Datasheet

AD7730/AD7730L
–21–
READING FROM AND WRITING TO THE ON-CHIP REGISTERS
The AD7730 contains a total of thirteen on-chip registers. These registers are all accessed over a three-wire interface. As a result,
addressing of registers is via a write operation to the topmost register on the part, the Communications Register. Figure 5 shows a
flowchart for reading from the different registers on the part summarizing the sequence and the words to be written to access each of
the registers. Figure 6 gives a flowchart for writing to the different registers on the part, again summarizing the sequence and words
to be written to the AD7730.
Figure 5. Flowchart for Reading from the AD7730 Registers
Figure 6. Flowchart for Writing to the AD7730 Registers
Register Byte Y (Hex)
Communications Register 00
Data Register Read Only Register
Mode Register 02
Filter Register 03
DAC Register 04
Offset Register 05
Gain Register 06
Test Register User is advised not to change
contents of Test Register.
Byte W Byte Y Byte Z
Register (Hex) (Hex) (Hex)
Status Register 10 20 30
Data Register 11 21 30
Mode Register 12 22 30
Filter Register 13 N/A* N/A*
DAC Register 14 N/A* N/A*
Offset Register 15 N/A* N/A*
Gain Register 16 N/A* N/A*
Test Register 17 N/A* N/A*
*N/A= Not Applicable. Continuous reads of these registers does not make sense
as the register contents would remain the same since they are only changed by a
write operation.
START
WRITE BYTE W TO
COMMUNICATIONS REGISTER
(SEE ACCOMPANYING TABLE)
YES
READ REGISTER
NO
WRITE BYTE Y TO
COMMUNICATIONS REGISTER
(SEE ACCOMPANYING TABLE)
READ REGISTER
YES
NO
WRITE
BYTE Z TO
COMMUNICATIONS REGISTER
(SEE ACCOMPANYING TABLE)
STOP
CONTINUOUS
READ
OPERATION?
CONTINUOUS
READS OF
REGISTER
REQUIRED?
START
WRITE BYTE Y TO
COMMUNICATIONS REGISTER
(SEE ACCOMPANYING TABLE)
WRITE TO REGISTER
END
REV. B