
932S890C
RD890 SYSTEM CLOCK FOR AMD-BASED SERVERS
IDT
RD890 SYSTEM CLOCK FOR AMD-BASED SERVERS
12
932S890C
REV D 052011
General SMBus Serial Interface Information
How to Write
Controller (host) sends 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 byte count = X
IDT clock will acknowledge
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
How to Read
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) 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
IDT clock sends Byte 0 through Byte X (if X(H) was
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
Controller (Host)
IDT (Slave/Receiver)
TstarT bit
Slave Address
WR
WRite
ACK
Beginning Byte = N
ACK
Data Byte Count = X
ACK
Beginning Byte N
X
B
y
te
ACK
O
Byte N + X - 1
ACK
PstoP bit
Read Address
Write Address
D3(H)
D2(H)
Index Block Read Operation
Controller (Host)
IDT (Slave/Receiver)
TstarT bit
Slave Address
WR
WRite
ACK
Beginning Byte = N
ACK
RT
Repeat starT
Slave Address
RD
ReaD
ACK
Data Byte Count=X
ACK
X
By
te
Beginning Byte N
ACK
O
Byte N + X - 1
N
Not acknowledge
PstoP bit