Texas Instruments ADS869 Series Manual page 43

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8.4.2.5 Auto Channel Enable with Reset (AUTO_RST)
The devices can be programmed to scan the input signal on all analog channels automatically by writing a valid
auto channel sequence with a reset (AUTO_RST, A000h) command in the command register, as explained in
Figure 84. As shown in Figure
or after reading the output data of the frame. However, in order to accurately acquire and convert the input signal
on the first selected channel in the next data frame, the command frame must be a complete frame of 34 SCLK
cycles.
The sequence of channels for the automatic scan can be configured by the AUTO SCAN sequencing control
register (01h to 02h) in the program register; see the
continuously cycle through the selected channels in ascending order, beginning with the lowest channel and
converting all channels selected in the program register. On completion of the sequence, the devices return to
the lowest count channel in the program register and repeat the sequence. The input voltage range for each
channel in the auto-scan sequence can be configured by setting the
registers.
Sample N
CS
1 2 14
SCLK
SDI AUTO_RST Command ± A000h
SDO
The devices remain in AUTO_RST mode if no other valid command is executed and SDI is kept low (see the
Continued Operation in the Selected Mode (NO_OP)
command is executed again at any time during this mode of operation, then the sequence of the scanned
channels is reset. The devices return to the lowest count channel of the auto-scan sequence in the program
register and repeat the sequence. The timing diagram in
which channels 0 to 2 are selected in the auto sequence. For switching between AUTO_RST mode and
MAN_Ch_n mode; see the
Sample
N
CS
SCLK
SDI
AUTO_RST xxxx
SDO
Sample N Data
Based on Previous
Mode Setting
Copyright © 2015, Texas Instruments Incorporated
84, the CS signal can be pulled high immediately after the AUTO_RST command
CS can go high immediately after AUTO_RST
command or after reading frame data.
15 16 17 18 32 33
X
X X X
Data from Sample N
D17 D16 D3 D2
Figure 84. Enter AUTO_RST Mode Timing Diagram
Channel Sequencing Modes
Ch 0 Ch 1
Sample Sample
0000h xxxx
Ch 0 Data
AUTO_RST Mode
(Channels 0-2 are selected in sequence.)
Figure 85. Device Operation Example in AUTO_RST Mode
Product Folder Links:
Program Register Map
Range Select Registers
Enters AUTO_RST Mode on CS Rising Edge
st
Samples 1 Ch. of Auto-Ch Sequence
34 1 2
X X X X
D1 D0
section) during subsequent data frames. If the AUTO_RST
Figure 85 shows this behavior using an example in
section.
Ch 2
Sample
0000h xxxx AUTO_RST
Ch 1 Data
ADS8694 ADS8698
ADS8694, ADS8698
SBAS686 – JULY 2015
section. In this mode, the devices
of the program
Samples 2
Auto-Ch Sequence
14 15 16 34
33
Stays in AUTO_RST Mode if
SDI is Low in a Data Frame
st
Data from 1 Ch of Seq.
Ch 0
Sample
xxxx 0000h
Ch 2 Data
AUTO_RST Mode
(Channel sequence restarted from
lowest count.)
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nd
Ch. of
xxxx
Ch 0 Data
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