Datasheet

ADM1275 Data Sheet
Rev. D | Page 28 of 48
SMBus MESSAGE FORMATS
Figure 58 to Figure 65 show all the SMBus protocols supported
by the ADM1275, 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 ADM1275 is driving the bus.
Figure 58 to Figure 65 use the following abbreviations:
S = start condition
Sr = repeated start condition
P = stop condition
R = read bit
W
= write bit
A = acknowledge bit (0)
A
= acknowledge bit (1)
“A” represents the ACK (acknowledge) bit. The ACK 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
.
SPAAWSLAVE ADDRESS DATA BYTE
S PAAWSLAVE ADDRESS DATA BYTE PEC A
MASTER TO SLAVE
SLAVE TO MASTER
08931-040
Figure 58. Send Byte and Send Byte with PEC
SPAARSLAVE ADDRESS DATA BYTE
S PAARSLAVE ADDRESS DATA BYTE PEC
MASTER TO SLAVE
SLAVE TO MASTER
08931-041
A
Figure 59. Receive Byte and Receive Byte with PEC
SAAWSLAVE ADDRESS COMMAND CODE DATA BYTE PA
SAAWSLAVE ADDRESS COMMAND CODE DATA BYTE
PAPECA
MASTER TO SLAVE
SLAVE TO MASTER
08931-042
Figure 60. Write Byte and Write Byte with PEC
A
SLAVE ADDRESS
R
DATA BYTE
Sr
A
A
S
A
AWSLAVE ADDRESS COMMAND CODE
PA
PEC
SAAWSLAVE ADDRESS COMMAND CODE SLAVE ADDRESS
PRDATA BYTE
Sr
A
MASTER TO SLAVE
SLAVE TO MASTER
08931-043
Figure 61. Read Byte and Read Byte with PEC
P
SAAWSLAVE ADDRESS COMMAND CODE DATA BYTE LOW
A A
SAAWSLAVE ADDRESS COMMAND CODE DATA BYTE LOW
ADATA BYTE HIGH
DATA BYTE HIGH
A
PA
PEC
MASTER TO SLAVE
SLAVE TO MASTER
08931-044
Figure 62. Write Word and Write Word with PEC
SrA SLAVE ADDRESS ARSAWSLAVE ADDRESS COMMAND CODE
ADATA BYTE LOW
PA
A
A
DATA BYTE HIGH
SrA SLAVE ADDRESS ARSAWSLAVE ADDRESS COMMAND CODE
ADATA BYTE LOW
DATA BYTE HIGH
P
PEC
MASTER TO SLAVE
SLAVE TO MASTER
08931-045
Figure 63. Read Word and Read Word with PEC