SMBus Interface
Figure 7-4. SMBus Configuration Double Word Write (Write Bytes, PEC Enabled)
S
S
S
S
S
S
S
S
X011_XXX
X011_XXX
X011_XXX
X011_XXX
X011_XXX
X011_XXX
X011_XXX
X011_XXX
W
W
W
W
W
W
W
W
A
A
A
A
A
A
A
A
Cmd = 10011100
Cmd = 00011100
Cmd = 00011100
Cmd = 00011100
Cmd = 00011100
Cmd = 00011100
Cmd = 00011100
Cmd = 01011100
A
A
A
A
A
A
A
A
Reserved
Device/Function
Register[15:8]
Register[7:0]
Data[31:24]
Data[23:16]
Data[15:8]
A
A
A
A
A
A
A
A
PEC
PEC
PEC
PEC
PEC
PEC
PEC
PEC
A
A
A
A
A
A
A
A
P
P
P
P
P
P
P
P
Data[7:0]
Figure 7-5. SMBus Configuration Word Write (Block Write, PEC Disabled)
A
ByteCount =6
A
Reserved
A
Device/Function
Data[16:8]
A
Reg Number[15:8]
Data[7:0]
A
Reg Number [7:0]
S
X011_XXX
WA Cmd = 11001010
A
A
A P
Figure 7-6. SMBus Configuration Byte Write (Write Bytes, PEC Disabled)
S
S
S
S
S
X011_XXX
X011_XXX
X011_XXX
X011_XXX
X011_XXX
W
W
W
W
W
A
A
A
A
A
Cmd = 10000100
Cmd = 00000100
Cmd = 00000100
Cmd = 00000100
Cmd = 01000100
A
A
A
A
A
Reserved
Device/Function
Register[15:8]
Register[7:0]
Data[7:0]
A
A
A
A
A
P
P
P
P
P
7.1.4
SMBus Error Handling
The SMBus slave interface handles two types of errors: internal and PEC. These errors
manifest as a Not-Acknowledge (NACK) for the read command (End bit is set). If an
internal error occurs during a configuration write, the final write command receives a
NACK just before the stop bit. If the master receives a NACK, the entire configuration
transaction should be reattempted.
If the master supports packet error checking (PEC) and the PEC_en bit in the command
is set, then the PEC byte is checked in the slave interface. If the check indicates a
failure, then the slave will NACK the PEC packet.
7.1.5
SMBus Resets
7.1.5.1
SMBus Transactions During FBD Link Fast Reset
When the FBD link transitions into Electrical Idle (disable state) from an active state,
this causes a “fast” reset of all non-sticky registers in the AMB. SMB transactions
underway during a “fast” reset will not complete normally.
Intel® 6400/6402 Advanced Memory Buffer Datasheet
81
INTEL [ INTEL ]
