ASD1194 datasheet(35/76 Pages) TI

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ADS1194, ADS1196

ADS1198

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SBAS471C

– APRIL 2010 – REVISED NOVEMBER 2011

SPI COMMAND DEFINITIONS

The ADS1194/6/8 provide flexible configuration control. The opcode commands, summarized in Table 9, control

and configure the operation of the ADS1194/6/8. 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 ADS1194/6/8 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 9. Command Definitions

COMMAND

DESCRIPTION

FIRST BYTE

SECOND BYTE

System Commands

WAKEUP

Wake-up from standby mode. NOP command in normal 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)

RREG

Read n nnnn registers starting at address rrrr

001r rrrr (2xh)(2)

000n nnnn (2)

WREG

Write n nnnn registers starting at address 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 nnnn = 0 (0010). rrrr = starting

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 following command must be sent after 4 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.

RESET: Reset Registers to Default Values

This command resets the digital filter cycle and returns all register settings to the 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. It takes 18 CLK cycles to execute the RESET command.

Avoid sending any commands during this time.

START: Start Conversions

This opcode starts data conversions. Tie the START pin low to control conversions by command. If conversions

are in progress this command has no effect. The STOP opcode command is used to stop conversions. If the

START command is immediately followed by a STOP command then have a gap of 4 CLK cycles between them.

When the START opcode is sent to the device, keep the START pin low until the STOP command is issued.

(See the START 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.

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Product Folder Link(s): ADS1194 ADS1196 ADS1198

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