ADS8694 Datasheet, PDF (48/77 Pages) Texas Instruments – 4- and 8-Channel, Single-Supply, SAR ADCs

ADS8694, ADS8698
SBAS686 – JULY 2015
www.ti.com
8.5.2 Program Register Description
The program register is a 16-bit register used to set the operating modes of the ADS8694 and ADS8698. The
settings in this register are used to select the channel sequence for AUTO_RST mode, configure the device ID in
daisy-chain mode, select the SDO output format, control input range settings for individual channels, control the
ALARM feature, reading the alarm flags, and programming the alarm thresholds for each channel. All program
settings for this register are listed in Table 9. During power-up or reset, the different program registers in the
device wake up with their default values and the device waits for a command to be written before being placed
into any mode of operation.
8.5.2.1 Program Register Read/Write Operation
The program register is a 16-bit read or write register. There must be a minimum of 24 SCLKs after the CS
falling edge for any read or write operation to the program registers. When CS goes low, the SDO line goes low
as well. The device receives the command (see Table 7 and Table 8) through SDI where the first seven bits (bits
15-9) represent the register address and the eighth bit (bit 8) is the write or read instruction.
For a write cycle, the next eight bits (bits 7-0) on SDI are the desired data for the addressed register. Over the
next eight SCLK cycles, the device outputs this 8-bit data that is written into the register. This data readback
allows verification to determine if the correct data are entered into the device. A typical timing diagram for a
program register write cycle is shown in Figure 91.
Table 7. Write Cycle Command Word
PIN
REGISTER ADDRESS
(Bits 15-9)
WR/RD
(Bit 8)
DATA
(Bits 7-0)
SDI
ADDR[6:0]
1
DIN[7:0]
Sample
N
CS
SCLK
1
2
6
7
8
9
10
15 16 17 18
23 24
SDI
ADDR [6:0]
WR
DIN [7:0]
XXXX
SDO
Data written into register, DIN [7:0]
Figure 91. Program Register Write Cycle Timing Diagram
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