COMBOSMARTMETER datasheet(34/60 Pages) TI1

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START

DRDY

SCLK

DIN

DOUT

Hi-Z

RDATAC Opcode

Status Register + n-Channel Data

Next Data

t UPDATE

(1)

ADS131E04

ADS131E06

ADS131E08

SBAS561A – JUNE 2012 – REVISED APRIL 2013

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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 tCLK 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 SCLK rate restrictions

for this command and it can be issued at any time.

STOP: Stop Conversions

This opcode stops conversions. Tie the START pin low to control conversions by command. When the STOP

command is sent, the conversion in progress completes and further conversions are stopped. If conversions are

already stopped, this command has no effect. There are no SCLK rate restrictions for this command and it

can be issued at any time.

OFFSETCAL: Channel Offset Calibration

This command is used to cancel the channel offset. OFFSETCAL must be executed every time there is a change

in PGA gain settings.

RDATAC: Read Data Continuous

This opcode enables the conversion data output on each DRDY without the need to issue subsequent read data

opcodes. This mode places the conversion data in the output register and may be shifted out directly. The read

data continuous mode is the default mode of the device and the device defaults in this mode on power-up.

RDATAC mode is cancelled by the Stop Read Data Continuous command. If the device is in RDATAC mode, an

SDATAC command must be issued before any other commands can be sent to the device. There are no SCLK

rate restrictions for this command. However, subsequent data retrieval SCLKs or the SDATAC opcode

command should wait at least 4 tCLK cycles for the command to execute. RDATAC timing is shown in Figure 39.

As Figure 39 shows, there is a keep out zone of 4 tCLK cycles around the DRDY pulse where this command

cannot be issued in. If no data are retrieved from the device, DOUT and DRDY behave similarly in this mode. To

retrieve data from the device after the RDATAC command is issued, make sure either the START pin is high or

the START command is issued. Figure 39 shows the recommended way to use the RDATAC command.

RDATAC is ideally-suited for applications such as data loggers or recorders where registers are set once and do

not need to be reconfigured.

(1) tUPDATE = 4 / fCLK. Do not read data during this time.

Figure 39. RDATAC Usage

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Product Folder Links: ADS131E04 ADS131E06 ADS131E08

COMBOSMARTMETER Datasheet(PDF) 34 Page - Texas Instruments

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