Datasheet

Dual-Core Intel
®
Itanium
®
Processor 9000 and 9100 Series Datasheet 87
System Management Feature Specifications
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. Table 6-8 through Table 6-12 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 6-13 shows the encoding of the command byte.
Table 6-8. Write Byte SMBus Packet
SAddressWriteAck Command Ack Data Ack P
17 bits 1
18 bits18 bits11
Table 6-9. Read Byte SMBus Packet
SAddressWriteAck Command Ack S Address Read Ack Data
//
/
P
17 bits 0
18 bits117 bits 1 1 8 bits 1 1
Table 6-10. Send Byte SMBus Packet
SAddressWriteAck Command Ack P
17 bits 1
18 bits1
Table 6-11. Receive Byte SMBus Packet
SAddressReadAck Data /// P
17 bits 1
1 8 bits 1 1
Table 6-12. ARA SMBus Packet
SARAReadAck Address /// P
1 0001 100 1
1 1001 1011 1 1