uint8_t u8g_dev_st7920_128x64_4x_fn(u8g_t *u8g, u8g_dev_t *dev, uint8_t msg, void *arg)
{
  switch(msg)
  {
    case U8G_DEV_MSG_INIT:
      u8g_InitCom(u8g, dev, U8G_SPI_CLK_CYCLE_400NS);
      u8g_WriteEscSeqP(u8g, dev, u8g_dev_st7920_128x64_init_seq);
      break;
    case U8G_DEV_MSG_STOP:
      break;
    case U8G_DEV_MSG_PAGE_NEXT:
      {
        uint8_t y, i;
        uint8_t *ptr;
        u8g_pb_t *pb = (u8g_pb_t *)(dev->dev_mem);
        
        u8g_SetAddress(u8g, dev, 0);           /* cmd mode */
        u8g_SetChipSelect(u8g, dev, 1);
        y = pb->p.page_y0;
        ptr = pb->buf;
        for( i = 0; i < 32; i ++ )
        {
          u8g_SetAddress(u8g, dev, 0);           /* cmd mode */
          u8g_WriteByte(u8g, dev, 0x03e );      /* enable extended mode */

          if ( y < 32 )
          {
                  u8g_WriteByte(u8g, dev, 0x080 | y );      /* y pos  */
                  u8g_WriteByte(u8g, dev, 0x080  );      /* set x pos to 0*/
          }
          else
          {
                  u8g_WriteByte(u8g, dev, 0x080 | (y-32) );      /* y pos  */
                  u8g_WriteByte(u8g, dev, 0x080 | 8);      /* set x pos to 64*/
          }
          
          u8g_SetAddress(u8g, dev, 1);                  /* data mode */
          u8g_WriteSequence(u8g, dev, WIDTH/8, ptr);
          ptr += WIDTH/8;
          y++;
        }
        u8g_SetChipSelect(u8g, dev, 0);
      }
      break;
  }
  return u8g_dev_pb32h1_base_fn(u8g, dev, msg, arg);
}
uint8_t u8g_dev_rrd_st7920_128x64_fn(u8g_t *u8g, u8g_dev_t *dev, uint8_t msg, void *arg) {
  uint8_t i, y;
  switch (msg) {
    case U8G_DEV_MSG_INIT: {
      OUT_WRITE(ST7920_CS_PIN, LOW);
      OUT_WRITE(ST7920_DAT_PIN, LOW);
      OUT_WRITE(ST7920_CLK_PIN, HIGH);

      ST7920_CS();
      u8g_Delay(120);                 //initial delay for boot up
      ST7920_SET_CMD();
      ST7920_WRITE_BYTE(0x20);       //non-extended mode
      ST7920_WRITE_BYTE(0x08);       //display off, cursor+blink off
      ST7920_WRITE_BYTE(0x01);       //clear DDRAM ram
      u8g_Delay(15);                    //delay for DDRAM clear
      ST7920_WRITE_BYTE(0x24);       //extended mode
      ST7920_WRITE_BYTE(0x26);       //extended mode + GDRAM active
      for (y = 0; y < (LCD_PIXEL_HEIGHT) / 2; y++) { //clear GDRAM
        ST7920_WRITE_BYTE(0x80 | y); //set y
        ST7920_WRITE_BYTE(0x80);     //set x = 0
        ST7920_SET_DAT();
        for (i = 0; i < 2 * (LCD_PIXEL_WIDTH) / 8; i++) //2x width clears both segments
          ST7920_WRITE_BYTE(0);
        ST7920_SET_CMD();
      }
      ST7920_WRITE_BYTE(0x0C); //display on, cursor+blink off
      ST7920_NCS();
    }
    break;

    case U8G_DEV_MSG_STOP: break;

    case U8G_DEV_MSG_PAGE_NEXT: {
      uint8_t* ptr;
      u8g_pb_t* pb = (u8g_pb_t*)(dev->dev_mem);
      y = pb->p.page_y0;
      ptr = (uint8_t*)pb->buf;

      ST7920_CS();
      for (i = 0; i < PAGE_HEIGHT; i ++) {
        ST7920_SET_CMD();
        if (y < 32) {
          ST7920_WRITE_BYTE(0x80 | y);       //y
          ST7920_WRITE_BYTE(0x80);           //x=0
        }
        else {
          ST7920_WRITE_BYTE(0x80 | (y - 32)); //y
          ST7920_WRITE_BYTE(0x80 | 8);       //x=64
        }
        ST7920_SET_DAT();
        ST7920_WRITE_BYTES(ptr, (LCD_PIXEL_WIDTH) / 8); //ptr is incremented inside of macro
        y++;
      }
      ST7920_NCS();
    }
    break;
  }
  #if PAGE_HEIGHT == 8
    return u8g_dev_pb8h1_base_fn(u8g, dev, msg, arg);
  #elif PAGE_HEIGHT == 16
    return u8g_dev_pb16h1_base_fn(u8g, dev, msg, arg);
  #else
    return u8g_dev_pb32h1_base_fn(u8g, dev, msg, arg);
  #endif
}