TC1321
Write 1-Byte Format
S
Address
7-Bits
Slave Address
Write 2-Byte Format
R/W ACK Command
ACK Data ACK P
0
8-Bits
8-Bits
Command Byte: selects
which register you are
writing to.
Data Byte: data goes
into the register set
by the command byte.
S
Address
R/W ACK Command
ACK Data ACK Data ACK P
7-Bits
0
8-Bits
8-Bits
8-Bits
Slave Address
Command Byte: selects
which register you are
writing to.
Data Byte: data goes
into the register set
by the command byte.
Read 1-Byte Format
S Address R/W ACK Command ACK S Address R/W ACK Data NACK P
7-Bits 0
8-Bits
7-Bits 1
8-Bits
Slave Address
Command Byte: selects Slave Address: repeated Data Byte: reads from
which register you are due to change in data the register set by the
reading from.
flow direction.
command byte.
Read 2-Byte Format
S Address R/W ACK Command ACK S Address R/W ACK Data ACK Data NACK P
7-Bits 0
8-Bits
7-Bits 1
8-Bits
8-Bits
Slave Address
Command Byte: selects
which register you are
reading from.
Slave Address: repeated Data Byte: reads from
due to change in data the register set by the
flow direction.
command byte.
Receive 1-Byte Format
S Address R/W ACK Data NACK P
7-Bits 1
8-Bits
S = START Condition
Data Byte: reads data from
P = STOP Condition
the register commanded by
Shaded = Slave Transmission the last read-byte or write-
byte transmission.
Receive 1-Byte Format
S Address R/W ACK Data ACK Data NACK P
7-Bits 1
8-Bits
8-Bits
S = START Condition
P = STOP Condition
Shaded = Slave Transmission
Data Byte: reads data from
the register commanded by
the last read-byte or write-
byte transmission.
FIGURE 3-1:
SMBus/I2C Protocols.
DS21387C-page 8
2010 Microchip Technology Inc.