Multiple RPM-Based PWM Fan Controller for Five Fans
Datasheet
3.2.4
Receive Byte
The Receive Byte protocol is used to read data from a register when the internal register address
pointer is known to be at the right location (e.g. set via Send Byte). This is used for consecutive reads
of the same register as shown in Table 3.6.
Table 3.6 Receive Byte Protocol
SLAVE
START
1 -> 0
ADDRESS
RD
ACK
REGISTER DATA
NACK
STOP
YYYY_YYYb
1
0
XXh
1
0 -> 1
3.2.5
Block Write Protocol
The Block Write is used to write multiple data bytes to a group of contiguous registers as shown in
Table 3.7. It is an extension of the Write Byte Protocol.
Table 3.7 Block Write Protocol
SLAVE
ADDRESS
REGISTER
ADDRESS
REGISTER
DATA
START
WR
ACK
ACK
ACK
1 ->0
YYYY_YYYb
0
0
XXh
0
XXh
0
REGISTER
DATA
REGISTER
DATA
REGISTER
DATA
ACK
ACK
. . .
ACK
STOP
XXh
0
XXh
0
. . .
XXh
0
0 -> 1
3.2.6
Block Read Protocol
The Block Read is used to read multiple data bytes from a group of contiguous registers as shown in
Table 3.8. It is an extension of the Read Byte Protocol.
Table 3.8 Block Read Protocol
START
SLAVE
ADDRESS
WR
ACK
REGISTER
ADDRESS
ACK
START
SLAVE
ADDRESS
RD
ACK
REGISTER
DATA
1->0
YYYY_YYYb
0
0
XXh
0
1 ->0
YYYY_YYYb
1
0
XXh
ACK
REGISTER
DATA
ACK
REGISTER
DATA
ACK
REGISTER
DATA
ACK
. . .
REGISTER
DATA
NACK
STOP
0
XXh
0
XXh
0
XXh
0
. . .
XXh
1
0 -> 1
3.2.7
Alert Response Address
The ALERT# output can be used as a processor interrupt or as an SMBus Alert when configured to
operate as an interrupt.
When it detects that the ALERT# pin is asserted, the host will send the Alert Response Address (ARA)
to the general address of 0001_100xb. All devices with active interrupts will respond with their client
address as shown in Table 3.9.
Revision 1.1 (10-12-09)
SMSC EMC2305
DATA1S6HEET
SMSC [ SMSC CORPORATION ]
