probleme mit "0" und strings/arrays

void sendCmd(uint8_t cmdindex, uint8_t *param)

{

  char dsplout[MAXLEN];

  uint32_t chksum = 0;

  uint8_t index = 0;

  uint8_t len = 3;

  chksum = 0;

  dsplout[index] = DC1;

  chksum = chksum + dsplout[index++];

  dsplout[++index] = ESC;

  chksum = chksum + dsplout[index];

  dsplout[++index] =commands[cmdindex][0];

  chksum = chksum + dsplout[index];

  dsplout[++index] =commands[cmdindex][1];

  chksum = chksum + dsplout[index];

  while(*param)

  {

    dsplout[++index] = *param++;

    chksum = chksum + dsplout[index];

    len++;

    PORTB |= (1<<PB6);

    _delay_ms(20);

    PORTB &= ~(1<<PB6);

    _delay_ms(20);

  }

  chksum = chksum + len;

  chksum = chksum % 256;

  dsplout[1] = len;

  //dsplout[6] = '3';

  dsplout[++index] = chksum;

  dsplout[++index] = '\0';

  sendChar(dsplout);

}

void setPicture(char num, uint16_t xpos, uint16_t ypos)

{

   uint8_t val[5];

   val[0] = 1;//xposlbyte

   val[1] = 0;//xposhbyte

   val[2] = 1;//yposlbyte

   val[3] = 0;//yposhbyte

   val[4] = 1;

   sendCmd(CMD_SETPICTURE, val, sizeof(val));

}