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

19

1

9

C4

C3

C2

P2

P1

P0

A0

A1

A2

A3

0

0

SCL

1

C1

P3

R/W

Figure 25. Writing to the Address Pointer Register to Select a Register for a Subsequent Read Operation

SDA

ACK. BY

AD7992

11

9

9

C4

C3

C2

P2

P1

P0

R/W

A0

A1

A2

A3

0

0

SCL

1

C1

P3

91

9

D7

D6

D5

D2

D1

D0

D4

D3

FRAME 3

DATA BYTE

SCL (CONTINUED)

SDA (CONTINUED)

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