ADM1032
1
9
1
9
SCLK
D6
D5
D4
D3
D2
D1
D0
A6
A5
A4
A3
A2
A1
A0
R/W
D7
SDATA
START BY
MASTER
ACK. BY
ADM1032
ACK. BY
ADM1032
FRAME 2
FRAME 1
ADDRESS POINTER REGISTER BYTE
SERIAL BUS ADDRESS BYTE
1
9
SCLK (CONTINUED)
SDATA (CONTINUED)
D2
D7
D6
D5
D4
D3
D1
D0
ACK. BY STOP BY
ADM1032 MASTER
FRAME 3
DATA BYTE
Figure 13. Writing a Register Address to the Address Pointer Register,
then Writing Data to the Selected Register
1
9
1
9
SCLK
A6
A5
A4
A3
A2
A1
A0 R/W
D7
D6
D5
D4
D3
D2
D1
D0
SDATA
ACK. BY
ADM1032
ACK. BY STOP BY
ADM1032 MASTER
START BY
MASTER
FRAME 1
SERIAL BUS ADDRESS BYTE
FRAME 2
ADDRESS POINTER REGISTER BYTE
Figure 14. Writing to the Address Pointer Register Only
19
1
9
SCLK
SDATA
START BY
A6
A5
A4
A3
A2
A1
A0
R/W
ACK. BY
D7
D6
D5
D4
D3
D2
D1
D0
ACK. BY STOP BY
ADM1032 MASTER
ADM1032
MASTER
FRAME 1
SERIAL BUS ADDRESS BYTE
FRAME 2
DATA BYTE FROM ADM1032
Figure 15. Reading Data from a Previously Selected Register
MASTER
RECEIVES
SMBALERT
ALERT Output
The ALERT output goes low whenever an out−of−limit
measurement is detected, or if the remote temperature sensor
is open−circuit. It is an open drain and requires a pullup to
ALERT RESPONSE
ADDRESS
DEVICE
ADDRESS
NO
ACK
START
RD ACK
STOP
MASTER SENDS
ARA AND READ
COMMAND
V
DD
. Several ALERT outputs can be wire−OR’ed together
DEVICE SENDS
ITS ADDRESS
so that the common line goes low if one or more of the
ALERT outputs goes low.
Figure 16. Use of SMBALERT
The ALERT output can be used as an interrupt signal to a
processor, or it can be used as an SMBALERT. Slave devices
on the SMBus can not normally signal to the master that they
want to talk, but the SMBALERT function allows them to do
so.
One or more ALERT outputs can be connected to a
common SMBALERT line connected to the master. When
the SMBALERT line is pulled low by one of the devices, the
following procedure occurs (see Figure 16).
1. SMBALERT is pulled low.
2. Master initiates a read operation and sends the
alert response address (ARA = 0001 100). This is
a general call address that must not be used as a
specific device address.
3. The device whose ALERT output is low responds
to the alert response address and the master reads
its device address. Since the device address is
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