Datasheet

Data Sheet AD7329
Rev. B | Page 29 of 40
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.
SELECT A NEW SEQUENCE.
DIN: WRITE TO CONTROL
REGISTER TO STOP THE
SEQUENCE, SEQ1 = 0, SEQ2 = 0.
DOUT: CONVERSION RESULT
FROM CHANNEL IN SEQUENCE.
CS
STOP
A SEQUENCE.
05402-044
Figure 48. Programmable Sequence Flowchart
The AD7329 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 48 shows how to program the AD7329 register
to operate in sequence mode.
After power-up, 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 necessary. This is shown in the first two serial
transfers of Figure 48.
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 AD7329 continues to convert the selected
sequence without interruption if the sequence register remains
unchanged and SEQ1 = 0 and SEQ2 = 1 in the control register.