MSI 939-9A79-002, Manual, Page: 71 / 72

A-5
GPIO WDT BKL Programming MS-9A79
LVDS Backlight Brightness Control
3. LVDS Backlight Brightness Control
The LVDS controller support 17 level of backlight brightness value from 0 (30%) to 16
(100%) and it is accessible through SMBus. The associated access method
( SMBus_ReadByte , SMBus_WriteByte ) are provided in part 4.
3.1 Set the Level of LVDS Backlight
1. Write 0xED into address 0x7F on SMBus device 0x42 .
2. Write desired backlight level from 0x0 (30%) to 0x10 (100%) into address 0x6E on
SMBus device 0x42 .
Example: Set LVDS backlight level to 0x10 (100%)
SMBus_WriteByte (0x42, 0x7F, 0xED);
SMBus_WriteByte (0x42, 0x6E, 0x10 ); // Set brightness to 100%
3.2 Read the Level of LVDS Backlight
1.Write 0xED into address 0x7F on SMBus device 0x42 .
2.Read current backlight level from address 0x6E on SMBus device 0x42 .
Example: Get LVDS backlight level
SMBus_WriteByte (0x42, 0x7F, 0xED);
BKL_Value = SMBus_ReadByte (0x42, 0x6E);