EMC1422 SMSC Corporation, EMC1422 Datasheet - Page 12

• Manufacturer Part Number: EMC1422
• Description: 1C Temperature Sensor
• Manufacturer: SMSC Corporation

Chapter 4 System Management Bus Interface Protocol
.
Revision 1.16 (03-15-07)
4.1
4.2
START
SMCLK
SMDTA
1
System Management Bus Interface Protocol
Write Byte
The EMC1422 communicates with a host controller, such as an SMSC SIO, through the SMBus. The
SMBus is a two-wire serial communication protocol between a computer host and its peripheral
devices. A detailed timing diagram is shown in
The EMC1422 is SMBus 2.0 compatible and support Send Byte, Read Byte, Write Byte, Receive Byte,
and the Alert Response Address as valid protocols as shown below.
All of the below protocols use the convention in
Attempting to communicate with the EMC1422 SMBus interface with an invalid slave address or invalid
protocol will result in no response from the device and will not affect its register contents. Stretching
of the SMCLK signal is supported, provided other devices on the SMBus control the timing.
The Write Byte is used to write one byte of data to the registers as shown below
ADDRESS
P
SLAVE
T
BUF
7
S
T
T
S - Start Condition
HD:STA
LOW
WR
1
T
HD:DAT
T
RISE
Figure 4.1 SMBus Timing Diagram
# of bits sent
DATA SENT
ACK
TO DEVICE
T
Table 4.2 Write Byte Protocol
1
HIGH
Table 4.1 Protocol Format
DATASHEET
T
SU:DAT
T
REGISTER
ADDRESS
FALL
12
8
DATA SENT TO
# of bits sent
THE HOST
Figure
Table
1°C Temperature Sensor with Hardware Thermal Shutdown
4.1.
4.1.
S
ACK
1
T
T
SU:STA
HD:STA
REGISTER
DATA
P - Stop Condition
8
T
SU:STO
Table
ACK
1
SMSC EMC1422
4.2:
P
Datasheet
STOP
1