AD7714
the data register has taken place, the second where the DRDY
bit of the Communications Register is interrogated to see if a
data register update has taken place. Also included in the flow-
ing diagram is a series of words which should be written to the
registers for a particular set of operating conditions. These con-
ditions are test channel (AIN6/AIN6), gain of 1, burnout cur-
rent off, no filter sync, bipolar mode, 24-bit word length, boost
off and maximum filter word (4000 decimal).
CONFIGURING THE AD7714
The AD7714 contains eight on-chip registers that can be
accessed via the serial interface. Communication with any of
these registers is initiated by writing to the Communications
Register first. Figure 8 outlines a flow diagram of the sequence
which is used to configure all registers after a power-up or reset.
The flowchart also shows two different read options—the first
where the DRDY pin is polled to determine when an update of
START
POWER-ON/RESET FOR AD7714
CONFIGURE & INITIALIZE µC/µP SERIAL PORT
WRITE TO COMMUNICATIONS REGISTER SETTING UP
CHANNEL & SETTING UP NEXT OPERATION TO BE A
WRITE TO THE FILTER HIGH REGISTER (27 HEX)
WRITE TO FILTER HIGH REGISTER SETTING
UP REQUIRED VALUES (4F HEX)
WRITE TO COMMUNICATIONS REGISTER SETTING UP
SAME CHANNEL & SETTING UP NEXT OPERATION TO
BE A WRITE TO THE FILTER LOW REGISTER (37 HEX)
WRITE TO FILTER LOW REGISTER SETTING
UP REQUIRED VALUES (A0 HEX)
WRITE TO COMMUNICATIONS REGISTER SETTING UP
SAME CHANNEL & SETTING UP NEXT OPERATION TO
BE A WRITE TO THE MODE REGISTER (17 HEX)
WRITE TO MODE REGISTER SETTING UP REQUIRED
VALUES & INITIATING A CALIBRATION (20 HEX)
POLL DRDY PIN
POLL DRDY BIT OF COMMUNICATIONS REGISTER
NO
DRDY
LOW?
WRITE TO COMMUNICATIONS REGISTER SETTING UP
SAME CHANNEL & SETTING UP NEXT OPERATION TO BE A
READ FROM THE COMMUNICATIONS REGISTER (0F HEX)
YES
WRITE TO COMMUNICATIONS REGISTER SETTING UP
SAME CHANNEL & SETTING UP NEXT OPERATION TO
BE A READ FROM THE DATA REGISTER (5F HEX)
READ FROM COMMUNICATIONS REGISTER
READ FROM DATA REGISTER
NO
DRDY
LOW?
YES
WRITE TO COMMUNICATIONS REGISTER SETTING UP
SAME CHANNEL & SETTING UP NEXT OPERATION TO
BE A READ FROM THE DATA REGISTER (5F HEX)
READ FROM DATA REGISTER
Figure 8. Flowchart for Setting Up and Reading from the AD7714
–30–
REV. C
ADI [ ADI ]
