Datasheet

AD7323 Data Sheet
Rev. B | Page 26 of 36
SEQUENCER OPERATION
The AD7323 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 AD7323 register to
operate in sequence mode.
After power-up, all of the three 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
register is required. This is shown in the first serial transfer of
Figure 44.
This initial serial transfer is 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.
When the channels for the sequence have been selected, the
sequence can be initiated by writing to the control register and
setting Seq1 = 0 and Seq2 = 1. The AD7323 continues to
convert the selected sequence without interruption provided
that the sequence register remains unchanged, and Seq1 = 0 and
Seq2 = 1 in the control register.
DIN: WRITE TO RANGE REGISTER 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 CONTROL REGISTER TO START THE
SEQUENCE, Seq1 = 0, Seq2 = 1.
DOUT: CONVERSION RESULT FROM CHANNEL 0,
SINGLE-ENDED MODE, RANGE SELECTED IN
RANGE REGISTER.
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.
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.
05400-031
Figure 44. Programmable Sequence Flowchart