void lcd_string(unsigned char x, unsigned char y, char *txt, unsigned char tcol, unsigned char bcol)
{   unsigned char c;
   for(;;)
   {   c=pgm_read_byte(txt++);
      if (!c)
         break;
      lcd_writechar(x,y,c,tcol,bcol);
      x+=2;                            //X - Position um 16 Bit erhöhen
   }
}