Organization of the Board
MEN Mikro Elektronik GmbH
42
20BC50R00 E1 – 2015-09-07
4.3
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 17.
SMB address space
User LED Signals (0x40)
Table 18.
SMB 0x40
Address
Function
0xAC
EEPROM, includes system information e.g. serial
number and the date of production.
0x40
I/O Expander, used to activate the ignition signal, the
photocouplers and the binary inputs, reset the watchdog
and control user LEDs A and B at the front panel.
0x42
I/O Expander, used to control user LED C at the front
panel, power cycle the PCIe Mini Cards and to switch
between the connected SIM cards.
Bit
Direction
Signal
Default
Value
Description
Group
7
In
IGNITION_I
SO
-
Bit to read back the ignition status.
System
0 =
Setting this bit to '0' results in the
same behavior as deactivating the
external ignition signal (power
button event, starting the
watchdog timer)
1 =
If the bit is '1' the ignition signal is
active.
