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
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
ACK
YYYY_YYYb
REGISTER
DATA
0
ACK
0
REGISTER
DATA
XXh
ACK
0
REGISTER
DATA
1 ->0
ACK
YYYY_YYYb
...
1
REGISTER
DATA
0
NACK
XXh
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 Alert Response Address Protocol
ALERT
RESPONSE
ADDRESS
0001_100b
START
1 -> 0
RD
1
ACK
0
DEVICE
ADDRESS
YYYY_YYYb
NACK
1
STOP
0 -> 1
The EMC2301 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 EMC2301
15
Revision 1.1 (10-12-09)
DATASHEET
SMSC [ SMSC CORPORATION ]
