Datasheet

AD7992
Rev. 0 | Page 21 of 28
WRITING TO THE AD7992
Depending on the register being written to, there are three
different writes for the AD7992.
WRITING TO THE ADDRESS POINTER REGISTER
FOR A SUBSEQUENT READ
In order to read from a particular register, the address pointer
register must first contain the address of that register. If it does
not, the correct address must be written to the address pointer
register by performing a single-byte write operation, as shown
in Figure 25. The write operation consists of the serial bus
address followed by the address pointer byte. No data is
written to any of the data registers. A read operation can be
subsequently performed to read the register of interest.
WRITING A SINGLE BYTE OF DATA TO THE ALERT
STATUS REGISTER, CYCLE REGISTER, OR
CONFIGURATION REGISTER
The alert status register, cycle register, and configuration
register are all 8-bit registers, so only one byte of data can be
written to each. Writing a single byte of data to one of these
registers consists of the serial bus write address, the chosen
data register address written to the address pointer register,
followed by the data byte written to the selected data register.
See Figure 26.
SDA
START BY
MASTER
ACK. BY
AD7992
ACK. BY
AD7992
STOP BY
MASTER
FRAME 1
SERIAL BUS ADDRESS BYTE
FRAME 2
ADDRESS POINTER REGISTER BYTE
191 9
C4 C3 C2 P2 P1 P0A0A1A2A300
SCL
1
C1
P3
03263-0-006
R/W
Figure 25. Writing to the Address Pointer Register to Select a Register for a Subsequent Read Operation
SDA
ACK. BY
AD7992
119 9
C4 C3 C2 P2 P1 P0
R/W
A0A1A2A300
SCL
1
C1
P3
91 9
D7 D6 D5 D2 D1 D0
D4
D3
FRAME 3
DATA BYTE
SCL (CONTINUED)
SDA (CONTINUED)
03263-0-007
START BY
MASTER
ACK. BY
AD7992
ACK. BY
AD7992
STOP BY
MASTER
FRAME 1
SERIAL BUS ADDRESS BYTE
FRAME 2
ADDRESS POINTER REGISTER BYTE
Figure 26. Single-Byte Write Sequence
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