Datasheet

ADS1294, ADS1294R
ADS1296, ADS1296R
ADS1298, ADS1298R
SBAS459I –JANUARY 2010–REVISED JANUARY 2012 www.ti.com
SPI COMMAND DEFINITIONS
The ADS129x provide flexible configuration control. The opcode commands, summarized in Table 11, control
and configure the operation of the ADS129x. The opcode commands are stand-alone, except for the register
read and register write operations that require a second command byte plus data. CS can be taken high or held
low between opcode commands but must stay low for the entire command operation (especially for multi-byte
commands). System opcode commands and the RDATA command are decoded by the ADS129x on the seventh
falling edge of SCLK. The register read/write opcodes are decoded on the eighth SCLK falling edge. Be sure to
follow SPI timing requirements when pulling CS high after issuing a command.
Table 11. Opcode Command Definitions
COMMAND DESCRIPTION FIRST BYTE SECOND BYTE
System Commands
WAKEUP Wake-up from standby mode 0000 0010 (02h)
STANDBY Enter standby mode 0000 0100 (04h)
RESET Reset the device 0000 0110 (06h)
START Start/restart (synchronize) conversions 0000 1000 (08h)
STOP Stop conversion 0000 1010 (0Ah)
Data Read Commands
Enable Read Data Continuous mode.
RDATAC 0001 0000 (10h)
This mode is the default mode at power-up.
(1)
SDATAC Stop Read Data Continuously mode 0001 0001 (11h)
RDATA Read data by command; supports multiple read back. 0001 0010 (12h)
Register Read Commands
RREG Read n nnnn registers starting at address r rrrr 001r rrrr (2xh)
(2)
000n nnnn
(2)
WREG Write n nnnn registers starting at address r rrrr 010r rrrr (4xh)
(2)
000n nnnn
(2)
(1) When in RDATAC mode, the RREG command is ignored.
(2) n nnnn = number of registers to be read/written – 1. For example, to read/write three registers, set n nnnn = 0 (0010). r rrrr = starting
register address for read/write opcodes.
WAKEUP: Exit STANDBY Mode
This opcode exits the low-power standby mode; see the STANDBY: Enter STANDBY Mode subsection of the
SPI Command Definitions section. Time is required when exiting standby mode (see the Electrical
Characteristics for details). There are no restrictions on the SCLK rate for this command and it can be
issued any time. Any subsequent command must be sent after 4 t
CLK
cycles.
STANDBY: Enter STANDBY Mode
This opcode command enters the low-power standby mode. All parts of the circuit are shut down except for the
reference section. The standby mode power consumption is specified in the Electrical Characteristics. There are
no restrictions on the SCLK rate for this command and it can be issued any time. Send a WAKEUP
command to return device to normal operation. Serial interface is active, thus register read/write commands are
permitted while in this mode.
RESET: Reset Registers to Default Values
This command resets the digital filter cycle and returns all register settings to the respective default values. See
the Reset (RESET) subsection of the SPI Interface section for more details. There are no restrictions on the
SCLK rate for this command and it can be issued any time. 18 t
CLK
cycles are required to execute the
RESET command. Avoid sending any commands during this time.
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