Fan Control Device with Hardware Monitoring and Acoustic Noise Reduction Features
Datasheet
Write Byte
The Write Byte protocol is used to write data to the registers. The data will only be written if the protocol
shown in Table 4.2 is performed correctly. Only one byte is transferred at time for a Write Byte protocol.
Table 4.2 SMBus Write Byte Protocol
FIELD
Bits
START
SLAVE ADDR
WR
ACK
REG. ADDR
ACK
REG. DATA
ACK
STOP
1
7
1
1
8
1
8
1
1
Read Byte
The Read Byte protocol is used to read data from the registers. The data will only be read if the
protocol shown in Table 4.3 is performed correctly. Only one byte is transferred at time for a Read Byte
protocol.
Table 4.3 SMBus Read Byte Protocol
SLAVE
ADDR
REG.
SLAVE
ADDR
REG.
FIELD:
Bits:
START
WR
ACK
ADDR
ACK
START
RD
ACK
DATA
NACK
STOP
1
7
1
1
8
1
1
7
1
1
8
1
1
4.4
Invalid Protocol Response Behavior
Registers that are accessed with an invalid protocol will not be updated. A register will only be updated
following a valid protocol. The only valid protocols are the Write Byte and Read Byte protocols, which
are described above.
The EMC6D102 device responds to three SMBus slave addresses:
1. The SMBus slave address that supports the valid protocols defined in the previous sections is
determined by the level on the Address Select and Address Enable pins as shown in Section 4.1,
"Slave Address," on page 13.
2. SMBus Alert Response (0001 100). The SMBus will only respond to the SMBus Alert Response
Address if the SMBus Alert Response interrupt was generated to request a response from the Host.
The SMBus Alert Response is defined in Section 4.10, "SMBus Alert Response Address," on
page 16.
Attempting to communicate with the Hardware Monitor Block over SMBus with an invalid slave
address, or invalid protocol will result in no response, and the SMBus Slave Interface will return to the
idle state.
The only valid registers that are accessible by the SMBus slave address are the registers defined in
the Registers Section. See Section 4.4.1, "Undefined Registers" for response to undefined registers.
4.4.1
Undefined Registers
Reads to undefined registers return 00h. Writes to undefined registers have no effect and return no
error.
4.5
General Call Address Response
The EMC6D102 will not respond to a general call address of 0000_000.
SMSC EMC6D102
Revision 0.4 (04-05-05)
DATA1S5HEET
SMSC [ SMSC CORPORATION ]
