CP302
Functional Description and Configuration
ID 21112, Rev. 05
Page 2 - 11
®
PEP Modular Computers GmbH
2.5.4
SMBus Devices
The CP302 provides a System Management Bus (SMBus) for access to several system
monitoring and configuration functions. The SMBus consists of a two-wire I2C bus
interface. The following table describes the function and address of every onboard
SMBus device.
2.5.5
Thermal Management / System Monitoring
The LM81 can be used to monitor several critical hardware parameters of the system,
including power supply voltages, fan speeds and temperatures; all of which are very
important for the proper operation and stability of a high-end computer system. The
LM81 provides an I2C
™
serial bus interface.
The voltages of the onboard power supply (+12 V, -12V, +5V, +3.3V, +1.5V, Vcore) are
supervised. The onboard hardware monitor is able to detect the CPU fan speed and an
external fan speed in revolutions per minute (RPM). The presence of the fans is
automatically detected.
The integrated MAX1617 temperature sensors monitor the CPU temperature to make
sure that the system is operating at a safe temperature level. If the temperature is too
high, the sensors automatically reduces the CPU clock frequency, depending on the
mode chosen in the BIOS set.
Table 2-2: SMBus Device Addresses
Device
SMB Address
PIIX4 slave port
0001000Xb
Temperature sensor MAX1617
0011000Xb
Hardware Monitor LM81
0101100Xb
EEPROM
1010XXXXb
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com