Datasheet

ADM1276 Data Sheet
Rev. C | Page 26 of 48
Sr
A
SL
A
VE
ADDRESS
A
R
S
AW
SL
AVE
ADDRESS COMMAND CODE
A
D
AT
A
BYTE LOW
P
A
A
A
D
AT
A
BYTE HIGH
SrA
SL
A
VE
ADDRESS
A
R
S
A
W
SL
A
VE
ADDRESS
COMMAND CODE
A
D
ATA
BYTE LOW
D
AT
A
BYTE HIGH
P
PEC
MASTER
T
O SLA
VE
SL
A
VE T
O MASTER
09718-057
Figure 57. Read Word and Read Word with PEC
Sr
A
SL
A
VE
ADDRESS
AR
S A
WSLAVE ADDRESS COMMAND CODE
A
BYTE COUNT = N
A
DATA BYTE 1
P
D
AT
A
BYTE N
A
D
AT
A
BYTE 2
Sr
A
SLA
VE
ADDRESS ARS A
W
SLAVE ADDRESS COMMAND CODE
A
BYTE COUNT = N
A
D
ATA BYTE 1
A
DAT
A
BYTE N PPEC
A
D
AT
A BYTE 2
MASTER TO SL
AVE
SL
AVE
TO MASTER
A
A
09718-058
Figure 58. Block Read and Block Read with PEC
MASTER T
O SLA
VE
SLAVE TO MASTER
A LOW DATA BYTE
AS AWDEVICE 1 ADDRESS COMMAND CODE 1
AHIGH DATA BYTE
ONE OR MORE DATA BYTES
A LOW DATA BYTE
ASr A
WDEVICE 2 ADDRESS COMMAND CODE 2
AHIGH DATA BYTE
ONE OR MORE DATA BYTES
A LOW DATA BYTE ASr AWDEVICE N ADDRESS COMMAND CODE N
A P
HIGH DAT
A BYTE
ONE OR MORE DATA BYTES
09718-059
Figure 59. Group Command
MASTER
TO SLA
VE
SLA
VE TO MASTER
A
PEC 1
P
A
LOW D
ATA
BYTE
A
S AW
DEVICE 1 ADDRESS
COMMAND CODE 1
AHIGH DATA BYTE
ONE OR MORE DAT
A BYTES
APEC 2
A LOW DATA BYTE
A
Sr A
WDEVICE 2 ADDRESS COMMAND CODE 2
A
HIGH D
AT
A BYTE
ONE OR MORE DATA
BYTES
A
PEC N
A LOW D
ATA BYTE
A
Sr A
WDEVICE N ADDRESS COMMAND CODE N
A
HIGH DATA
BYTE
ONE OR MORE DAT
A BYTES
09718-060
Figure 60. Group Command with PEC
GROUP COMMANDS
The PMBus standard defines what are known as group commands.
Group commands are single bus transactions that send commands
or data to more than one device at the same time. Each device is
addressed separately, using its own address; there is no special
group command address. A group command transaction can
contain only write commands that send data to a device. It is
not possible to use a group command to read data from devices.
From an I
2
C protocol point of view, a normal write command
consists of the following:
• I
2
C start condition.
• Slave address bits and a write bit (followed by an
acknowledge from the slave device).
• One or more data bytes (each of which is followed by an
acknowledge from the slave device).
• I
2
C stop condition to end the transaction.