Datasheet

Data Sheet AD7328
Rev. C | Page 25 of 36
SEQUENCER OPERATION
DIN: WRITE TO RANGE REGISTER 1 TO SELECT THE RANGE
FOR EACH ANALOG INPUT CHANNEL.
DOUT: CONVERSION RESULT FROM CHANNEL 0, ± 10V
RANGE, SINGLE-ENDED MODE.
CS
DIN: TIE DIN LOW/WRITE BIT = 0 TO CONTINUE TO CONVERT
THROUGH THE SEQUENCE OF CHANNELS.
DOUT: CONVERSION RESULT FROM FIRST CHANNEL IN
THE SEQUENCE.
CS
DIN: WRITE TO SEQUENCE REGISTER TO SELECT THE
NEW SEQUENCE.
DOUT: CONVERSION RESULT FROM CHANNEL X IN
THE FIRST SEQUENCE.
CS
DIN: WRITE TO RANGE REGISTER 2 TO SELECT THE RANGE
FOR EACH ANALOG INPUT CHANNEL.
DOUT: CONVERSION RESULT FROM CHANNEL 0,
SINGLE-ENDED MODE, RANGE SELECTED IN
RANGE REGISTER 1.
CS
DIN: WRITE TO CONTROL REGISTER TO START THE
SEQUENCE, SEQ1 = 0, SEQ2 = 1.
DOUT: CONVERSION RESULT FROM CHANNEL 0,
SINGLE-ENDED MODE, RANGE SELECTED IN
RANGE REGISTER 1.
CS
DIN: WRITE TO SEQUENCE REGISTER TO SELECT THE
ANALOG INPUT CHANNELS TO BE INCLUDED IN
THE SEQUENCE.
DOUT: CONVERSION RESULT FROM CHANNEL 0,
SINGLE-ENDED MODE, RANGE SELECTED IN
RANGE REGISTER 1.
CS
POWER ON.
CONTINUOUSLY CONVERT
ON THE SELECTED SEQUENCE
OF CHANNELS.
DIN TIED LOW/WRITE BIT = 0.
SELECTING A NEW SEQUENCE.
DIN: WRITE TO CONTROL
REGISTER TO STOP THE
SEQUENCE, SEQ1 = 0, SEQ2 = 0.
DOUT: CONVERSION RESULT
FROM CHANNEL IN SEQUENCE.
CS
STOPPING
A SEQUENCE.
04852-031
Figure 44. Programmable Sequence Flowchart
The AD7328 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 AD7328 register to operate in
sequence mode.
After power-up, all 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
necessary. This is shown in the first two serial transfers of Figure 44.
These two initial serial transfers are required only 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. After 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 AD7328 continues to convert the selected
sequence without interruption if the sequence register remains
unchanged and SEQ1 = 0 and SEQ2 = 1 in the control register.