ADM1024
A read operation is then performed consisting of
the serial bus address, R/W bit set to 1, followed
by the data byte read from the data register. This is
shown in Figure 12.
from the corresponding data register without first
writing to the Address Pointer Register, so
Figure 11 can be omitted.
2. If the Address Pointer Register is known to be
already at the desired address, data can be read
1
9
1
9
SCL
D6
0
1
0
1
A0
D4
D3
D2
D1
SDA
START BY
1
A1
D7
D5
D0
9
R/W
ACK. BY
ADM1024
ACK. BY
ADM1024
MASTER
FRAME 2
FRAME 1
SERIAL BUS ADDRESS BYTE
ADDRESS POINTER REGISTER BYTE
1
SCL (CONTINUED)
SDA (CONTINUED)
D7
D6
D5
D4
D3
D2
D1
D0
ACK. BY STOP BY
ADM1024 MASTER
FRAME 3
DATA BYTE
Figure 10. Writing a Register Address to the Address Pointer Register, then Writing Data to the Selected Register
1
9
1
9
SCL
D7
D6
D5
D4
D3
D2
D1
D0
SDA
0
1
0
1
1
A1
A0
R/W
START BY
MASTER
ACK. BY
ADM1024
ACK. BY STOP BY
ADM1024 MASTER
FRAME 2
FRAME 1
SERIAL BUS ADDRESS BYTE
ADDRESS POINTER REGISTER BYTE
Figure 11. Writing to the Address Pointer Register Only
1
9
1
9
SCL
D6
0
0
1
A0
D4
D3
D2
D1
SDA
START BY
1
1
A1
D7
D5
D0
R/W
ACK. BY
ADM1024
NO ACK. STOP BY
BY MASTER MASTER
MASTER
FRAME 1
SERIAL BUS ADDRESS BYTE
FRAME 2
DATA BYTE FROM ADM1024
Figure 12. Reading Data from a Previously Selected Register
Measurement Inputs
NOTES
The ADM1024 has nine external measurement pins that can
be configured to perform various functions by programming
the Channel Mode Register.
Pins 13 and 14 are dedicated to temperature measurement,
while Pins 15, 16, and 19 are dedicated analog input channels.
Their function is unaffected by the Channel Mode Register.
Pins 5 and 6 can be individually programmed as analog
inputs, or as digital fan speed measurement inputs, by
programming Bits 0 and 1 of the Channel Mode Register.
Bit 3 of the Channel Mode Register configures the internal
1. Although it is possible to read a data byte from a
data register without first writing to the Address
Pointer Register, if the Address Pointer Register is
already at the correct value, it is not possible to
write data to a register without writing to the
Address Pointer Register because the first data
byte of a write is always written to the Address
Pointer Register.
2. In Figure 10 to Figure 12, the serial bus address is
shown as the default value 01011(A1)(A0), where
A1 and A0 are set by the three−state ADD pin.
V
CC
measurement range for either 3.3 V or 5.0 V.
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10
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