Maintenance Buses - I2C & FRU-ID
Sun Confidential: Internal Only
39
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Maintenance Buses - I
2
C & FRU-ID
Sun Fire platforms use a global maintenance bus structure to monitor the
environmental integrity of the platform. This monitoring structure is
under control of the system controller and uses a bus architecture called
I
2
C (I squared C).
The I
2
C bus monitors the following:
●
System voltages
●
Temperature
●
Fan speeds
FRU-ID/SEEPROM
The I
2
C bus also functions as the read/write bus for FRU-ID.
The FRU-ID is 8 KBytes of serial electrically erasable programmable read-
only memory (SEEPROM) installed into all FRUs.
This SEEPROM is split into two sections. One is read-only (static), and the
other is read-write (dynamic).
●
The static section of the SEEPROM contains the FRU’s nomenclature,
such as part number, serial number, and manufacturing date.
●
The dynamic section of the SEEPROM is updated by the I
2
C bus
with power-on hours (POH), hot-plug information, plug locations,
and the platform serial number.
This section of the SEEPROM also contains failure information if the
FRU had a hardware fault. This information is for operations use
only (board repair centers).
The only way to extract this information is by using specially
designed utilities that are not available in the field.
