Datasheet

Data Sheet AD7327
Rev. B | Page 25 of 36
SEQUENCER OPERATION
DIN: WRITE TO RANGE REGISTER 1 TO SELECT THE RANG
E
F
O
R E
ACH ANA
L
OG IN
PU
T CHANNEL.
DOUT: CONVERSION RESULT FROM CHANNEL 0, ±10V
RANGE,
SI
N
GL
E-END
E
D M
OD
E.
CS
DIN:
TIE DIN LO
W/W
RIT
E BIT = 0 TO CONTINUE TO CONVERT
THROUGH
THE SE
QUENCE OF CHANNELS.
DO
UT: CONVERSION RESULT FROM FIRST CHANNEL IN
THE SEQUENCE.
C
S
DIN: WRI
TE TO
SEQU
ENCE
REGISTER TO SE
LECT THE
NEW
SEQU
ENCE.
DO
UT:
CON
VERSION RESULT F
ROM
CHANNEL X IN
T
HE FIRST SEQUENCE.
C
S
DIN: WRITE TO RANGE
RE
GIS
T
ER 2 TO SELECT THE RANGE
FOR EACH
ANAL
OG IN
P
UT
CHANN
EL
.
DO
UT
:
CO
NVERSION RESULT FROM CHANNE
L 0
,
S
I
NG
LE-E
ND
ED
MO
D
E,
RANG
E
SELECTED IN
RAN
GE REGISTER 1.
CS
DI
N: WR
I
TE TO
CON
TRO
L RE
GISTE
R TO START THE
SEQUENCE, Seq1 = 0, Seq2 = 1.
DO
UT:
CONVE
RSION RESULT FROM CHANNEL 0,
SI
NGL
E-ENDE
D MODE, RANGE SELECTED IN
RANGE REGISTER 1.
CS
DIN: WRI
T
E T
O SE
Q
UE
NCE
R
EGI
ST
E
R T
O
SEL
EC
T
TH
E
ANALOG INPUT CHANN
EL
S
TO
B
E I
NCL
UDED IN
TH
E
SEQ
UE
NC
E.
DO
UT:
CON
VERSION RESULT FR
OM CHANN
EL 0
,
S
ING
LE-END
ED MODE, RANGE SE
LEC
TED
IN
RANGE REGISTER 1.
CS
POWER ON.
CONTINUOUSLY CON
VERT
ON THE SELECTED SEQUENC
E
OF CHANNELS.
DIN TIED LOW/WRITE BIT = 0.
SELECTI
NG A N
EW SE
QUENCE.
DIN: WRITE TO CONTROL
REGISTER TO STOP THE
SEQUENCE, Seq1 = 0, Seq2 = 0.
D
OUT: CONVERSION RESULT
F
ROM
CHANNEL IN SEQUENCE.
CS
STOPPING
A SEQUENCE.
05401-031
Figure 44. Programmable Sequence Flowchart
The AD7327 can be configured to automatically cycle through a
number of selected channels using the on-chip sequence register
with the Seq1 bit and the Seq2 bit in the control register. Figure 44
shows how to program the AD7327 register to operate in
sequence mode.
After power-up, all of the four on-chip registers contain default
values. Each analog input has a default input range of ±10 V. If
different analog input ranges are required, a write to the range
registers is required. This is shown in the first two serial transfers
of Figure 44.
These two initial serial transfers are only necessary if input
ranges other than the default ranges are required. After the
analog input ranges are configured, a write to the sequence
register is necessary to select the channels to be included in the
sequence. Once the channels for the sequence have been selected,
the sequence can be initiated by writing to the control register
and setting Seq1 to 0 and Seq2 to 1. The AD7327 continues to
convert through the selected sequence without interruption,
provided the sequence register remains unchanged and Seq1 =
0 and Seq2 = 1 in the control register.