932SQ420D
PCIE GEN 2/3 & QPI CLOCK FOR ROMLEY-BASED SERVERS
General SMBus Serial Interface Information
How to Write
How to Read
• Controller (host) sends a start bit
• Controller (host) sends the write address
• IDT clock will acknowledge
• Controller (host) will send a start bit
• Controller (host) sends the write address
• IDT clock will acknowledge
• Controller (host) sends the beginning byte location = N
• IDT clock will acknowledge
• Controller (host) sends the beginning byte location = N
• IDT clock will acknowledge
• Controller (host) sends the byte count = X
• IDT clock will acknowledge
• Controller (host) will send a separate start bit
• Controller (host) sends the read address
• IDT clock will acknowledge
• IDT clock will send the data byte count = X
• IDT clock sends Byte N+X-1
• Controller (host) starts sending Byte N through Byte
N+X-1
• IDT clock will acknowledge each byte one at a time
• Controller (host) sends a Stop bit
• IDT clock sends Byte 0 through Byte X (if X was
(H)
written to Byte 8)
• Controller (host) will need to acknowledge each byte
• Controller (host) will send a not acknowledge bit
• Controller (host) will send a stop bit
Index Block Write Operation
Index Block Read Operation
Controller (Host)
starT bit
Slave Address
WR WRite
IDT (Slave/Receiver)
Controller (Host)
starT bit
IDT (Slave/Receiver)
T
T
Slave Address
WR
WRite
ACK
ACK
ACK
ACK
ACK
ACK
Beginning Byte = N
Data Byte Count = X
Beginning Byte N
Beginning Byte = N
RT
Repeat starT
Slave Address
ReaD
RD
ACK
O
O
O
O
O
O
Data Byte Count=X
Beginning Byte N
ACK
ACK
Byte N + X - 1
ACK
O
O
O
P
stoP bit
O
O
O
SMBus write address = D2 hex
SMBus read address = D3 hex
Byte N + X - 1
N
P
Not acknowledge
stoP bit
IDT® PCIE GEN 2/3 & QPI CLOCK FOR ROMLEY-BASED SERVERS
15
932SQ420D
REV H 042012
IDT [ INTEGRATED DEVICE TECHNOLOGY ]
