Chapter 2
55
System Board
Devices on the SMBus
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.
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.
Table 2-9. Devices on the SMBus
Device
SMBus Address
PIIX4E SMBus Master
10h
Processor Data
EAh, E2h
Serial EEPROM
A8h, AAh
LM75 (HDD temperature)
90h
Processor Temperature
DCh, D8h
MaxiLife ASIC
28h
SDRAM Slot 1
A0h
SDRAM Slot 2
A2h
SDRAM Slot 3
A4h
SDRAM Slot 4
A6h
PLL
D2h
LCD Panel
74h
Содержание X Class 500/550MHz
Страница 6: ...6 Contents ...
Страница 8: ...8 Figures ...
Страница 15: ...15 1 System Overview ...
Страница 66: ...66 Chapter2 System Board Devices on the ISA Bus ...
Страница 96: ...96 Chapter3 Interface Boards and Mass Storage Drivers Connectors and Sockets ...
Страница 134: ...134 Chapter5 Tests and Error Messages Beep Codes ...
Страница 135: ...135 A Regulatory Information and Warranty ...
Страница 146: ...146 AppendixA Regulatory Information and Warranty HP Hardware Warranty ...