 0x08, 0x36, 0x3e, 0x20, 0x20, 0x3e, 0x04, 0x3e, 0x3c, 0x08, 0x1e, 0x3e, 0x22, 0x3e, 0x3e, 0x0a, 0x0e, 0x3e, 0x22, 0x7e, 0x3e, 0x0a, 0x34, 0x2e, 0x2a, 0x3a, 0x02, 0x3e, 0x02, 0x3e, 0x20, 0x3e, 0x1e, 0x20, 0x1e, 0x3e, 0x10, 0x3e, 0x36, 0x08, 0x36, 0x06, 0x38, 0x06, 0x32, 0x2a, 0x26};

unsigned char c3x5_pos[58] = {0, 1, 2, 3, 6, 9, 12, 15, 16, 18, 20, 23, 26, 28, 31, 32, 35, 38, 41, 44, 47, 50, 53, 56, 59, 62, 65, 68, 71, 74, 77, 80, 83, 86, 89, 92, 95, 98, 101, 104, 107, 110, 113, 116, 119, 122, 125, 128, 131, 134, 137, 140, 143, 146, 149, 152, 155, 158 };

int main(void)

{

  DISPLAY_DDR = 0xBF;

  DISPLAY_PORT = 0x00;

  DISPLAY_PORT &= ~(1 << LCD_RST);

  _delay_ms(5);

  DISPLAY_PORT |= (1 << LCD_RST);

  //init SPI

  SPCR = (1 << SPE) | (1 << MSTR) | (1 << SPR0);

  display_init();

  //display_c('O');

  display_str("SAM");

    while(1)

    {

    }

}

void display_init(void)

{

  display_out(0x21, 0);

  display_out(0xc0, 0);

  display_out(0x06, 0);

  display_out(0x13, 0);

  display_out(0x20, 0);

  display_clear();

}

void display_out(unsigned char data, unsigned char data_type)

{

  DISPLAY_PORT &= ~(1 << SPI_CS);

  if(data_type)

  {

    DISPLAY_PORT |= (1 << LCD_DC);

  }

  else

  {

    DISPLAY_PORT &= ~(1 << LCD_DC);

  }

  SPDR = data;

  while((SPSR & (1 << SPIF)) == 0);

  DISPLAY_PORT |= (1 << SPI_CS);

}

void display_clear(void)

{

  unsigned int i;

  display_out(0x0c, 0);

  display_out(0x80, 0);

  for(i=0; i<504; i++)

  {

    display_out(0x00, 1);  

  }

}

void display_c(unsigned char c)

{

  unsigned char i;

  unsigned char diff;

  c = c - 0x20;

  if(c > 0)

  {

    diff = FONT_POS[c] - FONT_POS[c-1];

  }

  else

  {

    diff = 1;

  }  

  for(i = 0; i < diff; i++)

  {

    display_out(FONT[FONT_POS[c]-diff+1+i],1);

  }

  display_out(0x00, 1);  

}

void display_str(char *str)

{

  while(*str != '\0')

  {

    display_c(*str);

    str++;

  }

}