Global Mixed-mode Technology Inc.
G781
Write Byte Format
S
ADDRESS
WR
ACK
COMMAND
ACK
DATA
8 bits
ACK
P
7 bits
8 bits
1
Slave Address: equivalent to chip- select line of a 3-wire interface
Command Byte: selects which register you are writing to
Data byte: data goes into the register set by the command byte (to set thresholds, configuration masks, and sam
pling rate)
Read Byte Format
S
ADDRESS WR ACK
COMMAND ACK
S
ADDRESS RD
ACK
DATA
8 bits
///
P
7 bits
8bits
7bits
Slave Address: equivalent to chip- select line
Command Byte: selects which register you are reading from
Slave Address: repeated due to change in data-flow direction
Data byte: reads from the register set by the command byte
Send Byte Format
S
ADDRESS
WR
ACK
COMMAND
ACK
P
7 bits
8 bits
Command Byte: sends command with no data , usually used for one-shot command
Receive Byte Format
S
ADDRESS
RD
ACK
DATA
8 bits
///
P
7 bits
Data Byte: reads data from the register commanded by the last Read Byte or Write Byte transmission; also used
for SMBus Alert Response return address
S = Start condition Shaded = Slave transmission P = Stop condition /// = Not acknowledged
Figure 3. SMBus Protocols
Ver: 1.0
TEL: 886-3-5788833
http://www.gmt.com.tw
Oct 02, 2002
8
ETC [ ETC ]
