EMC2301 Datasheet, PDF (15/42 Pages) SMSC Corporation – RPM-Based PWM Fan Controller

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.
START
SLAVE
WR
ADDRESS
1->0 YYYY_YYYb
0
ACK
REGISTER
DATA
ACK
0
XXh
0
ACK
0
REGISTER
DATA
XXh
Table 3.7 Block Read Protocol
REGISTER
ADDRESS
XXh
ACK
0
ACK
START
0
REGISTER
DATA
XXh
1 ->0
ACK
0
SLAVE
ADDRESS
YYYY_YYYb
...
...
RD
1
REGISTER
DATA
XXh
ACK
0
NACK
1
REGISTER
DATA
XXh
STOP
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.
START
1 -> 0
Table 3.8 Alert Response Address Protocol
ALERT
RESPONSE
ADDRESS
0001_100b
DEVICE
RD
ACK
ADDRESS
1
0
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
DATASHEET
Revision 1.1 (10-12-09)