Dual RPM-Based PWM Fan Controller
Datasheet
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 3.7. It is an extension of the Read Byte Protocol.
Table 3.7 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 3.8.
Table 3.8 Alert Response Address Protocol
ALERT
RESPONSE
ADDRESS
DEVICE
ADDRESS
START
1 -> 0
RD
ACK
NACK
STOP
0001_100b
1
0
YYYY_YYYb
1
0 -> 1
The EMC2302 will respond to the ARA in the following way if the ALERT# pin is asserted.
1. Send Slave Address and verify that full slave address was sent (i.e. the SMBus communication
from the device was not prematurely stopped due to a bus contention event).
2. Set the MASK bit to clear the ALERT# pin.
SMSC EMC2302
Revision 1.1 (10-12-09)
DATA1S5HEET
SMSC [ SMSC CORPORATION ]
