Devices On The Smbus - HP X Class 500/550MHz Reference Manual
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Also See for X Class 500/550MHz:
- User manual (86 pages) ,
- Administrator's manual (118 pages) ,
- Installation manual (60 pages)
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Devices on the SMBus
The SMBus is a subset of the I2C bus. It is a two-wired serial bus which runs at a
maximum speed of 400 kHz. It is used to monitor some of the hardware functions of the
system board (such as voltage levels, temperature, fan speed, DIMM presence and type),
both at system boot and during normal run-time. It is controlled by the SMBus controller
located in the PIIX4E chip.
Table 2-9. Devices on the SMBus
PIIX4E SMBus Master
Processor Data
Serial EEPROM
LM75 (HDD temperature)
Processor Temperature
MaxiLife ASIC
SDRAM Slot 1
SDRAM Slot 2
SDRAM Slot 3
SDRAM Slot 4
PLL
LCD Panel
The following devices are connected to the SMBus:
• PIIX4E SMBus Master Controller 16 kHz maximum.
• DIMM sockets.
• SDRAM clock buffer.
• Serial EEPROM.
• One LM75 temperature sensor.
• MaxiLife for hardware management, bus master controller 400 kHz
maximum.
• LCD status panel.
• CPUs serial EEPROM - Processor Information ROM ("PIROM").
• CPUs thermal sensors.
Chapter 2
Device
System Board
Devices on the SMBus
SMBus Address
10h
EAh, E2h
A8h, AAh
90h
DCh, D8h
28h
A0h
A2h
A4h
A6h
D2h
74h
55
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