82870P2P64H2 Datasheet, PDF (167/217 Pages) –

Functional Description
R
These attributes are shown in Figure 11.
Figure 11. Flow Diagram for SMBus
Begin
End
W ait for Stop or
Start Repeat Bits
Start + Slave Address
+ Direction Received
Intel^®
No
P64H2
Hit?
Yes
Send NACK
Yes
Busy?
No
W rite
Yes
Direction?
Register Index
No
Received
Send ACK,
Increment Ponter
Send byte pointed to
by Register Index
(note 1)
Send ACK
Ack
Received? ^No
Yes
No _{Last Byte?}
Yes
Send STOP
Bit
Yes
Perform Operation
in Command
Register
Stop
Received?
No
Start
Repeat Yes
Received?
No
Receive Next
Byte, write into
Register Pointed
to by Index
Register (Note 2)
End
Send ACK,
Increment Pointer
smbus_flow
Note:
1. If this is the first byte of the read, and the P64H2 is in ICH mode (bit 0 of offset FFh set), then
the first data the P64H2 will return is 04h, and the Index Register does not increment.
Subsequent data will be the data pointed to by the Index Register.
2. If this is the first byte received after the index, and the P64H2 is in ICH mode (bit 0 of FFh
set), then the first data the P64H2 receives will be the byte count from the ICH - the P64H2
should discard this data and not increment the index register. Subsequent data will be real
data.
Intel^® 82870P2 P64H2 Datasheet
167