Datasheet

Data Sheet ADM1276
Rev. C | Page 25 of 48
SMBus MESSAGE FORMATS
Figure 52 to Figure 60 show all the SMBus protocols supported
by the ADM1276, along with the PEC variant. In these figures,
unshaded cells indicate that the bus host is actively driving the
bus; shaded cells indicate that the ADM1276 is driving the bus.
Figure 52 to Figure 60 use the following abbreviations:
S is the start condition.
Sr is the repeated start condition.
P is the stop condition.
R is the read bit.
W
is the write bit.
A is the acknowledge bit (0).
A
is the acknowledge bit (1).
“A” represents the acknowledge bit. The acknowledge bit is typi-
cally active low (Logic 0) if the transmitted byte is successfully
received by a device. However, when the receiving device is the
bus master, the acknowledge bit for the last byte read is a Logic 1,
indicated by
A
.
S
PAAW
SLA
VE
ADDRESS DATA BYTE
S
PA
A
WSLAVE ADDRESS D
AT
A BYTE
PEC
A
MASTER T
O SLA
VE
SLA
VE T
O MASTER
09718-052
Figure 52. Send Byte and Send Byte with PEC
S PAARSLAVE ADDRESS DATA BYTE
S PAARSL
AVE ADDRESS DATA BYTE PEC
MASTER TO SLAVE
SLAVE TO MASTER
A
09718-053
Figure 53. Receive Byte and Receive Byte with PEC
S AAWSLAVE ADDRESS COMMAND CODE DATA BYTE
PA
S AAWSLAVE ADDRESS COMMAND CODE DATA BYTE
PA PEC A
MASTER TO SLAVE
SLAVE TO MASTER
09718-054
Figure 54. Write Byte and Write Byte with PEC
A
SLAVE ADDRESS
R
DATA BYTE
Sr
A
A
S
A
AWSLAVE ADDRESS COMMAND CODE
PA
PEC
S AAWSLAVE ADDRESS COMMAND CODE SLAVE ADDRESS
PR DATA BYTE
Sr
A
MASTER TO SLAVE
SLAVE TO MASTER
09718-055
Figure 55. Read Byte and Read Byte with PEC
P
S AAWSLA
VE ADDRESS COMMAND CODE DATA BYTE LOW
A
A
S AA
WSLAVE ADDRESS COMMAND CODE DATA BYTE LOW
A DATA BYTE HIGH
DATA BYTE HIGH
A
PA
PEC
MASTER TO SLAVE
SLAVE TO MASTER
09718-056
Figure 56. Write Word and Write Word with PEC