Thermal Sensing Device Supported Smbus Transactions; Write Byte Smbus Packet; Read Byte Smbus Packet; Send Byte Smbus Packet - Intel Itanium 2 Processor Datasheet

THRMALERT# signal (see
register values need to be programmed into the thermal sensing device via the SMBus. It is
recommended that the upper thermal reference threshold byte (provided in the processor
information ROM) be used for setting the upper threshold value in the alarm register.
When polling the thermal sensing device on the processor to read the processor temperatures, it is
recommended that the polling frequency be every 0.5 to 1 second.
6.6 Thermal Sensing Device Supported SMBus
Transactions
The thermal sensing device responds to five of the SMBus packet types: write byte, read byte, send
byte, receive byte, and alert response address (ARA). The send byte packet is used for sending one-
shot commands only. The receive byte packet accesses the register commanded by the last read
byte packet. If a receive byte packet was preceded by a write byte or send byte packet more
recently than a read byte packet, then the behavior is undefined.
diagram the five packet types. In these tables, 'S' represents the SMBus start bit, 'P' represents a
stop bit, 'Ack' represents an acknowledge, and '///' represents a negative acknowledge. The shaded
bits are transmitted by the thermal sensor and the unshaded bits are transmitted by the SMBus host
controller.
Table 6-8. Write Byte SMBus Packet
S Address
1 7 bits
Table 6-9. Read Byte SMBus Packet
S Address
1 7 bits
Table 6-10. Send Byte SMBus Packet
S Address
1 7 bits
Table 6-11. Receive Byte SMBus Packet
S Address
1 7 bits
Table 6-12. ARA SMBus Packet
S
1 0001 100
Datasheet
Section 6.1.1
Table 6-13 shows the encoding of the command byte.
Write Ack Command
1 1
Write Ack Command
1 1
Write Ack Command
1 1
Read Ack
1 1
ARA Read Ack Address
1 1 1001 1011
System Management Feature Specifications
for more details). At power up, the appropriate alarm
Ack Data
8 bits 1 8 bits
Ack S Address
8 bits 1 1 7 bits
Ack P
8 bits 1
Data /// P
8 bits 1 1
/// P
1 1
Table 6-8 through Table 6-12
Ack P
1 1
Read Ack Data
1 1 8 bits
/// P
1 1
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