Page 21
ETX-EV133
User’s Manual
7.7
System Management Bus and I
2
C
Internally the SMB bus and I
2
C bus are one and the same. The VT82C868B Southbridge sup-
ports only SMBDAT and SMBCLK lines that are I2C compatible.
The X4 connector has pinouts for both I
2
C and SMB bus. Both are connected to the same pins on
the VT82C868B : the I
2
C compatible SMB bus. It is advisable to always connect external (carrier
board) I
2
C devices to the I
2
C pins and SMB devices to the SMB pins to stay compatible with other
modules that might support two internal busses (sperate I
2
C and SMB bus on the Southbridge).
Adresses on the SMB/I
2
C bus already occupied by devices on the module are :
Address
Function
Device
1010 000
Identification Info
SODIMM0
1010 111
CMOS setting backup
EEPROM
inside LAN ID
Control and Status
Ethernet # 1
