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IPMI Controller: I2C Interfaces
10006024-04 Katana
®
752i User’s Manual
11-5
In addition to the General Purpose I/O, there are six analog-to-digital (A2D) input pins that
are used for sensing the various power supplies on the board. The following table describes
the Katana
®
752i implementation of these pins.
Table 11-2: Zircon PM Analog-to-Digital Input Pin Functions
I
2
C INTERFACES
The Zircon PM controller supports three I
2
C interfaces. Port 0 is a master/slave interface
which connects to the public IPMB. Port 1 is a master/slave interface which connects to the
I
2
C bus for the MV64460. Port 2 is a master-only interface for accessing the inlet/outlet
temperature sensors and the two IPMI bootloader and boot code ROM devices.
Note: The Zircon PM device must be held in reset when the I2C Port 2 master-only interface is being used by the
750GL processor to access the serial EEPROM devices.
The MV64460 system controller can master Port 2 while the Zircon PM is in reset. This
allows for access to the IPMI serial EEPROMs, which is useful for programming the Zircon
PM application code. An alternate method for accessing the IPMI serial EEPROMs from the
MV64460 is to use IPMI commands on I2C Port 1.
The MV64460 can master Port 1 to send IPMI requests and receive responses from the Zir-
con PM. All IPMI commands supported on the public IPMB are also supported on the private
IPMB.
According to the IPMB specification, IPMI devices must use I
2
C Master Write cycles on the
IPMB. All IPMI messages overlay the I
2
C Master Write data, including the I
2
C command
byte. Using this format, the first byte of an IPMI message transmitted on the bus is also the
I
2
C command byte.
Zircon PM
Pin: Signal Name:
Nominal
Voltage: Function:
A2D1 MON_PMC_3_3V 2.0V connects to the 3.3V PTMC power supply
A2D2 MON_CPU_CORE 1.5V connects directly to the 750GL core power
supply
A2D3 1_8V 1.8V connects directly to the 1.8V power supply
A2D4 MON_2_5V 1.95V connects to the 2.5V power supply via a
resistor divider network
1
1. The A2D inputs on the Zircon PM have a maximum input voltage rating of 2.5V, which is the A2D power
supply voltage. Therefore, any sensed voltage that has a value greater than 2.5V must be divided down.
A2D5 MON_3_3V 2.0 connects to the 3.3V power supply via a
resistor divider network
1
A2D6 MON_5V 1.88V connects to the 5V power supply via a
resistor divider network
1