Controlling the System via SMBus
MEN Mikro Elektronik GmbH
63
20BL50S00 E2 – 2014-12-10
4.2
SMBus Register Description
The SMB address is compliant to the Windows nomenclature. This means that the
last bit which is used as the read/write bit is added with the value '0' to the address.
Under Linux a 0 is added at the beginning of the address so that all consecutive
address bits are moved one bit to the right.
Example
Binary address of the I/O-Expander with hard coded offset 0b 0100 and chosen
address bits:
• 0b 0100 (A2)(A1)(A0)(R/W)
With address bits:
• 0b 0100 010 (R/W)
Windows address:
• (R/W) = 0 -> 0b 0100 0100 ->
0x44
Linux address:
• 0b 0010 0010 ->
0x22
Table 19.
SMB address space
Address
Function
0xC0
PoE PIC, used to control the PoE interface, can be used
to switch on/off connected PoE devices.
0xAC
EEPROM, includes system information e.g. serial
number and the date of production.
0x40
I/O Expander, used to power cycle the PCIe Mini Card, to
switch between the connected SIM cards, reset the
Watchdog, read back the ignition status and to control
the user LEDs at the front panel.
